Chautaari: Quantum Physics evokes awe among the general public. How intimidating is it? How is it different from classical physics?
The striking departure from classical physics to quantum physics is that the latter is not intuitive. Whereas the law of mechanics and to a great extent that of classical electrodynamics conform to our common sense, the fundamental axioms of quantum mechanics do not. A few concepts such as light, which appears to be smooth, continuous stream, consists of discrete packets of energy (particle called photon) was a radical concept when it was proposed in the early 20th century. But this idea was crucial in explaining the photoelectric effect (important for the photovoltaic cells). Another fundamental concept is that of wave-particle duality, which says that an entity can behave like a wave or a particle depending on the experiment you perform on it. Yet another concept is the uncertainty principle, which says you cannot exactly measure the position and the momentum of a particle simultaneously. The more precisely you measure one, the more uncertain the other becomes. These are all counter-intuitive concepts, but all fundamental to quantum mechanics. Over the years, they have been shown to work very well, and they now form the backbone of molecular, atomic, sub-atomic, and indeed much of physics today. And because the concepts are counter-intuitive, it may appear intimidating. But if presented well, it is fascinating.
Chautaari: Where is the research in quantum physics now ? What are the things we recently found out? Are we on the verge of insightful discoveries?
Quantum physics provides a basic set of principles, which can then be applied to many different systems. For example, one can compute the properties of atoms and the interaction between light and atoms. One can also study the properties of solids using the principles of quantum physics. There is a general term we use for such studies called condensed matter physics. One can study the origin of properties of protons and neutrons, which is what nuclear physicists do. And then one can study the very basic constituents of matter such as electron, quarks and gluons (Quarks and gluons make up protons and neutrons). The study of the properties of electrons, quarks, gluons, and their interactions is called high energy particle physics. In this sense, the research in quantum physics spans a wide range. In condensed matter physics, for example, people are working on understanding the principles of high temperature superconductors, which will be tremendously useful if we can find a general solution. In quantum computation, people are trying to exploit “quantum bit” instead of classical binary bit. Nuclear physicists are trying to understand the origin of properties of protons (its spin, for example). In high energy particle physics, which is my field of expertise, we are trying to understand the most basic constituents of matter and how they interact with each other.
In the last 100 years scientists have understood a lot about the fundamental constituents of matter and their interaction. An active collaboration between theorists and experimentalists has consolidated our understanding into a framework that came to be called the Standard Model (SM) of Particle Physics. With the recent discovery of the Higgs boson by the ATLAS and CMS experiments at CERN’s Large Hadron Collider, the SM now has all the pieces in place for it to be a complete theory. However, it cannot be the final theory of Nature.
Several phenomena observed in nature are not explained by the SM. For example – Why is there such a large asymmetry between matter and anti-matter? What is the origin of neutrino mass? What is the nature of dark matter? Additionally, there are features of the SM that are not well-understood: How does the Higgs boson interact with itself? Is the recently discovered Higgs boson the only one of its kind, or are there more? These unanswered questions have led theorists to propose theoretical models, which address the shortcomings of the SM, and which consequently predict the existence of new particles. And these unanswered questions form the basis of my research interest. In particular, I focus on the measurement of the properties of the recently discovered Higgs boson and also look for evidence of additional Higgs bosons.
Now it is difficult to predict what we will find, what discoveries will be made. We can build our mathematical models and form our hypothesis about nature, but how it will reveal itself is up to nature. We may find additional Higgs boson, or we may not. Same with dark matter particles. 50 years passed between theoretical prediction and experimental discovery of the Higgs boson. 100 years for gravitational waves. So there is really no telling. But preparations anticipate discoveries, and some of the highly anticipated discoveries are super-symmetric particles, which will not only address the shortcomings of the SM, but also provide natural candidate for dark matter detection. When this will happen, we don’t know.
Chautaari: What is a typical day in a quantum physicist’s (your) life like?
I cannot speak for all quantum physicists, or even for all high energy physicists, but my schedule varies drastically depending on the projects I am working on and their deadlines. Sometimes for a block of 1-2 months, I am on shift in the control room. This means, for 8 hours, I am in front of a computer, making sure that the quality of the data we are recording is good, that all detector parts are working, or if they are not, noting down which ones are not etc. And that happens 24 hours a day, so my shift can be either between 7 am to 3 pm, or 3 pm to 11 pm, or from 11 pm to 7 am. At other times, I may be analyzing the data we have already recorded. Then the exact time is flexible, so I am only constrained by the meetings I have to attend. Otherwise, I work on my own schedule. I may get up around noon, have brunch and then go to work. Then I meet people, reply emails, attend meetings, do some relaxed work until about 5 or 6. Then I grab something to eat and go back to work. And between 6 pm and midnight, I do most of the work that require greater concentration.
