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This is the Discovery Files
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podcast from the U.S.
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National Science Foundation.
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Materials research has yielded
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countless breakthroughs,
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from silicon semiconductors
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to the hydrogels used in
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contact lenses and wound dressings.
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NSF investments are advancing
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the golden age of American innovation
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through the development of critical
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and emerging technologies,
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including artificial intelligence,
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biotechnologies, and quantum
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information science.
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We're joined today by Morteza Kayyalha,
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an NSF-supported researcher
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whose Quantum Devices Lab
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focuses on electrical, thermoelectric,
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and superconducting properties
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of quantum materials.
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Professor Kayyalha
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thank you so much for joining me today.
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Thanks for having me.
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I appreciate it.
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We're going
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to get into some dense stuff here.
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So I want to start with
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kind of a definition for a public
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that is only hearing the term
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and doesn't really have a grasp of it,
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can you broadly define quantum?
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So quantum is
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basically the laws that we use
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to describe nature
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at the small scale.
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Things when they
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when they become small,
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they behave kind of like
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weirdly,
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that is not very intuitive to us,
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like human beings.
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For example, you can have what we call
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a superposition.
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And the best example I have
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that kind of like describe
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superposition is when you toss a coin,
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you expect to get heads or tails.
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But imagine you toss a coin
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and it just starts spinning.
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So it's neither tails
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or heads.
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So that's kind of
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like a quantum state, quantum system
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in a superposition state.
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We can have entanglements
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and coherence / decoherence.
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But in general quantum
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is how we describe things
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at a small scale.
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And then I want also noted a distinction
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that has become very important
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these days is
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like we used to have
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quantum mechanics.
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So that's I would call
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the first quantum revolution,
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like back in the day
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when transistors were invented.
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And that's the computer age.
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We have computers,
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we have cell phones and everything,
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every devices that we have
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in those tools,
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they use quantum mechanics.
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But nowadays
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when we use the word quantum,
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we are kind of like referring to
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something is slightly different.
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And that's I would
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use the term quantum information
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science or quantum computing.
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And they're what we are referring to
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is like a new generation of computers
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and new ways of communication
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that relies mostly
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on fundamental quantum properties
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like superposition, like entanglement,
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things that we didn't
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necessarily leverage
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when we were making,
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like the laptops that we have
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or this camera that I'm speaking to.
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So that's a distinction that I think
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a general public
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would appreciate being aware of.
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Very much cutting edge
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of where technology is right now.
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That's correct, yes.
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So thinking about that technology,
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I would like to ask you
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how you're working with quantum devices
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and quantum materials in your lab.
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In my lab we use materials,
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and then we either
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develop them ourselves in the lab,
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or we collaborate
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with materials scientists
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who kind of, like,
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create these new materials.
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And then we make new devices out of them.
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And the goal of the devices
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is just to study
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some of these quantum properties.
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So the materials and devices
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that we are interested in
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and we are exploring
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are those that,
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in some way or another,
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have some potential
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to exhibit properties
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that are kind of like new
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or unexpected
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when it comes to quantum scale.
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And then we mostly study
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the fundamental properties in the lab,
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but then we have our eyes
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set in some of the applications
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that these fundamental properties
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might enable in the future.
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Like, for example, can
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we develop a new material
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and make a new device
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that might lead to
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a quantum computer
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that is not noisy
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or can help
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scale up the quantum system?
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So we have
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those general goals in mind.
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But in the lab, we overall
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work with materials and devices.
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It's the intersection between
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material science,
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device physic,
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electrical engineering
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and quantum physics.
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So we have like
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a very nice
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interdisciplinary research
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going on in the lab.
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Moving into the work
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that brought you to my attention today.
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You have a recently published paper,
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and there's a couple specific areas of it
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that are important to explaining
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what you're doing that
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I think we need to examine a little bit.
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And I want to ask you, what are non
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Hermitian physics?
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Non-Hermitian physics like generally
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when we talk about quantum, quantum
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systems,
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we have this rule.
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We call it like a closed box.
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So imagine a system
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that is isolated from
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its environment is just
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sitting there in isolation.
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And then the study is property.
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That's the gist of a Hermitian system.
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But in reality
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what happens is
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the system is never fully isolated.
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It communicates with its environment,
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is in interaction
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with the with the environment.
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And as a result of this interaction
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or these interactions,
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it gains energy or loses some energy.
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So there are like gain and losses
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that are involved
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because of these interactions
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that the system has with the environment.
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And as a result of that,
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you get these things that we call
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non Hermitian physics.
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And why they're interesting
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is non Hermitian systems
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can have their own kind
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of like uniqueness.
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They can lead to a properties
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that you would otherwise
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not observe
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in a Hermitian system, in a system
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that is completely closed.
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For example,
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one is what
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we actually studied in this paper
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called the non Hermitian skin effect.
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And what that means is that for example,
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in our case,
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electrical current
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is getting localized
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in one end of a chain
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instead of being
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uniformly distributed across the chain.
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Or you can
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you can have this localization emerging
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variety of different ways.
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That's why we call it a skin effects.
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Like in a wire,
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if a current is only on
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the surface of the wire,
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you have a skin effect.
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So it's like the current
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is not inside
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the wire is only on the surface.
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So it's kind of like this
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localization property.
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And this can have its own application
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whenever you want to do sensing later on.
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So, part of the interest in my lab
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with a non Hermitian
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physics is what kind of new
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properties can be discovered.
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And then the next question is
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how can we connect them
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to applications.
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So moving into the applications
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I guess or the device
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quantum anomalous Hall insulators
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is the next one I want to ask you about.
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What are they and
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how might they be advantageous.
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Quantum anomalous Hall insulators.
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The name anomalous
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is basically telling
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us that it's a quantum
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Hall insulator, but it's anomalous.
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But I understand that for somebody
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listening to this
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quantum Hall
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might also be as strange of a name.
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So maybe the best way
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I can explain
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this is typically
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the materials that we work with
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are in three dimensions,
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like everything is big,
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but then imagine you
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scale the thickness down to
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feel nanometers, tens of nanometers.
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So those in that scale range,
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we get to systems
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that we can kind of like
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call them two dimensional.
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So the thickness is no longer
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very important.
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It's mostly
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the trans or the electrical current.
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Electricity is carried
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along the 2D
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surface of the system.
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So in those type of materials,
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if you thin them down
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we call them two dimensional
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materials basically,
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or two dimensional electron systems.
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In those systems if you apply
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very strong magnetic field,
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what happens is
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you get this quantum Hall insulator.
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And what that means
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is simply
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electricity is only going
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around the perimeter of the material,
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and the bulk
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is not carrying
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electricity.
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So quantum anomalous Hall
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insulator is a material
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that has electricity
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moving along its perimeter.
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The bulk has no electrical current
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and this happens
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without the magnetic field,
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thus the name anomalous.
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So quantum hall you need magnetic field.
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Quantum anomalous Hall.
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No magnetic field is needed.
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And that's great
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because not having magnetic
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field removes
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one of the limitation
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of using these materials
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for certain applications.
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00:08:53,065 --> 00:08:54,667
So mixing these things together,
299
00:08:54,700 --> 00:08:56,235
can we talk about the device
300
00:08:56,235 --> 00:08:58,137
that you've put together in this paper.
301
00:08:58,170 --> 00:08:58,538
Sure.
302
00:08:58,538 --> 00:09:01,073
So what we decided to do was
303
00:09:01,107 --> 00:09:02,575
look at these quantum
304
00:09:02,575 --> 00:09:04,110
anomalous insulators
305
00:09:04,110 --> 00:09:05,578
and then see whether
306
00:09:05,578 --> 00:09:07,346
they can build
307
00:09:07,346 --> 00:09:09,115
anything or create
308
00:09:09,115 --> 00:09:11,717
any non Hermitian properties in them.
309
00:09:11,717 --> 00:09:14,186
And the best way I can explain
310
00:09:14,186 --> 00:09:17,156
this is we created sites
311
00:09:17,189 --> 00:09:18,891
across this quantum
312
00:09:18,891 --> 00:09:20,226
anomalous insulators.
313
00:09:20,226 --> 00:09:22,695
And then we leverage this property
314
00:09:22,695 --> 00:09:25,398
that between the sites electricity
315
00:09:25,431 --> 00:09:27,867
only flows in one direction.
316
00:09:27,867 --> 00:09:31,237
So if I have imagine this size of cities,
317
00:09:31,270 --> 00:09:32,638
if I have two cities,
318
00:09:32,705 --> 00:09:33,873
there is a one way road
319
00:09:33,873 --> 00:09:34,874
connecting the city.
320
00:09:34,874 --> 00:09:37,443
So cars can go from City 1 to City two,
321
00:09:37,443 --> 00:09:38,744
but they cannot come back.
322
00:09:38,744 --> 00:09:40,479
And then what we showed
323
00:09:40,513 --> 00:09:42,014
was using
324
00:09:42,014 --> 00:09:43,516
this unique property
325
00:09:43,516 --> 00:09:44,717
that quantum and almost
326
00:09:44,717 --> 00:09:46,419
all insulated it provides for us.
327
00:09:46,452 --> 00:09:47,720
We can make
328
00:09:47,753 --> 00:09:50,356
or we can observe the non
329
00:09:50,356 --> 00:09:51,557
Hermitian skin effect
330
00:09:51,557 --> 00:09:52,692
that I was telling you about.
331
00:09:52,692 --> 00:09:54,260
So regardless of where
332
00:09:54,260 --> 00:09:55,461
I inject
333
00:09:55,494 --> 00:09:57,897
electricity in this device
334
00:09:57,930 --> 00:10:00,132
or in our example to
335
00:10:00,199 --> 00:10:01,534
if I want to use that example,
336
00:10:01,867 --> 00:10:03,903
regardless of where the cars are coming
337
00:10:04,303 --> 00:10:05,905
to the cities,
338
00:10:06,138 --> 00:10:07,306
whether they come to City
339
00:10:07,306 --> 00:10:08,574
A, City B, City
340
00:10:08,574 --> 00:10:09,976
C, so on and so forth.
341
00:10:10,042 --> 00:10:11,911
They all go and eventually
342
00:10:11,911 --> 00:10:13,112
end up
343
00:10:13,145 --> 00:10:14,547
the last city that we have.
344
00:10:14,580 --> 00:10:15,781
So it doesn't matter
345
00:10:15,781 --> 00:10:17,083
where
346
00:10:17,083 --> 00:10:18,417
at what point they enter
347
00:10:18,417 --> 00:10:19,785
the device.
348
00:10:19,819 --> 00:10:22,388
The electricity will always
349
00:10:22,388 --> 00:10:23,623
localize towards
350
00:10:23,623 --> 00:10:25,491
the end of the chain.
351
00:10:25,591 --> 00:10:27,093
And that's what we did.
352
00:10:27,093 --> 00:10:28,995
So we showed that
353
00:10:29,061 --> 00:10:30,363
in this quantum anomalous hall insulator
354
00:10:30,930 --> 00:10:32,732
we can observe this
355
00:10:32,798 --> 00:10:35,401
fundamental property that we call
356
00:10:35,534 --> 00:10:36,636
skin effect.
