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Applied Physics Profiles

The Applied Physics program would be nothing without our incredible students, alumni, faculty and staff. Get to know some of these talented individuals below and hear about their experience with the Applied Physics program.

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Jens Koch

Associate Professor

Jens Koch is the Director of Graduate Studies for the Applied Physics program at Northwestern University. He also is an associate professor of Physics and Astronomy.

Koch's group focuses on theoretical condensed matter physics, quantum optics, and quantum information. He is most widely known for his direct involvement in the development of the "transmon qubit." This simple but robust circuit is the most widely used superconducting qubit in the community today. In more recent years, his group has helped push toward a new generation of superconducting qubit with even better performance and intrinsic protection from common errors that otherwise affect these devices.

Koch took time to talk about his background, the development of a quantum computer, and what he thinks help differentiate Northwestern's Applied Physics program.

What type of physics does your group investigate, and what applications do you hope to impact?

My work is in a subfield of physics called quantum computation, and it follows the powerful idea that quantum mechanics may enable us to perform certain computational tasks dramatically faster than possible on any modern supercomputer today. Building such a quantum computer has turned out to be a grand challenge for the last three decades. It is a difficult task because phenomena in quantum mechanics can be quite fragile and tend to disappear once physical systems become “big”. For example, quantum phenomena in a single atom are well-established, but controlling quantum phenomena in a large set of atoms is an intricate challenge! Despite these difficulties, researchers have made enormous progress and are closer to realizing a quantum computer than ever before.

My own research is theoretical in nature and devoted to helping develop the next generation of hardware for a future quantum computer. I am particularly interested in so-called superconducting quantum bits: an architecture in which small circuits made of superconducting elements serve as the quantum analogs of bits. My group collaborates closely with several experimental groups fabricating and testing these superconducting qubits, and our work helps improve their performance – a crucial step in the pursuit of a fully functional quantum computer.

How is a quantum computer different from the computers we use every day?

It is a common misunderstanding that a quantum computer would just be a faster version of the computers we use today. That is not quite true. Our current understanding is that quantum computers are better at very specific tasks (Factoring integers into prime factors, searches in unsorted databases, and simulating quantum mechanical processes are examples where such a speedup is believed to occur.) Given the special-purpose character of these tasks, it is not clear that everybody will want to replace their computer with a quantum computer! Nonetheless, there is a tremendous amount of excitement about the prospect of quantum computation. For instance, quantum computers could efficiently simulate chemical reactions and interactions between complicated molecules, thus revolutionizing the development of new medications. Generally, I think we have barely begun to scratch the surface of the opportunities that new quantum technologies will be able to afford in the future.

How did you get interested in this field?

I jumped into the field as a postdoc and have been fascinated with it ever since. My PhD work was in a different subfield and did not involve a lot of collaboration with experimentalists. Starting my research on quantum computation, I quickly had to learn how to work together with experimental colleagues, and this is something that truly enriched my research perspective. Being able to contribute to the scientific progress in the ongoing worldwide quest for developing new technology based on quantum mechanics is very exciting and fulfilling to me.

What do you enjoy most about being affiliated with the Applied Physics program?

I very much enjoy interacting with the wonderful and diverse set of students in our program. Witnessing the growth of our students from their first steps in year one to the point where they successfully defend their PhD thesis is a remarkable thing, and I am proud of our alumni who are now out in the world, pursuing exciting careers in academia and industry.

What do you hope Applied Physics students who work with you learn from the experience?

I hope that the students who work with me develop into competent, independent researchers. That entails great care in research, the patience to check and double check one’s own results over and over again, and the skill to think carefully about how to best explain the results to colleagues and broader audiences.

What do you think differentiates Northwestern's Applied Physics program?

Northwestern’s Applied Physics program is a program that brings together faculty from a number of departments hosted by both the Weinberg College of Arts and Sciences and the McCormick School of Engineering. Incoming students have the opportunity to pair up with advisers from any of the participating departments, and we have successful examples of students who are co-advised by faculty from different departments. This underlines the flexibility and interdisciplinarity of the program, which makes it quite different from many Applied Physics departments elsewhere.

What would you say to a prospective student considering the Applied Physics program?

I would recommend the student carefully consider the breadth of research opportunities. Our program is young but flourishing, and we are seeing successful outcomes with our graduating students and alumni. Acceptance to Northwestern’s Applied Physics program opens the door to working with star faculty from a range of departments, to get an excellent interdisciplinary education, and to build an exciting career.

olvera168x210.jpgprofessor MONICA OLVERA DE LA CRUZ

Monica Olvera de la Cruz is the Lawyer Taylor Professor of Materials Science and Engineering, Chemistry and (by courtesy) Chemical and Biological Engineering, Physics and Astronomy at Northwestern University. She serves as the Director of the Center for Computation and Theory of Soft Materials and Co-Director of the Center for Bio-Inspired Energy Science.

Students who work with Olvera de la Cruz research the development of models to describe the self-assembly of heterogeneous molecules, as well as segregation and interface adsorption in multicomponent complex fluids.