Chautaari: Tell us about your Physics journey.
Since around middle school, I was fascinated by physics. I do not know the exact reasons. Perhaps it was because the geniuses we are told about were physicists – Galileo, Newton, Einstein. Perhaps it was because it seemed more fundamental, more basic than other sciences, although I am sure I didn’t think of it that way. In 9th grade, I learned from a friend that protons are not fundamental, that they are made up of something even smaller called quarks. I remember feeling highly disturbed. This destroyed the nice and complete picture I had of fundamental constituents of matter that they are all made up of atoms, which are further made of protons and neutrons forming the nucleus, and electrons that “revolve around” the nucleus like planets around the sun. The picture was not entirely complete – for example, what holds the positively charged protons together in a nucleus – but it seemed complete. But now these quarks! Are they then made up of something even smaller? Will it ever end? I followed up by reading a lot of science books meant for general public – A Brief History of Time, The Ascent of Science etc. – and I learned about the ideas that I found fascinating – quantum mechanics, black holes, relativity, elementary particles. By the time I finished SLC, I knew I’d opt for Physics for I.Sc. Which also meant it would give me the option to pursue engineering if I chose to be more practical and make a living (and perhaps it’d placate my family that I would not become a medical doctor, engineering is not a bad profession.). But then, during I.Sc. I realized, I didn’t want to be useful, so I applied for college in the U.S., to study physics, although at that point I put down computer science as my potential major on my I-20 (that seemed to me more visa-friendly.). And after college, I went to grad school, where I had several options to choose from – condensed matter physics, astrophysics, biophysics etc. But the issue of protons and quarks had somehow remained with me, so I chose high energy particle physics, which allows me to study the quarks and their interactions, to study the Higgs boson, and other truly fundamental particles. When I say fundamental, I mean particles that, as far as we know, are not composed of further smaller particles. This has been a very pleasant journey. So far.
Chautaari: Tell us about a time you made an exciting breakthrough — or any other highlight in your quantum physics journey.
In the current field of high energy particle physics, no single person or even single institute can solely claim a major scientific discovery. The results are work of thousands of scientists from hundreds of institutes for decades. But this global collaboration has resulted in what can only be called a real triumph of humanity, and I was fortunate to be part of that collaboration at the time of the discovery. The discovery I refer to is that of the Higgs boson. The particle was predicted back in the 60s and is a crucial element of the Standard Model of Particle Physics, but it had eluded scientists for almost 50 years. After years of research – the construction of the LHC, the design and construction of individual experiments around the LHC, years of simulated studies, actual data taking, and analysis of data – we finally found the long-sought Higgs boson. We had some hint already in 2011 and as we collected more data, it became more and more confirmed. As an insider, I knew of this of course, but to invite the media, to hold a press conference, and to announce the discovery in a public forum was really exciting! I knew this was monumental, that this’d go down in history as a milestone. Witnessing history-making was something. In the history of physics, there will now be before 4th July 2012 and after 4th July 2012.
Chautaari: Tell us about a time you had serious doubts about your own ability in this field. How did you overcome it?
I have serious doubts about my ability everyday. I try to overcome it by working harder.
Chautaari: If you were in the admissions committee, what qualities would you look into a prospective graduate candidate in quantum physics?
I have worked with several undergraduates and a few PhD students, so my thought on this is severely limited by my experience. That said, I’d like to work with students who are motivated and diligent. Good technical skills are necessary, but can be learned. Motivation, passion, enthusiasm, perseverance are something that have to come from within. Even if a student is technically excellent but lacks motivation or passion, then her/his career may not be fulfilling. And frankly it is no fun working with such a person. For thesis research – for any research – perseverance is very important.
As an admissions committee member, you don’t get to spend time with all the applicants to know them well, so the committee has to make a decision based on things like GRE scores, transcripts, letters of recommendation, prior research experience and other achievements, research interests of the applicant, availability of funds for such research etc. So if the transcripts, GRE, prior experience, letters all speak coherently of the candidate, and if there is funding in the applicant’s field of interest, then he/she stands a good chance of getting in.
Chautaari: How can prospective graduate students prepare themselves for pursuing graduate studies in Quantum Physics?