357
00:10:36,636 --> 00:10:38,070
So why would you want
358
00:10:38,070 --> 00:10:39,338
to bring this into
359
00:10:39,372 --> 00:10:40,506
say a competing system,
360
00:10:40,506 --> 00:10:42,975
why would this be useful in a computer?
361
00:10:43,042 --> 00:10:44,477
Oh that's a very good question.
362
00:10:44,477 --> 00:10:47,079
So there are people theorists
363
00:10:47,079 --> 00:10:48,547
who know more about these things,
364
00:10:48,547 --> 00:10:51,117
and they have predicted that
365
00:10:51,117 --> 00:10:53,252
if we create such a device
366
00:10:53,252 --> 00:10:56,155
that we have built in our lab, then
367
00:10:56,322 --> 00:10:58,491
depending on the number of sites
368
00:10:58,491 --> 00:10:59,992
that we have in the chains
369
00:11:00,026 --> 00:11:01,794
in this example, in my example,
370
00:11:01,794 --> 00:11:03,596
it would be number of cities.
371
00:11:03,896 --> 00:11:06,298
You get certain sensitivity
372
00:11:06,332 --> 00:11:07,900
if you perturb the system.
373
00:11:07,933 --> 00:11:09,835
Let's say you have a tiny electric field,
374
00:11:09,869 --> 00:11:10,936
tiny magnetic field
375
00:11:10,936 --> 00:11:12,438
that perturbs your system.
376
00:11:12,438 --> 00:11:15,141
And you want to measure the amplitude
377
00:11:15,141 --> 00:11:16,642
of that perturbation.
378
00:11:17,376 --> 00:11:19,078
The theoretical prediction is
379
00:11:19,078 --> 00:11:21,280
if you have ten cities in your device
380
00:11:21,280 --> 00:11:23,215
or ten sites in your device,
381
00:11:23,215 --> 00:11:25,251
you get certain amplification
382
00:11:25,251 --> 00:11:26,652
of that perturbation.
383
00:11:26,652 --> 00:11:28,320
But if you have 100,
384
00:11:28,354 --> 00:11:30,356
you get exponentially more
385
00:11:30,423 --> 00:11:31,624
amplification.
386
00:11:31,624 --> 00:11:33,459
So you can imagine doing
387
00:11:33,459 --> 00:11:36,228
sensing with this device.
388
00:11:36,395 --> 00:11:39,098
And the way your sensor would work is
389
00:11:39,098 --> 00:11:40,866
you can show by increasing
390
00:11:40,866 --> 00:11:42,468
the number of chains
391
00:11:42,468 --> 00:11:44,737
or the number of sites, number of cities.
392
00:11:44,737 --> 00:11:45,938
In my example,
393
00:11:46,272 --> 00:11:48,107
you have enhanced
394
00:11:48,107 --> 00:11:49,041
exponentially
395
00:11:49,041 --> 00:11:50,876
the sensitivity of your sensor.
396
00:11:50,876 --> 00:11:53,012
So this is quite extraordinary
397
00:11:53,012 --> 00:11:54,780
if it turns out to be true.
398
00:11:54,780 --> 00:11:56,148
And one of the advantages
399
00:11:56,148 --> 00:11:58,017
of this quantum and insulator
400
00:11:58,050 --> 00:11:59,251
that we have
401
00:11:59,318 --> 00:12:01,921
is that it is relatively easy to
402
00:12:02,054 --> 00:12:02,822
scale it up.
403
00:12:02,822 --> 00:12:05,391
So making two cities, two sites,
404
00:12:05,458 --> 00:12:07,059
three, four, five
405
00:12:07,259 --> 00:12:08,861
is relatively straightforward
406
00:12:08,861 --> 00:12:10,229
because we use something called
407
00:12:10,229 --> 00:12:11,630
nanofabrication.
408
00:12:11,664 --> 00:12:12,865
This is a technology
409
00:12:12,865 --> 00:12:15,868
we use to make our laptops,
410
00:12:15,868 --> 00:12:17,336
the fabs,
411
00:12:17,703 --> 00:12:19,071
they create these transistors.
412
00:12:19,071 --> 00:12:20,139
So it's very straightforward.
413
00:12:20,139 --> 00:12:22,742
We have all the toolsets available
414
00:12:22,908 --> 00:12:24,844
so that we can easily scale them
415
00:12:24,844 --> 00:12:26,879
on going from ten sites to 20 site
416
00:12:26,912 --> 00:12:29,882
to 100 site to maybe 1000 sites.
417
00:12:29,882 --> 00:12:32,118
And if the amplification,
418
00:12:32,118 --> 00:12:34,019
if this sensitivity enhancement
419
00:12:34,019 --> 00:12:35,755
is turns out to be true,
420
00:12:35,855 --> 00:12:38,257
then you can have very many
421
00:12:38,657 --> 00:12:39,859
signal coming in
422
00:12:39,859 --> 00:12:41,627
and then amplified
423
00:12:41,627 --> 00:12:43,028
by quite a lot
424
00:12:43,028 --> 00:12:44,864
and do sensing of it
425
00:12:44,864 --> 00:12:46,065
basically measure
426
00:12:46,132 --> 00:12:47,933
that small signal.
427
00:12:47,933 --> 00:12:50,669
So that's the whole excitement
428
00:12:50,703 --> 00:12:51,904
that I had.
429
00:12:51,971 --> 00:12:53,572
This is how I got into this,
430
00:12:54,106 --> 00:12:55,374
this field, basically.
431
00:12:55,441 --> 00:12:56,976
You mentioned the nanofabrication,
432
00:12:56,976 --> 00:12:58,010
and I'm thinking about
433
00:12:58,010 --> 00:12:59,345
some of the challenges
434
00:12:59,345 --> 00:13:00,713
working at the quantum scale.
435
00:13:00,746 --> 00:13:01,747
Can you talk a little bit
436
00:13:01,747 --> 00:13:03,349
about the challenges
437
00:13:03,349 --> 00:13:04,550
developing this?
438
00:13:04,717 --> 00:13:06,519
Well, one of the biggest challenges
439
00:13:06,519 --> 00:13:07,720
that we haven't
440
00:13:07,720 --> 00:13:08,954
addressed yet
441
00:13:08,988 --> 00:13:10,189
is with the quantum
442
00:13:10,523 --> 00:13:11,957
anomalous Hall insulator itself.
443
00:13:11,957 --> 00:13:14,293
So these materials,
444
00:13:14,360 --> 00:13:14,794
these
445
00:13:14,794 --> 00:13:16,228
the property that I told you,
446
00:13:16,228 --> 00:13:17,630
the electricity flowing
447
00:13:17,630 --> 00:13:19,665
around the perimeter of the device,
448
00:13:20,065 --> 00:13:22,401
only images at very,
449
00:13:22,401 --> 00:13:23,803
very low temperatures.
450
00:13:23,803 --> 00:13:25,704
So we are getting close
451
00:13:25,704 --> 00:13:27,473
to the absolute zero temperature,
452
00:13:27,506 --> 00:13:28,707
like very, very cold,
453
00:13:28,774 --> 00:13:29,909
colder than anything
454
00:13:29,909 --> 00:13:31,377
that anybody can imagine.
455
00:13:31,377 --> 00:13:33,345
So that's a big challenge
456
00:13:33,345 --> 00:13:34,880
because if you want to have
457
00:13:34,880 --> 00:13:36,148
real applications
458
00:13:36,148 --> 00:13:38,217
that would improve our lives
459
00:13:38,317 --> 00:13:39,585
in a meaningful way,
460
00:13:39,652 --> 00:13:41,453
we want things to be done at room
461
00:13:41,520 --> 00:13:41,954
temperature,
462
00:13:41,954 --> 00:13:43,589
like I'm sitting in this room,
463
00:13:43,589 --> 00:13:45,357
I want my quantum
464
00:13:45,558 --> 00:13:46,292
anomalous Hall insulator
465
00:13:46,292 --> 00:13:47,626
to work at this temperature.
466
00:13:47,626 --> 00:13:50,396
And one of the things that we need
467
00:13:50,396 --> 00:13:52,264
to improve to achieve this goal
468
00:13:52,264 --> 00:13:52,698
is to
469
00:13:52,698 --> 00:13:54,834
improve the quality of the material.
470
00:13:54,834 --> 00:13:57,102
So these materials need to be very pure.
471
00:13:57,136 --> 00:13:58,871
But the challenge is,
472
00:13:59,071 --> 00:14:00,539
at least for us, the quantum
473
00:14:00,539 --> 00:14:01,640
anomalous Hall insulators
474
00:14:01,640 --> 00:14:03,542
that we use are doped.
475
00:14:03,576 --> 00:14:05,711
So they have certain level of impurity.
476
00:14:05,711 --> 00:14:08,280
And this impurity is required
477
00:14:08,714 --> 00:14:09,682
to get the name
478
00:14:09,682 --> 00:14:11,383
anomalous in our quantum
479
00:14:11,383 --> 00:14:12,751
anomalous Hall insulator.
480
00:14:12,785 --> 00:14:14,920
To basically not have any magnetic field
481
00:14:14,954 --> 00:14:16,622
we need to add these impurities.
482
00:14:16,622 --> 00:14:18,057
So the challenge
483
00:14:18,057 --> 00:14:19,491
becomes is a trade off.
484
00:14:19,558 --> 00:14:21,193
I need to add the impurity
485
00:14:21,193 --> 00:14:23,195
so that I don't need the magnetic field.
486
00:14:23,229 --> 00:14:24,864
But the impurity makes
487
00:14:24,864 --> 00:14:26,332
my material not pure.
488
00:14:26,398 --> 00:14:28,801
So that causes the relation
489
00:14:28,801 --> 00:14:30,302
of the material quality.
490
00:14:30,302 --> 00:14:31,704
So I have to kind of like
491
00:14:31,737 --> 00:14:33,539
find the optimal point.
492
00:14:33,539 --> 00:14:34,940
And this is something that
493
00:14:34,974 --> 00:14:36,442
my colleagues at Penn
494
00:14:36,442 --> 00:14:37,676
State are working on
495
00:14:37,710 --> 00:14:40,079
to enhance and improve.
496
00:14:40,112 --> 00:14:42,214
So we can have better,
497
00:14:42,214 --> 00:14:43,782
higher quality materials.
498
00:14:43,782 --> 00:14:44,617
And as a result,
499
00:14:44,617 --> 00:14:46,585
we can have these materials
500
00:14:46,585 --> 00:14:47,987
exhibiting these properties
501
00:14:48,020 --> 00:14:50,422
at closer to room temperatures.
502
00:14:50,422 --> 00:14:52,424
Basically, that would be the the goal.
503
00:14:52,424 --> 00:14:53,592
I would say.
504
00:14:53,592 --> 00:14:56,028
Right, you have to make some compromises
505
00:14:56,028 --> 00:14:57,897
to get the things to work
506
00:14:57,897 --> 00:14:58,797
with, the attributes
507
00:14:58,797 --> 00:15:00,799
you want them to have, and for all of us
508
00:15:00,799 --> 00:15:02,101
to play together nicely.
