Professor Profile: Nate Harshman


Ean Marshall

Associate Physics Professor Nate Harshman is a theoretical physicist who focuses on particle physics and quantum information theory. He has published over 20 articles in scientific journals, has written for the Chicago Tribune, and has appeared on the Discovery Channel for a segment on science in pop culture.
Harshman sat down with AWOL writer Ean Marshall to talk about Google searches, Scrabble tournaments and quantum physics.

What first made you interested in theoretical physics?

I first fell in love with physics when I was five years old, and I saw the television program “The Cosmos” by Carl Sagan. It was a PBS documentary series, and it talked about the universe, relativity,  quantum mechanics and evolution—all sorts of science. But in particular, there was a section on twin paradoxes, which is a problem in modern physics. Even though I didn’t understand it, and actually I didn’t really understand it until I was in college, I was hooked in that when you do physics, it transforms the way you see the world. And what I really liked about physics was that based on these assumptions, since I do mathematical physics, you can say that this is a true answer. That’s not easy to do in most disciplines, where you can precisely define a problem and say the true and false of it.

What is entanglement in terms of quantum physics?

It’s a special way in which a whole system can contain more information than the parts. In classical mechanics, if you have a system, the different parts of that system may be correlated: if you measure widget A, you may learn about widget B, if you make measurements of the different parts of the same system. In quantum mechanics, those different parts of the system may share information that cannot be explained; there’s just too much information for classical physics to explain. Typically, we talk about this in the context of different atoms being entangled. This really means that if you have an atom on one side of a river and an atom on the other side of a river, and you’re making measurements on one atom, that atom has an effect on the atom on the other side of the river. The only way this works is that sometime in the past the atoms interacted with each other. So even though they are spatially separated, they share the same quantum state. Since they have the same quantum state, they have quantum correlations, or entanglement, and by measuring them with classical physics measurement, it seems very paradoxical.

Any biological or physical applications of this concept?

There’s a debate right now whether we need entanglement and quantum correlation to explain photosynthesis, because photosynthesis is a remarkably efficient process for converting light into chemical potential energy. Can we understand that energy without the use of quantum mechanics? In terms of physical applications, one of the reasons people study this is that they’re hoping to make a new generation of information processing devices. For example, people talk about quantum computers, which solve certain kinds of problems regular computers can’t do; they’re called hard problems. For example, the way we encrypt financial transactions over the Internet is using something called RSA encryption, which is based on the fact that it’s really hard to write a computer program to factor large numbers into primes. If you have a big enough number, like a number with hundred digits, the computer can’t figure out its prime factors. It just takes too long. So you can use a code system based on secret knowledge of prime numbers of these big things. If you had a quantum computer, which could exploit quantum coherence and quantum entanglement, then it could factor these numbers exponentially faster. People also want to build quantum computers because you can do a more precise simulation of quantum mechanics, and there are many quantum mechanical systems. Every single computer is built on transistors that were designed using quantum theories. So if we can model quantum mechanics better, we can make better materials.

How long do you think we have until this becomes a reality?

Quantum computers have been fifteen years in the future for the last fifteen years, so there has been progress, but progress hasn’t been as fast as people expected. Now there’s been recent progress on things like quantum sensors, where you use entanglement to make precise measurements. But the biggest quantum computers are still not big enough to really solve problems. The system has to be isolated from its environment, but you still have to control the interactions externally; then you want the computers to have a bunch more quantum systems, because the more atoms and electrons there are, the more efficient they will be. So you’re trying to make it big but isolated, yet still able to control it. There are about seven or eight competing systems, and the computer is not sure which one will solve the problem first.

Are Microsoft and Apple investing a little bit in these technologies?

Well, Apple has at least one quantum project. IBM has a history of funding this kind of stuff. There was recently an article by someone who said that if you had a quantum computer, you could speed Google’s search algorithm, so Google is certainly paying attention.

So the search engine would be even faster and more precise?

Yeah, you could do a Google search with better precision and at a much faster time.

What made you come to AU?

I’ve been here since 2003. Before this I was at Rice, where I had a temporary job. I applied to 50 jobs, and I got the one at AU. I’m very happy. DC is a great place to be. AU is a research university, but has a great liberal arts department and great professors.

Is there any way AU could improve the representation of the physics department?

Yeah, definitely. They’ve improved a lot the past few years. We have a new building, even though it’s the Sports Center Annex, it means new facilities for us, and that feels nice. I think what we need to do is get more students. We need more professors, and to get more students, we need to get more people, more applicants in the sciences and raise the profiles of sciences on AU’s campus.

I read on your personal profile about the Scrabble Tournaments. So what were some of the winning words?

Oh, well. It’s so hard to go back. I actually have records of them all.  I haven’t played in tournaments since 2001. I figured out that I could be a good physicist, a good husband, and a good Scrabble player, but I could only do two out of three, and so I chose husband and Scrabble player. So in this particular game, my words are not particularly good, not a bingo. A bingo is when you have a pile. Oh I had two, ‘sliming’ and ‘tilting,’ those aren’t very good. But they’re worth a lot of points. That word was worth 72. The key in Scrabble is to play bingos, you want to play all tiles at once, because you get a 50 point bonus. If you want to do well, you have to know all the two-letter words and three-letter words. There are about 96 two letter words and three hundred and some three letter words. You need to know all of the j, q, x, z and k words up to four letters. And then you need to know the bingo words. The way I would study it is, for example, if you have the six letters ‘tirade,’ and if you have anything from this sentence: ‘Angry talk by PMS hag,’ any letter from there and you add ‘tirade,’ and you have a seven-letter word. I didn’t make up that particular mnemonic device—that was not a very flattering one.

So there’s actually a mathematical component to this linguistic game.

Oh yeah, absolutely. It’s all about finding patterns. Here’s another one: ‘bizzess’ is an acceptable Scrabble word.