Maxwell Delorenzo, Louis Robson, Jasper Hersov
What drew you towards a career of researching physics?
I think my story is pretty straightforward. Having studied maths from a young age, and having taken up physics in high school, I just liked the way relatively simple mathematics could explain things we see around us, an aspect which still fascinates me today.
Then of course you went into the field of quantum phenomena- did anything in particular draw you to this field?
It was for me a natural progression. For my thesis work I worked on the hydrogen maser (effectively an extremely accurate clock). When I finished my PhD, I worked for Hans Dehmelt at the University of Washington where I first learnt about ion traps. Then I went to NIST in 1975- my first job was to make the caesium beam atomic clock work, but later my group leader at that time got us the funding to start a project making clocks out of ions. That work on the ion clock, which started in ’75, still goes on today. The field of atomic clocks had huge overlap with the experiments that were being done for quantum information, which made it really easy to jump into the game.
In the case of our group at in Boulder, Colorado, when the first big wave of interest hit for quantum information, a huge development at least on the experimental side was Shor’s algorithm. and some of our theorist colleagues managed to develop a schematic for the implementation of a quantum computer with trapped ions. Two theorists proposed a basic idea for how quantum computing could be done with ions and sent us a pre-print of their paper proposing the basic idea. Within a couple of months, we were able to demonstrate that basic elements of what they were proposing. So anyway, that was the start of it. The main takeaway is that fields of science have huge overlap (like clocks and quantum information) and you never know which direction you end up going in.
Of course, in 2012, you won the Nobel Prize –to what extent were you as a researcher working towards winning a Nobel Prize, or was it quite unexpected?
Well the Nobel Prize is somewhat of a dream for physicists, similar to the Academy Award for actors. I have been asked similar questions before, and I think it would be a big mistake to shape your career around trying to win a Nobel Prize because the chances of anybody winning one is pretty small. And in the end the true reward is just being able to do interesting and truly fascinating work. Another way I could put it is this: if I hadn’t won the Nobel Prize, I wouldn’t have felt that my career was any less successful. As I said, the real prize is the ability to consider interesting problems in the frontiers of physics.
What do you think of the main factors that currently limit the power of quantum computers and how these be overcome in the future? Can such devices be applied to every problem? Or is there is there an inherent limit to quantum computing?
On the last part of your question, I don’t think we’re going to replace classical computers. In fact, it takes a fairly fancy advanced computer to manage our quantum computers, including the smallest ones we have. There are certain tasks like doing simple arithmetic- I don’t think quantum computers are very efficient at that. But there are certain problems for which quantum computers can achieve exponential scaling of memory and efficiency of operations compared to classical computers. And a good example would be the factoring algorithm by Peter Shor, discovered in the mid-nineties. It was there that you could see the real advantage. And there are certainly other problems where quantum computers can provide exponentially greater efficiency.
Do you think that in the future they will be used largely as they are now, mainly to model quantum systems?
Well quantum computers even right now have a variety of potential applications- the factoring algorithm for example would be of immense use in RSA encryption and decryption. However, I’ve served on a committee with Peter Shor, and he’s said that even classical cryptographers are coming up with schemes that as far as he knows, the quantum computer can’t crack, meaning that such a window may be rapidly closing. So whilst cryptography is a significant potential field in which quantum computing can be used, given that governments and organisations can broadly adapt to its development its use there is unlikely to be valuable in the long term.
You were mentioning the idea of simulation, and many of us, myself included, feel that’s going be the real application, to be able to simulate another quantum system of interest. And so, I think you’re correct that that’s where the real long-term application is going to be.
Is it then worth all the investment that’s going into quantum computers,if you believe there’s going to be limited usage?
We’re at a very crude stage with the current simulations that we are capable of doing. They’re usually small enough algorithms that we can actually already run them on a classical computer. However, we as a field are gradually reaching the frontier where we can no longer simulate operations on our smaller quantum computers, even with a classical computer, although as a whole we have not yet solved anything ground-breaking. I would think that, we probably are getting close to the point where ‘quantum supremacy’ will become a realistic concept. What will really put things in firm ground is if someone can create a quantum algorithm that tells us something new or solves a problem that we couldn’t solve before. I don’t think it’s unreasonable at all, and it could be in the next decade that that such a breakthrough will happen. We’ll see.
Moving on to more general concepts– why do you think scientific discovery is so important in the modern world?
It brings us new possibilities. One example, which is still off in the distance currently, that some people raise concerning quantum computing is that useful simulations may uniquely be able to advance medical development and clinical trials. Let’s say we could simulate the dynamics and action of such-and-such molecule on your quantum computer rather than having to go in the lab and synthesize it physically- the costs and difficulty of research would massively be decreased. So overall, scientific discoveries have clear social consequences which make them incredibly useful for humanity.
In your opinion, is the purpose of physics to make discoveries that will have practical purposes in the future, or to make discoveries for the sake of discovering more about the universe?
I’d say both. I’ve certainly been motivated by both. It’s always nice to be part of developments which have resulted in actual beneficial practical applications- I’ve worked on clocks and obvious applications there include navigations and systems like GPS. All of that technology went in to give us this navigation system which the average person can use, which is really pretty fantastic from the point of view of a researcher.
What also has brought immeasurable enjoyment to me is the experience itself of scientific experiment and discovery and being able to navigate and solve problems that people like Schrodinger and Einstein used to think about. You are probably aware of such problems as the E. P. R. paradox. Being able to use our modern technology and discoveries to deeply investigate phenomena has always been for me strong motivating factor, especially when it comes to teaching and working with students. Overall, I would say it’s the reason why many get into the field in the first place.
What advice would you give to aspiring physicists?
Whether it’s physics or any other field, I don’t have any magic formula, but I think all individuals should want to find something they interested in. From that point, in order to be successful, you will have to work hard. But if you like the subject then in a way it really won’t be work. I’ve always felt that physics has been more of a hobby than work to me- what drew me in was this combination of mathematics and real physical systems.
The other thing I would say is that even if you feel that your interests may be shifting, I wouldn’t let a little hitch in your progress change your mind too much. Although it depends, I think in most cases it’s better to pursue what you find interesting, if you want to prioritise the long-term fulfilment of your career.