509
00:15:02,101 --> 00:15:03,235
So you talked a little
510
00:15:03,235 --> 00:15:05,571
bit of the challenges developing there.
511
00:15:05,638 --> 00:15:06,939
What are your next steps
512
00:15:06,939 --> 00:15:08,140
to move this towards
513
00:15:08,140 --> 00:15:10,576
potential commercial applications.
514
00:15:10,643 --> 00:15:11,777
So our next step
515
00:15:11,777 --> 00:15:13,579
is to just make the sensors.
516
00:15:13,679 --> 00:15:18,317
So we want to show that it is true
517
00:15:18,317 --> 00:15:19,952
that if you increase the number
518
00:15:19,952 --> 00:15:21,854
of cities, number of sites,
519
00:15:22,121 --> 00:15:24,623
we actually can improve the signal
520
00:15:24,623 --> 00:15:25,991
that we obtain.
521
00:15:25,991 --> 00:15:28,894
So just we have a much better sensor
522
00:15:29,061 --> 00:15:31,463
that works and then can actually
523
00:15:31,497 --> 00:15:33,933
detect very, very, very small signals.
524
00:15:33,933 --> 00:15:35,601
So that's what we are doing.
525
00:15:35,668 --> 00:15:37,136
We already have the property.
526
00:15:37,202 --> 00:15:38,537
We know the material shows
527
00:15:38,671 --> 00:15:40,306
non Hermitian properties.
528
00:15:40,439 --> 00:15:42,775
Now the challenges make the sensors
529
00:15:42,775 --> 00:15:44,143
show that this
530
00:15:44,143 --> 00:15:45,544
theoretical prediction
531
00:15:45,544 --> 00:15:48,147
that you increasing the number of leads
532
00:15:48,147 --> 00:15:50,950
to enhancement of sensitivity does work.
533
00:15:50,983 --> 00:15:52,618
And that is what my students
534
00:15:52,618 --> 00:15:54,420
are working on right now in the lab
535
00:15:54,453 --> 00:15:55,921
trying to scale it up
536
00:15:55,921 --> 00:15:58,424
and then look at the sensitivity
537
00:15:58,424 --> 00:16:00,292
is scaling with the number of sites.
538
00:16:00,626 --> 00:16:02,161
You mentioned the students in your lab.
539
00:16:02,161 --> 00:16:03,062
And I want to,
540
00:16:03,062 --> 00:16:04,063
for the next couple of questions,
541
00:16:04,063 --> 00:16:04,463
kind of go
542
00:16:04,463 --> 00:16:05,698
a little broader to the other work
543
00:16:05,731 --> 00:16:06,265
you're doing.
544
00:16:06,265 --> 00:16:07,933
I know education
545
00:16:07,933 --> 00:16:09,435
and outreach is really important.
546
00:16:09,435 --> 00:16:09,868
In your lab.
547
00:16:09,868 --> 00:16:10,836
You have a number of programs
548
00:16:10,836 --> 00:16:11,136
you've done.
549
00:16:11,136 --> 00:16:12,638
Can you talk a little bit about this?
550
00:16:12,671 --> 00:16:13,138
Oh, yeah.
551
00:16:13,138 --> 00:16:15,741
So when I started telling you
552
00:16:15,741 --> 00:16:18,210
about what my lab does, I mentioned
553
00:16:18,277 --> 00:16:19,545
this idea
554
00:16:19,545 --> 00:16:21,580
that we are at the intersection
555
00:16:21,580 --> 00:16:23,382
of materials science,
556
00:16:23,382 --> 00:16:24,950
engineering, physics.
557
00:16:24,950 --> 00:16:26,986
So as you can imagine,
558
00:16:26,986 --> 00:16:28,721
people who are working my lab
559
00:16:28,721 --> 00:16:30,756
and doing these quantum property
560
00:16:30,756 --> 00:16:32,458
measurements and studies,
561
00:16:32,491 --> 00:16:34,026
they need to have certain
562
00:16:34,026 --> 00:16:35,227
skill sets.
563
00:16:35,227 --> 00:16:37,596
So it is very important for us
564
00:16:37,629 --> 00:16:39,198
to educate our student
565
00:16:39,231 --> 00:16:40,599
to a degree that they
566
00:16:40,632 --> 00:16:41,867
they're not just, you know,
567
00:16:41,900 --> 00:16:42,935
one dimensionally
568
00:16:42,935 --> 00:16:44,403
looking at, okay, I'm an engineer.
569
00:16:44,403 --> 00:16:46,271
I only need to know engineering, right.
570
00:16:46,338 --> 00:16:48,374
That kind of student would not
571
00:16:49,108 --> 00:16:51,810
usually succeed in the environment,
572
00:16:51,810 --> 00:16:53,779
such as my lab, because they need to know
573
00:16:53,779 --> 00:16:54,980
about the material.
574
00:16:55,080 --> 00:16:55,748
What?
575
00:16:55,748 --> 00:16:56,949
What it is that you need to do
576
00:16:56,949 --> 00:16:58,717
to improve the material property.
577
00:16:58,751 --> 00:17:00,352
They need to know about the devices,
578
00:17:00,352 --> 00:17:02,221
what kind of devices you need to make,
579
00:17:02,254 --> 00:17:03,555
and then you need to
580
00:17:03,589 --> 00:17:04,456
they need to also know
581
00:17:04,456 --> 00:17:05,791
about the physics of it.
582
00:17:05,791 --> 00:17:08,227
So whatever I'm doing, how does it change
583
00:17:08,260 --> 00:17:10,295
the underlying physics
584
00:17:10,295 --> 00:17:13,132
that governs the behavior of this device.
585
00:17:13,132 --> 00:17:16,135
So we need to have a quite diverse
586
00:17:16,135 --> 00:17:17,302
set of skills.
587
00:17:17,302 --> 00:17:20,472
So it is a very important
588
00:17:20,572 --> 00:17:22,241
to me, and I believe
589
00:17:22,274 --> 00:17:23,842
to a lot of my colleagues,
590
00:17:23,842 --> 00:17:25,477
to educate the students
591
00:17:25,477 --> 00:17:26,912
so that they have
592
00:17:28,213 --> 00:17:29,948
the diversity that we need
593
00:17:29,982 --> 00:17:32,751
to help us get these devices.
594
00:17:32,751 --> 00:17:35,187
And one of the things that I do in my lab
595
00:17:35,220 --> 00:17:37,556
to achieve that is to get
596
00:17:37,589 --> 00:17:38,957
undergraduate students
597
00:17:38,957 --> 00:17:40,726
involve early on in the lab.
598
00:17:40,759 --> 00:17:42,461
So over the past several years,
599
00:17:42,461 --> 00:17:44,630
I always had a couple of undergrads
600
00:17:44,630 --> 00:17:46,832
working with my grad students in the lab
601
00:17:46,832 --> 00:17:48,133
so that they can gain
602
00:17:48,133 --> 00:17:49,501
some exposure
603
00:17:49,501 --> 00:17:51,003
to what it is that we do,
604
00:17:51,036 --> 00:17:52,171
what kind of skill sets
605
00:17:52,171 --> 00:17:53,739
they need to be successful
606
00:17:53,739 --> 00:17:55,574
in, like my area,
607
00:17:55,641 --> 00:17:57,342
and then they can decide
608
00:17:57,376 --> 00:17:59,945
how to, you know, schedule their courses
609
00:17:59,945 --> 00:18:02,081
around the type of skills that they need.
610
00:18:02,114 --> 00:18:03,582
So this is kind of like the approach
611
00:18:03,582 --> 00:18:04,783
that I've taken with
612
00:18:04,783 --> 00:18:06,118
the graduate
613
00:18:06,151 --> 00:18:08,620
undergraduate education and outreach.
614
00:18:08,720 --> 00:18:09,822
I also want to ask you
615
00:18:09,822 --> 00:18:11,056
about NSF support.
616
00:18:11,056 --> 00:18:12,458
Can you talk a little bit about what
617
00:18:12,491 --> 00:18:14,660
difference that has made to your work?
618
00:18:14,660 --> 00:18:16,028
I would say it's huge.
619
00:18:16,028 --> 00:18:17,296
The materials
620
00:18:17,296 --> 00:18:18,497
that we used here,
621
00:18:18,530 --> 00:18:19,765
these quantum anomalous Hall insulators
622
00:18:20,132 --> 00:18:21,900
are developed in this center
623
00:18:21,934 --> 00:18:24,436
that was supported for many years by NSF.
624
00:18:24,636 --> 00:18:26,105
It's called two Dimensional
625
00:18:26,105 --> 00:18:27,739
Crystal consortium.
626
00:18:28,040 --> 00:18:30,442
It's a material innovation platform
627
00:18:30,442 --> 00:18:32,511
that NSF started, I think
628
00:18:32,878 --> 00:18:35,080
now 20 years ago at Penn State.
629
00:18:35,080 --> 00:18:38,350
And as part of that 2DCC, we call it
630
00:18:38,517 --> 00:18:39,585
short for what
631
00:18:39,585 --> 00:18:40,953
I just named.
632
00:18:40,986 --> 00:18:42,187
So as part of that
633
00:18:42,654 --> 00:18:43,555
my colleague
634
00:18:43,555 --> 00:18:44,756
Doctor Samarth
635
00:18:44,823 --> 00:18:46,658
developed these materials
636
00:18:46,658 --> 00:18:49,061
that show quantum insulators,
637
00:18:49,061 --> 00:18:51,363
and they kindly provided that to us.
638
00:18:51,363 --> 00:18:53,065
So without NSF
639
00:18:53,065 --> 00:18:54,299
and then the collaboration
640
00:18:54,299 --> 00:18:55,501
with Doctor Samarth
641
00:18:55,501 --> 00:18:56,702
accessing these methods
642
00:18:56,702 --> 00:18:58,270
would not be possible for us.
643
00:18:58,303 --> 00:18:59,271
And on top of that,
644
00:18:59,271 --> 00:19:00,672
a couple of students on
645
00:19:00,672 --> 00:19:01,907
this project
646
00:19:01,907 --> 00:19:04,276
were supported by NSF.
647
00:19:04,543 --> 00:19:05,744
The idea
648
00:19:05,944 --> 00:19:07,713
behind this non
649
00:19:07,713 --> 00:19:09,715
Hermitian physics
650
00:19:09,715 --> 00:19:11,717
and exploring them in quantum,
651
00:19:11,717 --> 00:19:13,051
and also emerged
652
00:19:13,051 --> 00:19:14,853
from a support that we had
653
00:19:14,920 --> 00:19:16,421
from another
654
00:19:16,421 --> 00:19:18,190
center at Penn State,
655
00:19:18,557 --> 00:19:19,892
NSF supported center.
656
00:19:19,892 --> 00:19:22,060
It's a MRSEC center
657
00:19:22,060 --> 00:19:23,695
for nanoscale science.
658
00:19:23,695 --> 00:19:26,064
So we had a seed grant from that center.
659
00:19:26,064 --> 00:19:28,300
And that kind of a kick
660
00:19:28,300 --> 00:19:29,468
started the whole project.
661
00:19:29,468 --> 00:19:31,036
So I would say without NSF,
662
00:19:31,336 --> 00:19:33,438
this would not have been possible.