Do well in your undergraduate courses. When possible, get involved in research activities. It doesn’t have to be a grand project. It is not necessarily the glamor of the project that helps you, but the rigor with which you apply yourself, the process you learn, the techniques you develop and apply – even if they are small, they can define a research project. Learning to define a problem, to create strategies to solve it, assessing the necessary resources, defining and meeting deadlines are all important in a research career. So if you can get some of these as an undergrad, you already have a taste of it. This may excite you, or it may dissuade you from a career in research.
Learn programming and statistics. No matter which field you go into, it will be very useful.
Chautaari: How is the job scenario for graduates in quantum physics ?
A degree in physics trains you to think analytically, to build mathematical models, to do statistical analysis. These are all highly valued skills in the job market. Besides academia, the skills learned as part of a physics degree are very well compensated by hardware and software companies, finance institutions, big data analytics companies etc. If you keep an open mind about the job (not necessarily seeking a university job, for example), the global opportunities are great.
Chautaari: Can you recommend 5 universities that someone with an interest in your field should check out?
In my field, no single university is good enough to do the projects by itself. There are over 15000 staff – scientists, engineers, technicians etc. – working on the LHC experiments. Even on the single experiment I am working on, there are over 3000 scientists and engineers from about 200 institutes from over 40 countries. Each institute has played a significant role in either building the detector part (of which there are many), commissioning the detector underground, calibrating the detector, running simulation, taking data, analyzing data, and so many other aspects of a truly global experiment. So depending on the interest of the applicant, some universities may be stronger than others in that particular area, and this the applicant has to find for herself/himself. But I can offer a few general guidelines that may be of non-zero value.
- Study hard and do well in undergraduate courses. The transcript is an important part of the application.
- Do some soul searching and make a list of your top research priorities. Are you interested in experiment or theory? In high energy particle physics, or astroparticle physics, or nuclear physics? Even in high energy physics, are you interested in collider experiments like the LHC, or dark matter detection experiments, or neutrino experiments? Narrowing down your choices like this will help you make a shortlist of the universities that are working on these projects.
- Once you have a shortlist of universities, I suggest you contact the professors directly. They may not reply to emails. I suggest calling them. You have to find out if there is funding for this research. If you really want to do that research, the professor will hear the calling in your voice, your enthusiasm. This doesn’t guarantee that you will get in, but this may help during the application review.
- Prepare your application diligently. Have the referees write a letter that is consistent with the rest of the application, that is personal (not general), that describes your strength as reflected in your CV but also describes areas in which you should improve etc.
- Work on the research statement. Write it, edit it, re-write it, edit it … Have someone else read it and give feedback. Edit it. This is the time to truly shine, to show off what you have done so far, how it ties up with what you want to do in grad school, and perhaps later in life.
- Review the application material. Seek advice. Make sure there are no language problems. You have to put in the effort.
These are all things that most students know, but it doesn’t hurt to be reminded.
Chautaari: Can you recommend 3 resources for people looking to get into your field ?
Chautaari: Tell us about the role of mentorship in your professional life.
Mentorship is very important. There is just so much to learn that is not in the textbook. As a PhD student, it is very important to choose your supervisor carefully. The research interest has to match and also the work style and to some extent personalities. Some are lucky and find a perfect mentor – I was one of the fortunate ones. Even as a postdoc, you work very closely with senior professors – who may be from different institutes – from whom you continue to learn physics, but also about the direction of the field, the resources in the field etc. But one can – and I certainly do – learn from my juniors. When you are stuck on a problem, it is very helpful to discuss it with someone else. And I have received a lot of help from other postdocs, graduate and undergraduate students.
I have also been in the role of a mentor. I have had the opportunity to work with several summer students and worked very closely with a few graduate and undergraduate students. I enjoyed the experience a lot and will certainly continue to work with more students in the future.
Chautaari: What is the best career advice you have ever received?
Ask me again in 35 years.
The career advice you wished you received in your twenties.
Nobody forced me to do anything in my early twenties. I was in college, and I was taking courses that I found fun. Looking back I know computer science courses would have been more useful than postcolonial literature, but I had fun in that class, and even from today’s perspective I’d not trade. I tried experimental condensed matter physics research for one summer and theoretical electrodynamics research for one semester. I did those out of curiosity and that experience helped me make the decision in grad school to not pursue them. I think I was too arrogant to listen to anyone else. (This, I have been assured by my closest friends, has not changed.)
Chautaari: Final words of advice for someone who wants to pursue their interest in quantum physics?
I have had fun doing what I do. That doesn’t necessarily mean you will too. So don’t listen to me, listen to yourself.
Suyog Shrestha is a physicist on the ATLAS experiment at CERN’s Large Hadron Collider. His research focuses on the self-interaction measurement of the recently discovered Higgs boson and on searching for additional Higgs bosons.