663
00:19:33,438 --> 00:19:35,741
Whatever we talked about so far,
664
00:19:35,841 --> 00:19:37,042
this is very,
665
00:19:37,109 --> 00:19:39,278
very crucial to have NSF support,
666
00:19:39,311 --> 00:19:40,345
especially supporting
667
00:19:40,345 --> 00:19:41,380
fundamental research,
668
00:19:41,380 --> 00:19:43,882
because you might not know
669
00:19:44,082 --> 00:19:45,617
what they might lead to,
670
00:19:45,717 --> 00:19:46,919
but who knows,
671
00:19:46,985 --> 00:19:48,220
ten years down the road,
672
00:19:48,253 --> 00:19:50,522
what we are doing right now might help.
673
00:19:50,556 --> 00:19:51,790
They take something tiny
674
00:19:51,790 --> 00:19:54,026
that we couldn't have detected before.
675
00:19:54,193 --> 00:19:56,595
So thinking about that feature impact,
676
00:19:56,595 --> 00:19:57,829
for my last question,
677
00:19:57,829 --> 00:19:59,264
I want to ask you,
678
00:19:59,264 --> 00:20:01,333
where are you excited to see
679
00:20:01,400 --> 00:20:02,401
quantum research,
680
00:20:02,401 --> 00:20:03,502
specifically in your lab,
681
00:20:03,502 --> 00:20:04,903
I suppose, and maybe broadly to
682
00:20:04,937 --> 00:20:06,772
if you want, where do you want to see it
683
00:20:06,772 --> 00:20:08,040
go in the next few years?
684
00:20:08,040 --> 00:20:09,107
So I would make this
685
00:20:09,107 --> 00:20:10,375
a very broad statement.
686
00:20:10,375 --> 00:20:12,144
I used to work a lot
687
00:20:12,177 --> 00:20:14,947
on making qubits resilient.
688
00:20:14,947 --> 00:20:15,881
I would call them.
689
00:20:15,881 --> 00:20:17,482
So this concept of fault
690
00:20:17,516 --> 00:20:19,618
tolerant quantum computing
691
00:20:19,618 --> 00:20:21,119
so that you don't
692
00:20:21,119 --> 00:20:22,454
have to worry about errors.
693
00:20:22,521 --> 00:20:24,122
And over the past several years,
694
00:20:24,122 --> 00:20:25,557
I would say we have made
695
00:20:25,557 --> 00:20:27,226
a lot of progress
696
00:20:27,259 --> 00:20:29,461
making quantum systems scalable so
697
00:20:29,494 --> 00:20:30,696
they’re like bigger.
698
00:20:30,829 --> 00:20:31,530
And
699
00:20:32,531 --> 00:20:33,999
what I'm really excited
700
00:20:33,999 --> 00:20:35,334
to see is hopefully
701
00:20:35,400 --> 00:20:36,635
we passed
702
00:20:36,635 --> 00:20:38,537
a bottleneck of fault tolerance.
703
00:20:38,537 --> 00:20:40,138
We get to a stage
704
00:20:40,138 --> 00:20:42,541
where qubits are resilient.
705
00:20:42,774 --> 00:20:45,110
We don't have to worry about errors,
706
00:20:45,110 --> 00:20:47,512
and that would enable us to actually
707
00:20:47,546 --> 00:20:48,880
see real impact,
708
00:20:48,914 --> 00:20:50,515
like quantum computers
709
00:20:50,515 --> 00:20:52,551
solving some of the fundamental problems
710
00:20:52,551 --> 00:20:53,952
that we have been dealing with.
711
00:20:53,952 --> 00:20:54,386
I don't know,
712
00:20:54,386 --> 00:20:56,021
maybe we find a cure for cancer.
713
00:20:56,021 --> 00:20:56,822
Who knows?
714
00:20:56,822 --> 00:20:58,690
I'm an optimist,
715
00:20:58,890 --> 00:21:01,493
so I'm not one of those people
716
00:21:01,493 --> 00:21:03,228
who think quantum is a hype.
717
00:21:03,262 --> 00:21:04,463
I believe
718
00:21:04,563 --> 00:21:06,198
we have made real progress
719
00:21:06,198 --> 00:21:08,233
and given more opportunities.
720
00:21:08,233 --> 00:21:09,434
I believe
721
00:21:09,501 --> 00:21:10,802
there is a future
722
00:21:10,802 --> 00:21:12,337
where quantum computing
723
00:21:12,337 --> 00:21:13,872
could shine in certain
724
00:21:13,872 --> 00:21:16,308
areas of our life.
725
00:21:16,675 --> 00:21:18,610
Special thanks to Morteza Kayyalha.
726
00:21:18,677 --> 00:21:19,978
For the Discovery Files, I'm
727
00:21:20,012 --> 00:21:20,779
Nate Pottker.
728
00:21:20,779 --> 00:21:21,313
Watch video
729
00:21:21,313 --> 00:21:22,681
versions of these conversations
730
00:21:22,681 --> 00:21:24,816
on our @NSFScience YouTube channel.
731
00:21:24,883 --> 00:21:25,617
Please subscribe
732
00:21:25,617 --> 00:21:26,818
wherever you get podcasts
733
00:21:26,818 --> 00:21:28,253
and if you like our program, share
734
00:21:28,253 --> 00:21:29,154
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735
00:21:29,154 --> 00:21:30,722
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736
00:21:31,857 --> 00:21:32,758
Discover how the U.S.
737
00:21:32,758 --> 00:21:33,825
National Science Foundation
738
00:21:33,825 --> 00:21:35,027
is advancing research
739
00:21:35,027 --> 00:21:36,461
at NSF.gov.
00:00:03,503 --> 00:00:04,938
This is the Discovery Files
2
00:00:04,938 --> 00:00:06,239
podcast from the U.S.
3
00:00:06,239 --> 00:00:07,907
National Science Foundation.
4
00:00:09,909 --> 00:00:11,378
Materials research has yielded
5
00:00:11,378 --> 00:00:12,412
countless breakthroughs,
6
00:00:12,412 --> 00:00:14,180
from silicon semiconductors
7
00:00:14,180 --> 00:00:15,548
to the hydrogels used in
8
00:00:15,548 --> 00:00:17,584
contact lenses and wound dressings.
9
00:00:17,650 --> 00:00:19,319
NSF investments are advancing
10
00:00:19,319 --> 00:00:21,254
the golden age of American innovation
11
00:00:21,254 --> 00:00:22,589
through the development of critical
12
00:00:22,589 --> 00:00:23,957
and emerging technologies,
13
00:00:23,957 --> 00:00:25,792
including artificial intelligence,
14
00:00:25,792 --> 00:00:27,460
biotechnologies, and quantum
15
00:00:27,460 --> 00:00:28,762
information science.
16
00:00:28,895 --> 00:00:31,297
We're joined today by Morteza Kayyalha,
17
00:00:31,431 --> 00:00:33,099
an NSF-supported researcher
18
00:00:33,099 --> 00:00:34,401
whose Quantum Devices Lab
19
00:00:34,401 --> 00:00:36,903
focuses on electrical, thermoelectric,
20
00:00:36,903 --> 00:00:38,371
and superconducting properties
21
00:00:38,371 --> 00:00:39,539
of quantum materials.
22
00:00:39,539 --> 00:00:40,640
Professor Kayyalha
23
00:00:40,640 --> 00:00:42,042
thank you so much for joining me today.
24
00:00:42,175 --> 00:00:43,176
Thanks for having me.
25
00:00:43,176 --> 00:00:44,110
I appreciate it.
26
00:00:44,110 --> 00:00:44,411
We're going
27
00:00:44,411 --> 00:00:46,179
to get into some dense stuff here.
28
00:00:46,179 --> 00:00:47,514
So I want to start with
29
00:00:47,547 --> 00:00:49,315
kind of a definition for a public
30
00:00:49,349 --> 00:00:50,917
that is only hearing the term
31
00:00:50,917 --> 00:00:52,786
and doesn't really have a grasp of it,
32
00:00:52,819 --> 00:00:55,155
can you broadly define quantum?
33
00:00:55,155 --> 00:00:57,290
So quantum is
34
00:00:57,824 --> 00:01:00,593
basically the laws that we use
35
00:01:00,593 --> 00:01:01,795
to describe nature
36
00:01:01,795 --> 00:01:03,163
at the small scale.
37
00:01:03,830 --> 00:01:04,798
Things when they
38
00:01:04,798 --> 00:01:06,066
when they become small,
39
00:01:06,099 --> 00:01:07,600
they behave kind of like
40
00:01:07,634 --> 00:01:08,835
weirdly,
41
00:01:08,835 --> 00:01:10,737
that is not very intuitive to us,
42
00:01:10,770 --> 00:01:12,072
like human beings.
43
00:01:12,272 --> 00:01:14,441
For example, you can have what we call
44
00:01:14,441 --> 00:01:15,642
a superposition.
45
00:01:15,642 --> 00:01:18,278
And the best example I have
46
00:01:18,311 --> 00:01:20,080
that kind of like describe
47
00:01:20,080 --> 00:01:22,615
superposition is when you toss a coin,
48
00:01:23,016 --> 00:01:25,418
you expect to get heads or tails.
49
00:01:25,785 --> 00:01:27,720
But imagine you toss a coin
50
00:01:27,720 --> 00:01:30,123
and it just starts spinning.
51
00:01:30,323 --> 00:01:32,592
So it's neither tails
52
00:01:33,460 --> 00:01:34,794
or heads.
53
00:01:34,961 --> 00:01:36,096
So that's kind of
54
00:01:36,096 --> 00:01:38,465
like a quantum state, quantum system
55
00:01:38,465 --> 00:01:40,233
in a superposition state.
56
00:01:40,400 --> 00:01:42,802
We can have entanglements
57
00:01:42,802 --> 00:01:44,737
and coherence / decoherence.
58
00:01:44,737 --> 00:01:47,707
But in general quantum
59
00:01:47,707 --> 00:01:49,509
is how we describe things
60
00:01:49,509 --> 00:01:50,743
at a small scale.
61
00:01:50,810 --> 00:01:53,546
And then I want also noted a distinction
62
00:01:53,546 --> 00:01:55,482
that has become very important
63
00:01:55,515 --> 00:01:56,549
these days is
64
00:01:57,584 --> 00:01:58,585
like we used to have
65
00:01:58,585 --> 00:01:59,986
quantum mechanics.
66
00:02:00,053 --> 00:02:01,554
So that's I would call
67
00:02:01,554 --> 00:02:03,256
the first quantum revolution,
68
00:02:03,323 --> 00:02:04,390
like back in the day
69
00:02:04,390 --> 00:02:06,192
when transistors were invented.
70
00:02:06,192 --> 00:02:08,628
And that's the computer age.
71
00:02:08,862 --> 00:02:09,796
We have computers,
72
00:02:09,796 --> 00:02:11,331
we have cell phones and everything,
73
00:02:11,397 --> 00:02:12,632
every devices that we have
74
00:02:12,632 --> 00:02:14,300
in those tools,
75
00:02:14,300 --> 00:02:16,002
they use quantum mechanics.
76
00:02:16,002 --> 00:02:17,070
But nowadays
77
00:02:17,070 --> 00:02:18,705
when we use the word quantum,
78
00:02:18,705 --> 00:02:20,240
we are kind of like referring to
79
00:02:20,273 --> 00:02:21,875
something is slightly different.
80
00:02:21,875 --> 00:02:23,076
And that's I would
81
00:02:23,076 --> 00:02:25,478
use the term quantum information
82
00:02:25,478 --> 00:02:27,580
science or quantum computing.
83
00:02:27,747 --> 00:02:30,016
And they're what we are referring to
84
00:02:30,083 --> 00:02:32,318
is like a new generation of computers
85
00:02:32,318 --> 00:02:34,721
and new ways of communication
86
00:02:34,754 --> 00:02:36,156
that relies mostly
87
00:02:36,156 --> 00:02:38,658
on fundamental quantum properties
88
00:02:38,658 --> 00:02:41,161
like superposition, like entanglement,
89
00:02:41,194 --> 00:02:42,762
things that we didn't
90
00:02:42,762 --> 00:02:44,397
necessarily leverage
91
00:02:44,931 --> 00:02:46,132
when we were making,
92
00:02:46,199 --> 00:02:48,001
like the laptops that we have
93
00:02:48,034 --> 00:02:50,470
or this camera that I'm speaking to.
94
00:02:50,537 --> 00:02:53,239
So that's a distinction that I think
95
00:02:53,239 --> 00:02:54,174
a general public
96
00:02:54,174 --> 00:02:56,543
would appreciate being aware of.
97
00:02:56,576 --> 00:02:57,911
Very much cutting edge
98
00:02:57,911 --> 00:02:59,746
of where technology is right now.
99
00:02:59,779 --> 00:03:00,780
That's correct, yes.
100
00:03:00,780 --> 00:03:02,482
So thinking about that technology,
101
00:03:02,482 --> 00:03:03,516
I would like to ask you
102
00:03:03,516 --> 00:03:05,518
how you're working with quantum devices
103
00:03:05,518 --> 00:03:07,320
and quantum materials in your lab.
104
00:03:07,353 --> 00:03:09,189
In my lab we use materials,
105
00:03:09,189 --> 00:03:11,357
and then we either
106
00:03:11,357 --> 00:03:12,859
develop them ourselves in the lab,
107
00:03:12,859 --> 00:03:14,093
or we collaborate
108
00:03:14,093 --> 00:03:15,428
with materials scientists
109
00:03:15,428 --> 00:03:16,629
who kind of, like,
110
00:03:16,663 --> 00:03:18,298
create these new materials.
111
00:03:18,298 --> 00:03:20,934
And then we make new devices out of them.
112
00:03:20,934 --> 00:03:22,635
And the goal of the devices
113
00:03:22,635 --> 00:03:24,070
is just to study
114
00:03:24,170 --> 00:03:26,039
some of these quantum properties.
115
00:03:26,039 --> 00:03:27,707
So the materials and devices
116
00:03:27,707 --> 00:03:28,875
that we are interested in
117
00:03:28,875 --> 00:03:30,310
and we are exploring
118
00:03:30,376 --> 00:03:31,911
are those that,
119
00:03:31,911 --> 00:03:33,546
in some way or another,
120
00:03:33,713 --> 00:03:35,281
have some potential
121
00:03:35,315 --> 00:03:37,217
to exhibit properties
122
00:03:37,217 --> 00:03:38,585
that are kind of like new
123
00:03:38,618 --> 00:03:39,919
or unexpected
124
00:03:39,953 --> 00:03:41,754
when it comes to quantum scale.
125
00:03:41,788 --> 00:03:45,024
And then we mostly study
126
00:03:45,024 --> 00:03:47,227
the fundamental properties in the lab,
127
00:03:47,493 --> 00:03:49,195
but then we have our eyes
128
00:03:49,229 --> 00:03:51,898
set in some of the applications
129
00:03:51,898 --> 00:03:54,234
that these fundamental properties
130
00:03:54,234 --> 00:03:56,002
might enable in the future.
131
00:03:56,035 --> 00:03:57,370
Like, for example, can
132
00:03:57,370 --> 00:03:59,272
we develop a new material
133
00:03:59,439 --> 00:04:00,873
and make a new device
134
00:04:00,873 --> 00:04:02,909
that might lead to
135
00:04:02,909 --> 00:04:04,210
a quantum computer
136
00:04:04,210 --> 00:04:05,745
that is not noisy
137
00:04:06,145 --> 00:04:07,981
or can help
138
00:04:07,981 --> 00:04:09,582
scale up the quantum system?
139
00:04:09,582 --> 00:04:11,017
So we have
140
00:04:11,017 --> 00:04:12,652
those general goals in mind.
141
00:04:12,652 --> 00:04:14,320
But in the lab, we overall
142
00:04:14,320 --> 00:04:15,922
work with materials and devices.
143
00:04:15,955 --> 00:04:17,657
It's the intersection between
144
00:04:17,657 --> 00:04:18,992
material science,
145
00:04:19,425 --> 00:04:20,426
device physic,
146
00:04:20,426 --> 00:04:21,995
electrical engineering
147
00:04:22,228 --> 00:04:23,429
and quantum physics.
148
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So we have like
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a very nice
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interdisciplinary research
151
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going on in the lab.
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Moving into the work
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that brought you to my attention today.
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You have a recently published paper,
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and there's a couple specific areas of it
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that are important to explaining
157
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what you're doing that
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00:04:39,412 --> 00:04:41,881
I think we need to examine a little bit.
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00:04:41,881 --> 00:04:43,383
And I want to ask you, what are non
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Hermitian physics?
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00:04:44,917 --> 00:04:47,587
Non-Hermitian physics like generally
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when we talk about quantum, quantum
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systems,
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we have this rule.
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00:04:52,392 --> 00:04:54,093
We call it like a closed box.
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00:04:54,093 --> 00:04:55,962
So imagine a system
167
00:04:55,962 --> 00:04:57,163
that is isolated from
168
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its environment is just
169
00:04:58,331 --> 00:04:59,999
sitting there in isolation.
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00:04:59,999 --> 00:05:02,235
And then the study is property.
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That's the gist of a Hermitian system.
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But in reality
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what happens is
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the system is never fully isolated.
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It communicates with its environment,
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is in interaction
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with the with the environment.
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And as a result of this interaction
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or these interactions,
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it gains energy or loses some energy.
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So there are like gain and losses
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that are involved
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because of these interactions
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that the system has with the environment.
185
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And as a result of that,
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you get these things that we call
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non Hermitian physics.
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00:05:33,499 --> 00:05:35,601
And why they're interesting
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00:05:35,601 --> 00:05:38,171
is non Hermitian systems
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00:05:38,171 --> 00:05:39,505
can have their own kind
191
00:05:39,505 --> 00:05:41,274
of like uniqueness.
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00:05:41,307 --> 00:05:43,743
They can lead to a properties
193
00:05:43,743 --> 00:05:44,944
that you would otherwise
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00:05:44,944 --> 00:05:45,912
not observe
195
00:05:45,912 --> 00:05:47,880
in a Hermitian system, in a system
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that is completely closed.
197
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For example,
198
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one is what
199
00:05:52,385 --> 00:05:54,954
we actually studied in this paper
200
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called the non Hermitian skin effect.
201
00:05:57,490 --> 00:05:59,692
And what that means is that for example,
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in our case,
203
00:06:00,893 --> 00:06:02,428
electrical current
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is getting localized
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in one end of a chain
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instead of being
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uniformly distributed across the chain.
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Or you can
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you can have this localization emerging
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variety of different ways.
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That's why we call it a skin effects.
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00:06:18,311 --> 00:06:19,579
Like in a wire,
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if a current is only on
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00:06:21,114 --> 00:06:22,548
the surface of the wire,
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you have a skin effect.
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00:06:24,050 --> 00:06:25,385
So it's like the current
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00:06:25,385 --> 00:06:26,652
is not inside
218
00:06:26,652 --> 00:06:28,221
the wire is only on the surface.
219
00:06:28,221 --> 00:06:29,455
So it's kind of like this
220
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localization property.
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And this can have its own application
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00:06:33,393 --> 00:06:35,461
whenever you want to do sensing later on.
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So, part of the interest in my lab
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with a non Hermitian
225
00:06:40,133 --> 00:06:41,801
physics is what kind of new
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properties can be discovered.
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And then the next question is
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how can we connect them
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to applications.
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So moving into the applications
231
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I guess or the device
232
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quantum anomalous Hall insulators
233
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is the next one I want to ask you about.
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What are they and
235
00:06:57,116 --> 00:06:59,185
how might they be advantageous.
236
00:06:59,318 --> 00:07:01,053
Quantum anomalous Hall insulators.
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The name anomalous
238
00:07:02,989 --> 00:07:04,190
is basically telling
239
00:07:04,190 --> 00:07:05,558
us that it's a quantum
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Hall insulator, but it's anomalous.
241
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But I understand that for somebody
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00:07:09,595 --> 00:07:10,797
listening to this
243
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quantum Hall
244
00:07:12,532 --> 00:07:15,201
might also be as strange of a name.
245
00:07:15,201 --> 00:07:17,036
So maybe the best way
246
00:07:17,036 --> 00:07:18,371
I can explain
247
00:07:18,371 --> 00:07:19,739
this is typically
248
00:07:19,739 --> 00:07:21,073
the materials that we work with
249
00:07:21,073 --> 00:07:22,542
are in three dimensions,
250
00:07:22,575 --> 00:07:24,143
like everything is big,
251
00:07:24,310 --> 00:07:26,179
but then imagine you
252
00:07:26,212 --> 00:07:28,614
scale the thickness down to
253
00:07:29,816 --> 00:07:31,951
feel nanometers, tens of nanometers.
254
00:07:31,951 --> 00:07:34,921
So those in that scale range,
255
00:07:34,987 --> 00:07:36,556
we get to systems
256
00:07:36,556 --> 00:07:37,824
that we can kind of like
257
00:07:37,857 --> 00:07:39,692
call them two dimensional.
258
00:07:39,759 --> 00:07:42,061
So the thickness is no longer
259
00:07:42,094 --> 00:07:42,962
very important.
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00:07:42,962 --> 00:07:44,130
It's mostly
261
00:07:44,263 --> 00:07:46,466
the trans or the electrical current.
262
00:07:46,466 --> 00:07:48,434
Electricity is carried
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00:07:48,468 --> 00:07:50,069
along the 2D
264
00:07:50,336 --> 00:07:52,271
surface of the system.
265
00:07:52,738 --> 00:07:55,141
So in those type of materials,
266
00:07:55,141 --> 00:07:56,776
if you thin them down
267
00:07:57,109 --> 00:07:58,544
we call them two dimensional
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materials basically,
269
00:08:00,012 --> 00:08:02,548
or two dimensional electron systems.
270
00:08:02,548 --> 00:08:04,250
In those systems if you apply
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very strong magnetic field,
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00:08:05,618 --> 00:08:07,186
what happens is
273
00:08:07,720 --> 00:08:10,189
you get this quantum Hall insulator.
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00:08:10,189 --> 00:08:11,591
And what that means
275
00:08:11,624 --> 00:08:13,025
is simply
276
00:08:13,059 --> 00:08:14,894
electricity is only going
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00:08:14,961 --> 00:08:17,163
around the perimeter of the material,
278
00:08:17,597 --> 00:08:18,798
and the bulk
279
00:08:19,398 --> 00:08:20,600
is not carrying
280
00:08:20,666 --> 00:08:21,834
electricity.
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00:08:21,834 --> 00:08:23,636
So quantum anomalous Hall
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00:08:23,636 --> 00:08:25,071
insulator is a material
283
00:08:25,071 --> 00:08:26,506
that has electricity
284
00:08:26,506 --> 00:08:28,508
moving along its perimeter.
285
00:08:28,741 --> 00:08:31,077
The bulk has no electrical current
286
00:08:31,077 --> 00:08:33,279
and this happens
287
00:08:33,279 --> 00:08:34,480
without the magnetic field,
288
00:08:34,514 --> 00:08:36,282
thus the name anomalous.
289
00:08:36,282 --> 00:08:38,818
So quantum hall you need magnetic field.
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00:08:38,851 --> 00:08:40,453
Quantum anomalous Hall.
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00:08:40,520 --> 00:08:42,221
No magnetic field is needed.
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00:08:42,622 --> 00:08:43,656
And that's great
293
00:08:43,656 --> 00:08:46,459
because not having magnetic
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field removes
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00:08:47,960 --> 00:08:49,195
one of the limitation
296
00:08:49,228 --> 00:08:51,030
of using these materials
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for certain applications.
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00:08:53,065 --> 00:08:54,667
So mixing these things together,
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00:08:54,700 --> 00:08:56,235
can we talk about the device
300
00:08:56,235 --> 00:08:58,137
that you've put together in this paper.
301
00:08:58,170 --> 00:08:58,538
Sure.
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00:08:58,538 --> 00:09:01,073
So what we decided to do was
303
00:09:01,107 --> 00:09:02,575
look at these quantum
304
00:09:02,575 --> 00:09:04,110
anomalous insulators
305
00:09:04,110 --> 00:09:05,578
and then see whether
306
00:09:05,578 --> 00:09:07,346
they can build
307
00:09:07,346 --> 00:09:09,115
anything or create
308
00:09:09,115 --> 00:09:11,717
any non Hermitian properties in them.
309
00:09:11,717 --> 00:09:14,186
And the best way I can explain
310
00:09:14,186 --> 00:09:17,156
this is we created sites
311
00:09:17,189 --> 00:09:18,891
across this quantum
312
00:09:18,891 --> 00:09:20,226
anomalous insulators.
313
00:09:20,226 --> 00:09:22,695
And then we leverage this property
314
00:09:22,695 --> 00:09:25,398
that between the sites electricity
315
00:09:25,431 --> 00:09:27,867
only flows in one direction.
316
00:09:27,867 --> 00:09:31,237
So if I have imagine this size of cities,
317
00:09:31,270 --> 00:09:32,638
if I have two cities,
318
00:09:32,705 --> 00:09:33,873
there is a one way road
319
00:09:33,873 --> 00:09:34,874
connecting the city.
320
00:09:34,874 --> 00:09:37,443
So cars can go from City 1 to City two,
321
00:09:37,443 --> 00:09:38,744
but they cannot come back.
322
00:09:38,744 --> 00:09:40,479
And then what we showed
323
00:09:40,513 --> 00:09:42,014
was using
324
00:09:42,014 --> 00:09:43,516
this unique property
325
00:09:43,516 --> 00:09:44,717
that quantum and almost
326
00:09:44,717 --> 00:09:46,419
all insulated it provides for us.
327
00:09:46,452 --> 00:09:47,720
We can make
328
00:09:47,753 --> 00:09:50,356
or we can observe the non
329
00:09:50,356 --> 00:09:51,557
Hermitian skin effect
330
00:09:51,557 --> 00:09:52,692
that I was telling you about.
331
00:09:52,692 --> 00:09:54,260
So regardless of where
332
00:09:54,260 --> 00:09:55,461
I inject
333
00:09:55,494 --> 00:09:57,897
electricity in this device
334
00:09:57,930 --> 00:10:00,132
or in our example to
335
00:10:00,199 --> 00:10:01,534
if I want to use that example,
336
00:10:01,867 --> 00:10:03,903
regardless of where the cars are coming
337
00:10:04,303 --> 00:10:05,905
to the cities,
338
00:10:06,138 --> 00:10:07,306
whether they come to City
339
00:10:07,306 --> 00:10:08,574
A, City B, City
340
00:10:08,574 --> 00:10:09,976
C, so on and so forth.
341
00:10:10,042 --> 00:10:11,911
They all go and eventually
342
00:10:11,911 --> 00:10:13,112
end up
343
00:10:13,145 --> 00:10:14,547
the last city that we have.
344
00:10:14,580 --> 00:10:15,781
So it doesn't matter
345
00:10:15,781 --> 00:10:17,083
where
346
00:10:17,083 --> 00:10:18,417
at what point they enter
347
00:10:18,417 --> 00:10:19,785
the device.
348
00:10:19,819 --> 00:10:22,388
The electricity will always
349
00:10:22,388 --> 00:10:23,623
localize towards
350
00:10:23,623 --> 00:10:25,491
the end of the chain.
351
00:10:25,591 --> 00:10:27,093
And that's what we did.
352
00:10:27,093 --> 00:10:28,995
So we showed that
353
00:10:29,061 --> 00:10:30,363
in this quantum anomalous hall insulator
354
00:10:30,930 --> 00:10:32,732
we can observe this
355
00:10:32,798 --> 00:10:35,401
fundamental property that we call
356
00:10:35,534 --> 00:10:36,636
skin effect.
357
00:10:36,636 --> 00:10:38,070
So why would you want
358
00:10:38,070 --> 00:10:39,338
to bring this into
359
00:10:39,372 --> 00:10:40,506
say a competing system,
360
00:10:40,506 --> 00:10:42,975
why would this be useful in a computer?
361
00:10:43,042 --> 00:10:44,477
Oh that's a very good question.
362
00:10:44,477 --> 00:10:47,079
So there are people theorists
363
00:10:47,079 --> 00:10:48,547
who know more about these things,
364
00:10:48,547 --> 00:10:51,117
and they have predicted that
365
00:10:51,117 --> 00:10:53,252
if we create such a device
366
00:10:53,252 --> 00:10:56,155
that we have built in our lab, then
367
00:10:56,322 --> 00:10:58,491
depending on the number of sites
368
00:10:58,491 --> 00:10:59,992
that we have in the chains
369
00:11:00,026 --> 00:11:01,794
in this example, in my example,
370
00:11:01,794 --> 00:11:03,596
it would be number of cities.
371
00:11:03,896 --> 00:11:06,298
You get certain sensitivity
372
00:11:06,332 --> 00:11:07,900
if you perturb the system.
373
00:11:07,933 --> 00:11:09,835
Let's say you have a tiny electric field,
374
00:11:09,869 --> 00:11:10,936
tiny magnetic field
375
00:11:10,936 --> 00:11:12,438
that perturbs your system.
376
00:11:12,438 --> 00:11:15,141
And you want to measure the amplitude
377
00:11:15,141 --> 00:11:16,642
of that perturbation.
378
00:11:17,376 --> 00:11:19,078
The theoretical prediction is
379
00:11:19,078 --> 00:11:21,280
if you have ten cities in your device
380
00:11:21,280 --> 00:11:23,215
or ten sites in your device,
381
00:11:23,215 --> 00:11:25,251
you get certain amplification
382
00:11:25,251 --> 00:11:26,652
of that perturbation.
383
00:11:26,652 --> 00:11:28,320
But if you have 100,
384
00:11:28,354 --> 00:11:30,356
you get exponentially more
385
00:11:30,423 --> 00:11:31,624
amplification.
386
00:11:31,624 --> 00:11:33,459
So you can imagine doing
387
00:11:33,459 --> 00:11:36,228
sensing with this device.
388
00:11:36,395 --> 00:11:39,098
And the way your sensor would work is
389
00:11:39,098 --> 00:11:40,866
you can show by increasing
390
00:11:40,866 --> 00:11:42,468
the number of chains
391
00:11:42,468 --> 00:11:44,737
or the number of sites, number of cities.
392
00:11:44,737 --> 00:11:45,938
In my example,
393
00:11:46,272 --> 00:11:48,107
you have enhanced
394
00:11:48,107 --> 00:11:49,041
exponentially
395
00:11:49,041 --> 00:11:50,876
the sensitivity of your sensor.
396
00:11:50,876 --> 00:11:53,012
So this is quite extraordinary
397
00:11:53,012 --> 00:11:54,780
if it turns out to be true.
398
00:11:54,780 --> 00:11:56,148
And one of the advantages
399
00:11:56,148 --> 00:11:58,017
of this quantum and insulator
400
00:11:58,050 --> 00:11:59,251
that we have
401
00:11:59,318 --> 00:12:01,921
is that it is relatively easy to
402
00:12:02,054 --> 00:12:02,822
scale it up.
403
00:12:02,822 --> 00:12:05,391
So making two cities, two sites,
404
00:12:05,458 --> 00:12:07,059
three, four, five
405
00:12:07,259 --> 00:12:08,861
is relatively straightforward
406
00:12:08,861 --> 00:12:10,229
because we use something called
407
00:12:10,229 --> 00:12:11,630
nanofabrication.
408
00:12:11,664 --> 00:12:12,865
This is a technology
409
00:12:12,865 --> 00:12:15,868
we use to make our laptops,
410
00:12:15,868 --> 00:12:17,336
the fabs,
411
00:12:17,703 --> 00:12:19,071
they create these transistors.
412
00:12:19,071 --> 00:12:20,139
So it's very straightforward.
413
00:12:20,139 --> 00:12:22,742
We have all the toolsets available
414
00:12:22,908 --> 00:12:24,844
so that we can easily scale them
415
00:12:24,844 --> 00:12:26,879
on going from ten sites to 20 site
416
00:12:26,912 --> 00:12:29,882
to 100 site to maybe 1000 sites.
417
00:12:29,882 --> 00:12:32,118
And if the amplification,
418
00:12:32,118 --> 00:12:34,019
if this sensitivity enhancement
419
00:12:34,019 --> 00:12:35,755
is turns out to be true,
420
00:12:35,855 --> 00:12:38,257
then you can have very many
421
00:12:38,657 --> 00:12:39,859
signal coming in
422
00:12:39,859 --> 00:12:41,627
and then amplified
423
00:12:41,627 --> 00:12:43,028
by quite a lot
424
00:12:43,028 --> 00:12:44,864
and do sensing of it
425
00:12:44,864 --> 00:12:46,065
basically measure
426
00:12:46,132 --> 00:12:47,933
that small signal.
427
00:12:47,933 --> 00:12:50,669
So that's the whole excitement
428
00:12:50,703 --> 00:12:51,904
that I had.
429
00:12:51,971 --> 00:12:53,572
This is how I got into this,
430
00:12:54,106 --> 00:12:55,374
this field, basically.
431
00:12:55,441 --> 00:12:56,976
You mentioned the nanofabrication,
432
00:12:56,976 --> 00:12:58,010
and I'm thinking about
433
00:12:58,010 --> 00:12:59,345
some of the challenges
434
00:12:59,345 --> 00:13:00,713
working at the quantum scale.
435
00:13:00,746 --> 00:13:01,747
Can you talk a little bit
436
00:13:01,747 --> 00:13:03,349
about the challenges
437
00:13:03,349 --> 00:13:04,550
developing this?
438
00:13:04,717 --> 00:13:06,519
Well, one of the biggest challenges
439
00:13:06,519 --> 00:13:07,720
that we haven't
440
00:13:07,720 --> 00:13:08,954
addressed yet
441
00:13:08,988 --> 00:13:10,189
is with the quantum
442
00:13:10,523 --> 00:13:11,957
anomalous Hall insulator itself.
443
00:13:11,957 --> 00:13:14,293
So these materials,
444
00:13:14,360 --> 00:13:14,794
these
445
00:13:14,794 --> 00:13:16,228
the property that I told you,
446
00:13:16,228 --> 00:13:17,630
the electricity flowing
447
00:13:17,630 --> 00:13:19,665
around the perimeter of the device,
448
00:13:20,065 --> 00:13:22,401
only images at very,
449
00:13:22,401 --> 00:13:23,803
very low temperatures.
450
00:13:23,803 --> 00:13:25,704
So we are getting close
451
00:13:25,704 --> 00:13:27,473
to the absolute zero temperature,
452
00:13:27,506 --> 00:13:28,707
like very, very cold,
453
00:13:28,774 --> 00:13:29,909
colder than anything
454
00:13:29,909 --> 00:13:31,377
that anybody can imagine.
455
00:13:31,377 --> 00:13:33,345
So that's a big challenge
456
00:13:33,345 --> 00:13:34,880
because if you want to have
457
00:13:34,880 --> 00:13:36,148
real applications
458
00:13:36,148 --> 00:13:38,217
that would improve our lives
459
00:13:38,317 --> 00:13:39,585
in a meaningful way,
460
00:13:39,652 --> 00:13:41,453
we want things to be done at room
461
00:13:41,520 --> 00:13:41,954
temperature,
462
00:13:41,954 --> 00:13:43,589
like I'm sitting in this room,
463
00:13:43,589 --> 00:13:45,357
I want my quantum
464
00:13:45,558 --> 00:13:46,292
anomalous Hall insulator
465
00:13:46,292 --> 00:13:47,626
to work at this temperature.
466
00:13:47,626 --> 00:13:50,396
And one of the things that we need
467
00:13:50,396 --> 00:13:52,264
to improve to achieve this goal
468
00:13:52,264 --> 00:13:52,698
is to
469
00:13:52,698 --> 00:13:54,834
improve the quality of the material.
470
00:13:54,834 --> 00:13:57,102
So these materials need to be very pure.
471
00:13:57,136 --> 00:13:58,871
But the challenge is,
472
00:13:59,071 --> 00:14:00,539
at least for us, the quantum
473
00:14:00,539 --> 00:14:01,640
anomalous Hall insulators
474
00:14:01,640 --> 00:14:03,542
that we use are doped.
475
00:14:03,576 --> 00:14:05,711
So they have certain level of impurity.
476
00:14:05,711 --> 00:14:08,280
And this impurity is required
477
00:14:08,714 --> 00:14:09,682
to get the name
478
00:14:09,682 --> 00:14:11,383
anomalous in our quantum
479
00:14:11,383 --> 00:14:12,751
anomalous Hall insulator.
480
00:14:12,785 --> 00:14:14,920
To basically not have any magnetic field
481
00:14:14,954 --> 00:14:16,622
we need to add these impurities.
482
00:14:16,622 --> 00:14:18,057
So the challenge
483
00:14:18,057 --> 00:14:19,491
becomes is a trade off.
484
00:14:19,558 --> 00:14:21,193
I need to add the impurity
485
00:14:21,193 --> 00:14:23,195
so that I don't need the magnetic field.
486
00:14:23,229 --> 00:14:24,864
But the impurity makes
487
00:14:24,864 --> 00:14:26,332
my material not pure.
488
00:14:26,398 --> 00:14:28,801
So that causes the relation
489
00:14:28,801 --> 00:14:30,302
of the material quality.
490
00:14:30,302 --> 00:14:31,704
So I have to kind of like
491
00:14:31,737 --> 00:14:33,539
find the optimal point.
492
00:14:33,539 --> 00:14:34,940
And this is something that
493
00:14:34,974 --> 00:14:36,442
my colleagues at Penn
494
00:14:36,442 --> 00:14:37,676
State are working on
495
00:14:37,710 --> 00:14:40,079
to enhance and improve.
496
00:14:40,112 --> 00:14:42,214
So we can have better,
497
00:14:42,214 --> 00:14:43,782
higher quality materials.
498
00:14:43,782 --> 00:14:44,617
And as a result,
499
00:14:44,617 --> 00:14:46,585
we can have these materials
500
00:14:46,585 --> 00:14:47,987
exhibiting these properties
501
00:14:48,020 --> 00:14:50,422
at closer to room temperatures.
502
00:14:50,422 --> 00:14:52,424
Basically, that would be the the goal.
503
00:14:52,424 --> 00:14:53,592
I would say.
504
00:14:53,592 --> 00:14:56,028
Right, you have to make some compromises
505
00:14:56,028 --> 00:14:57,897
to get the things to work
506
00:14:57,897 --> 00:14:58,797
with, the attributes
507
00:14:58,797 --> 00:15:00,799
you want them to have, and for all of us
508
00:15:00,799 --> 00:15:02,101
to play together nicely.
509
00:15:02,101 --> 00:15:03,235
So you talked a little
510
00:15:03,235 --> 00:15:05,571
bit of the challenges developing there.
511
00:15:05,638 --> 00:15:06,939
What are your next steps
512
00:15:06,939 --> 00:15:08,140
to move this towards
513
00:15:08,140 --> 00:15:10,576
potential commercial applications.
514
00:15:10,643 --> 00:15:11,777
So our next step
515
00:15:11,777 --> 00:15:13,579
is to just make the sensors.
516
00:15:13,679 --> 00:15:18,317
So we want to show that it is true
517
00:15:18,317 --> 00:15:19,952
that if you increase the number
518
00:15:19,952 --> 00:15:21,854
of cities, number of sites,
519
00:15:22,121 --> 00:15:24,623
we actually can improve the signal
520
00:15:24,623 --> 00:15:25,991
that we obtain.
521
00:15:25,991 --> 00:15:28,894
So just we have a much better sensor
522
00:15:29,061 --> 00:15:31,463
that works and then can actually
523
00:15:31,497 --> 00:15:33,933
detect very, very, very small signals.
524
00:15:33,933 --> 00:15:35,601
So that's what we are doing.
525
00:15:35,668 --> 00:15:37,136
We already have the property.
526
00:15:37,202 --> 00:15:38,537
We know the material shows
527
00:15:38,671 --> 00:15:40,306
non Hermitian properties.
528
00:15:40,439 --> 00:15:42,775
Now the challenges make the sensors
529
00:15:42,775 --> 00:15:44,143
show that this
530
00:15:44,143 --> 00:15:45,544
theoretical prediction
531
00:15:45,544 --> 00:15:48,147
that you increasing the number of leads
532
00:15:48,147 --> 00:15:50,950
to enhancement of sensitivity does work.
533
00:15:50,983 --> 00:15:52,618
And that is what my students
534
00:15:52,618 --> 00:15:54,420
are working on right now in the lab
535
00:15:54,453 --> 00:15:55,921
trying to scale it up
536
00:15:55,921 --> 00:15:58,424
and then look at the sensitivity
537
00:15:58,424 --> 00:16:00,292
is scaling with the number of sites.
538
00:16:00,626 --> 00:16:02,161
You mentioned the students in your lab.
539
00:16:02,161 --> 00:16:03,062
And I want to,
540
00:16:03,062 --> 00:16:04,063
for the next couple of questions,
541
00:16:04,063 --> 00:16:04,463
kind of go
542
00:16:04,463 --> 00:16:05,698
a little broader to the other work
543
00:16:05,731 --> 00:16:06,265
you're doing.
544
00:16:06,265 --> 00:16:07,933
I know education
545
00:16:07,933 --> 00:16:09,435
and outreach is really important.
546
00:16:09,435 --> 00:16:09,868
In your lab.
547
00:16:09,868 --> 00:16:10,836
You have a number of programs
548
00:16:10,836 --> 00:16:11,136
you've done.
549
00:16:11,136 --> 00:16:12,638
Can you talk a little bit about this?
550
00:16:12,671 --> 00:16:13,138
Oh, yeah.
551
00:16:13,138 --> 00:16:15,741
So when I started telling you
552
00:16:15,741 --> 00:16:18,210
about what my lab does, I mentioned
553
00:16:18,277 --> 00:16:19,545
this idea
554
00:16:19,545 --> 00:16:21,580
that we are at the intersection
555
00:16:21,580 --> 00:16:23,382
of materials science,
556
00:16:23,382 --> 00:16:24,950
engineering, physics.
557
00:16:24,950 --> 00:16:26,986
So as you can imagine,
558
00:16:26,986 --> 00:16:28,721
people who are working my lab
559
00:16:28,721 --> 00:16:30,756
and doing these quantum property
560
00:16:30,756 --> 00:16:32,458
measurements and studies,
561
00:16:32,491 --> 00:16:34,026
they need to have certain
562
00:16:34,026 --> 00:16:35,227
skill sets.
563
00:16:35,227 --> 00:16:37,596
So it is very important for us
564
00:16:37,629 --> 00:16:39,198
to educate our student
565
00:16:39,231 --> 00:16:40,599
to a degree that they
566
00:16:40,632 --> 00:16:41,867
they're not just, you know,
567
00:16:41,900 --> 00:16:42,935
one dimensionally
568
00:16:42,935 --> 00:16:44,403
looking at, okay, I'm an engineer.
569
00:16:44,403 --> 00:16:46,271
I only need to know engineering, right.
570
00:16:46,338 --> 00:16:48,374
That kind of student would not
571
00:16:49,108 --> 00:16:51,810
usually succeed in the environment,
572
00:16:51,810 --> 00:16:53,779
such as my lab, because they need to know
573
00:16:53,779 --> 00:16:54,980
about the material.
574
00:16:55,080 --> 00:16:55,748
What?
575
00:16:55,748 --> 00:16:56,949
What it is that you need to do
576
00:16:56,949 --> 00:16:58,717
to improve the material property.
577
00:16:58,751 --> 00:17:00,352
They need to know about the devices,
578
00:17:00,352 --> 00:17:02,221
what kind of devices you need to make,
579
00:17:02,254 --> 00:17:03,555
and then you need to
580
00:17:03,589 --> 00:17:04,456
they need to also know
581
00:17:04,456 --> 00:17:05,791
about the physics of it.
582
00:17:05,791 --> 00:17:08,227
So whatever I'm doing, how does it change
583
00:17:08,260 --> 00:17:10,295
the underlying physics
584
00:17:10,295 --> 00:17:13,132
that governs the behavior of this device.
585
00:17:13,132 --> 00:17:16,135
So we need to have a quite diverse
586
00:17:16,135 --> 00:17:17,302
set of skills.
587
00:17:17,302 --> 00:17:20,472
So it is a very important
588
00:17:20,572 --> 00:17:22,241
to me, and I believe
589
00:17:22,274 --> 00:17:23,842
to a lot of my colleagues,
590
00:17:23,842 --> 00:17:25,477
to educate the students
591
00:17:25,477 --> 00:17:26,912
so that they have
592
00:17:28,213 --> 00:17:29,948
the diversity that we need
593
00:17:29,982 --> 00:17:32,751
to help us get these devices.
594
00:17:32,751 --> 00:17:35,187
And one of the things that I do in my lab
595
00:17:35,220 --> 00:17:37,556
to achieve that is to get
596
00:17:37,589 --> 00:17:38,957
undergraduate students
597
00:17:38,957 --> 00:17:40,726
involve early on in the lab.
598
00:17:40,759 --> 00:17:42,461
So over the past several years,
599
00:17:42,461 --> 00:17:44,630
I always had a couple of undergrads
600
00:17:44,630 --> 00:17:46,832
working with my grad students in the lab
601
00:17:46,832 --> 00:17:48,133
so that they can gain
602
00:17:48,133 --> 00:17:49,501
some exposure
603
00:17:49,501 --> 00:17:51,003
to what it is that we do,
604
00:17:51,036 --> 00:17:52,171
what kind of skill sets
605
00:17:52,171 --> 00:17:53,739
they need to be successful
606
00:17:53,739 --> 00:17:55,574
in, like my area,
607
00:17:55,641 --> 00:17:57,342
and then they can decide
608
00:17:57,376 --> 00:17:59,945
how to, you know, schedule their courses
609
00:17:59,945 --> 00:18:02,081
around the type of skills that they need.
610
00:18:02,114 --> 00:18:03,582
So this is kind of like the approach
611
00:18:03,582 --> 00:18:04,783
that I've taken with
612
00:18:04,783 --> 00:18:06,118
the graduate
613
00:18:06,151 --> 00:18:08,620
undergraduate education and outreach.
614
00:18:08,720 --> 00:18:09,822
I also want to ask you
615
00:18:09,822 --> 00:18:11,056
about NSF support.
616
00:18:11,056 --> 00:18:12,458
Can you talk a little bit about what
617
00:18:12,491 --> 00:18:14,660
difference that has made to your work?
618
00:18:14,660 --> 00:18:16,028
I would say it's huge.
619
00:18:16,028 --> 00:18:17,296
The materials
620
00:18:17,296 --> 00:18:18,497
that we used here,
621
00:18:18,530 --> 00:18:19,765
these quantum anomalous Hall insulators
622
00:18:20,132 --> 00:18:21,900
are developed in this center
623
00:18:21,934 --> 00:18:24,436
that was supported for many years by NSF.
624
00:18:24,636 --> 00:18:26,105
It's called two Dimensional
625
00:18:26,105 --> 00:18:27,739
Crystal consortium.
626
00:18:28,040 --> 00:18:30,442
It's a material innovation platform
627
00:18:30,442 --> 00:18:32,511
that NSF started, I think
628
00:18:32,878 --> 00:18:35,080
now 20 years ago at Penn State.
629
00:18:35,080 --> 00:18:38,350
And as part of that 2DCC, we call it
630
00:18:38,517 --> 00:18:39,585
short for what
631
00:18:39,585 --> 00:18:40,953
I just named.
632
00:18:40,986 --> 00:18:42,187
So as part of that
633
00:18:42,654 --> 00:18:43,555
my colleague
634
00:18:43,555 --> 00:18:44,756
Doctor Samarth
635
00:18:44,823 --> 00:18:46,658
developed these materials
636
00:18:46,658 --> 00:18:49,061
that show quantum insulators,
637
00:18:49,061 --> 00:18:51,363
and they kindly provided that to us.
638
00:18:51,363 --> 00:18:53,065
So without NSF
639
00:18:53,065 --> 00:18:54,299
and then the collaboration
640
00:18:54,299 --> 00:18:55,501
with Doctor Samarth
641
00:18:55,501 --> 00:18:56,702
accessing these methods
642
00:18:56,702 --> 00:18:58,270
would not be possible for us.
643
00:18:58,303 --> 00:18:59,271
And on top of that,
644
00:18:59,271 --> 00:19:00,672
a couple of students on
645
00:19:00,672 --> 00:19:01,907
this project
646
00:19:01,907 --> 00:19:04,276
were supported by NSF.
647
00:19:04,543 --> 00:19:05,744
The idea
648
00:19:05,944 --> 00:19:07,713
behind this non
649
00:19:07,713 --> 00:19:09,715
Hermitian physics
650
00:19:09,715 --> 00:19:11,717
and exploring them in quantum,
651
00:19:11,717 --> 00:19:13,051
and also emerged
652
00:19:13,051 --> 00:19:14,853
from a support that we had
653
00:19:14,920 --> 00:19:16,421
from another
654
00:19:16,421 --> 00:19:18,190
center at Penn State,
655
00:19:18,557 --> 00:19:19,892
NSF supported center.
656
00:19:19,892 --> 00:19:22,060
It's a MRSEC center
657
00:19:22,060 --> 00:19:23,695
for nanoscale science.
658
00:19:23,695 --> 00:19:26,064
So we had a seed grant from that center.
659
00:19:26,064 --> 00:19:28,300
And that kind of a kick
660
00:19:28,300 --> 00:19:29,468
started the whole project.
661
00:19:29,468 --> 00:19:31,036
So I would say without NSF,
662
00:19:31,336 --> 00:19:33,438
this would not have been possible.
663
00:19:33,438 --> 00:19:35,741
Whatever we talked about so far,
664
00:19:35,841 --> 00:19:37,042
this is very,
665
00:19:37,109 --> 00:19:39,278
very crucial to have NSF support,
666
00:19:39,311 --> 00:19:40,345
especially supporting
667
00:19:40,345 --> 00:19:41,380
fundamental research,
668
00:19:41,380 --> 00:19:43,882
because you might not know
669
00:19:44,082 --> 00:19:45,617
what they might lead to,
670
00:19:45,717 --> 00:19:46,919
but who knows,
671
00:19:46,985 --> 00:19:48,220
ten years down the road,
672
00:19:48,253 --> 00:19:50,522
what we are doing right now might help.
673
00:19:50,556 --> 00:19:51,790
They take something tiny
674
00:19:51,790 --> 00:19:54,026
that we couldn't have detected before.
675
00:19:54,193 --> 00:19:56,595
So thinking about that feature impact,
676
00:19:56,595 --> 00:19:57,829
for my last question,
677
00:19:57,829 --> 00:19:59,264
I want to ask you,
678
00:19:59,264 --> 00:20:01,333
where are you excited to see
679
00:20:01,400 --> 00:20:02,401
quantum research,
680
00:20:02,401 --> 00:20:03,502
specifically in your lab,
681
00:20:03,502 --> 00:20:04,903
I suppose, and maybe broadly to
682
00:20:04,937 --> 00:20:06,772
if you want, where do you want to see it
683
00:20:06,772 --> 00:20:08,040
go in the next few years?
684
00:20:08,040 --> 00:20:09,107
So I would make this
685
00:20:09,107 --> 00:20:10,375
a very broad statement.
686
00:20:10,375 --> 00:20:12,144
I used to work a lot
687
00:20:12,177 --> 00:20:14,947
on making qubits resilient.
688
00:20:14,947 --> 00:20:15,881
I would call them.
689
00:20:15,881 --> 00:20:17,482
So this concept of fault
690
00:20:17,516 --> 00:20:19,618
tolerant quantum computing
691
00:20:19,618 --> 00:20:21,119
so that you don't
692
00:20:21,119 --> 00:20:22,454
have to worry about errors.
693
00:20:22,521 --> 00:20:24,122
And over the past several years,
694
00:20:24,122 --> 00:20:25,557
I would say we have made
695
00:20:25,557 --> 00:20:27,226
a lot of progress
696
00:20:27,259 --> 00:20:29,461
making quantum systems scalable so
697
00:20:29,494 --> 00:20:30,696
they’re like bigger.
698
00:20:30,829 --> 00:20:31,530
And
699
00:20:32,531 --> 00:20:33,999
what I'm really excited
700
00:20:33,999 --> 00:20:35,334
to see is hopefully
701
00:20:35,400 --> 00:20:36,635
we passed
702
00:20:36,635 --> 00:20:38,537
a bottleneck of fault tolerance.
703
00:20:38,537 --> 00:20:40,138
We get to a stage
704
00:20:40,138 --> 00:20:42,541
where qubits are resilient.
705
00:20:42,774 --> 00:20:45,110
We don't have to worry about errors,
706
00:20:45,110 --> 00:20:47,512
and that would enable us to actually
707
00:20:47,546 --> 00:20:48,880
see real impact,
708
00:20:48,914 --> 00:20:50,515
like quantum computers
709
00:20:50,515 --> 00:20:52,551
solving some of the fundamental problems
710
00:20:52,551 --> 00:20:53,952
that we have been dealing with.
711
00:20:53,952 --> 00:20:54,386
I don't know,
712
00:20:54,386 --> 00:20:56,021
maybe we find a cure for cancer.
713
00:20:56,021 --> 00:20:56,822
Who knows?
714
00:20:56,822 --> 00:20:58,690
I'm an optimist,
715
00:20:58,890 --> 00:21:01,493
so I'm not one of those people
716
00:21:01,493 --> 00:21:03,228
who think quantum is a hype.
717
00:21:03,262 --> 00:21:04,463
I believe
718
00:21:04,563 --> 00:21:06,198
we have made real progress
719
00:21:06,198 --> 00:21:08,233
and given more opportunities.
720
00:21:08,233 --> 00:21:09,434
I believe
721
00:21:09,501 --> 00:21:10,802
there is a future
722
00:21:10,802 --> 00:21:12,337
where quantum computing
723
00:21:12,337 --> 00:21:13,872
could shine in certain
724
00:21:13,872 --> 00:21:16,308
areas of our life.
725
00:21:16,675 --> 00:21:18,610
Special thanks to Morteza Kayyalha.
726
00:21:18,677 --> 00:21:19,978
For the Discovery Files, I'm
727
00:21:20,012 --> 00:21:20,779
Nate Pottker.
728
00:21:20,779 --> 00:21:21,313
Watch video
729
00:21:21,313 --> 00:21:22,681
versions of these conversations
730
00:21:22,681 --> 00:21:24,816
on our @NSFScience YouTube channel.
731
00:21:24,883 --> 00:21:25,617
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732
00:21:25,617 --> 00:21:26,818
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733
00:21:26,818 --> 00:21:28,253
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734
00:21:28,253 --> 00:21:29,154
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735
00:21:29,154 --> 00:21:30,722
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736
00:21:31,857 --> 00:21:32,758
Discover how the U.S.
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National Science Foundation
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is advancing research
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at NSF.gov.