In 2017, Olvera de la Cruz won the American Physical Society Polymer Physics Prize for her contributions to the theoretical understanding of polymers and the effects of electrostatic interactions on their structure.

She took time to talk about her experience with students in the program and what advice she would offer to prospective students.

How do you describe your research to someone with little to no scientific knowledge?

I try to understand systems that contain many molecules that have comparative effects that manifest themselves in different physical properties. I also like to be able to apply my knowledge to very down-to-earth problems that could have a significant impact on many people.

What do you hope students in your research group learn during their time in the Applied Physics program?

I want them to learn the basics of the techniques we use. They have to be able to understand the concepts of thermodynamics, statistical mechanics and kinetic theory. From there, I want them to be able to get the concepts and apply them to a mathematical equation. My hope is they will be able to solve specific problems where there are many forces — either numerically or by using computer simulations.

What do you enjoy most about working with students?

I enjoy watching as students learn to make connections. It’s fun to be able to explain a concept that seems to be complex, but then they are able to use that concept to develop solutions and draw connections between different things. To me, it is all about learning by doing. You can’t learn everything just by reading books. A carpenter won’t learn to master their craft without practicing. Particularly with applied physics, you can’t truly understand the physics until you learn to apply them.

What do you think helps differentiate the Applied Physics program?

Students in Applied Physics need to know a lot of physics, but they also have to be interested in using physics concepts that are accessible and relevant to the general public. Many of the concepts in particle physics, for example, are not very applied. The Applied Physics program is for a student who wants to understand methods that are accessible and tangible.

What advice would you give to a prospective student considering the Applied Physics program?

The Applied Physics program is able to leverage the power of Northwestern University and interesting disciplinary interactions. The program features a number of faculty from different fields. Students should be open to see the breadth of the program and prepared to take advantage of it by taking courses in different disciplines.

Annaliese Ehlen
Annaliese Ehlen

2nd year graduate student

Research Group: Olvera Group

What was it about the Applied Physics program that initially appealed to you?
The interdisciplinary nature of the program, flexibility in adviser selection, and the potential to work with other students who were also interested in the applied side of physics. I was working before this and wanted to be in a program where I could learn physics and apply it to questions that weren't necessarily strictly in the physics department.​

What was your background prior to entering the program?
I was a phys​ics major in undergrad (with a women's studies minor) and then worked for four years in renewable energy policy and grid integration modelling. I knew I wanted to continue working with simulation-based research, and so I came back to school to build a more fundamental understanding of how simulation can enhance our ability to probe different interesting systems.

How would you describe your experience in the program?
Getting started in courses again after four years was a little rough, but the applied physics cohort is really close and supportive​. It was really nice to come in with a group so eager to help each other. I also appreciated that we took a class in the materials science department early on; this helped me understand the work that my group does in a way that I could not have coming from a pure physics perspective.

What are the two or three most important things you've learned while in the program?
Lots of physics that I had forgotten over the years​! Also a lot about the importance of asking for help, even if it doesn't feel great at first.

How do you hope to apply what you learn in the program to your career after graduation?
I hope to continue in computational research in some form. So, I'm hoping to build research and computing skills while here.​

What would you say to someone considering the Applied Physics program?
It's young and still establishing itself as a program — and it's fun to watch it grow. Everyone is very nice and so (in my experience) it's easy to build a supportive community around you. The course requirements are more interdisciplinary and reduced compared with those in the physics program, so you can get to know other departments and (in theory) start focusing on research earlier. Come join us!

 Xinyuan You's pictureXinyuan You

4th year graduate student

Research Group: Koch Group

What appealed to you about the Applied Physics program?

There are many top physics-related research opportunities at Northwestern University that provide students with a physics background great opportunities to apply their knowledge. Within the Applied Physics program, we have a lot of flexibility in terms of choosing research areas, advisors and courses. For example, students can choose advisors from Physics and Astronomy, Biomedical Engineering, Chemistry, Earth and Planetary Sciences, Electrical Engineering and Computer Science, and Materials Science and Engineering. It is also very common for students in Applied Physics to have co-advisors — usually one in theory and one in experiment. This allows the student to study problems both from a theoretical and an experimental point of view, which is very helpful.

How would you describe your experience in the Applied Physics program?

Students in Applied Physics usually choose their advisors several months after the beginning of graduate school. This is very helpful for international students like me, since I get more chances to talk to the professors and the senior students before I make the final decision. There are fewer required courses in Applied Physics compared with other similar programs, which gives me much more time to focus on the research. I feel very excited in this program, not only because of the research I am working on, but also due to the chances to be exposed to so many interdisciplinary fields that will be very useful in the future.

What are two or three of the most important lessons you've learned during your time in the program?

Collaboration is crucial to a good researcher. There are collaborations between different fields, and collaborations between theory and experiment. I find it is really helpful to talk to people with expertise different than mine, either when I encounter some specific questions that relate to my own research, or when I am just interested in some general concepts that might be useful in the future. The Applied Physics program at Northwestern is exactly the place where a lot of collaborations happen every day.

What are your professional goals?

I plan to seek a postdoc position after graduate school. For the far future, I hope I can do research in the fields I am interested in, either in universities or tech companies.

How do you think the Applied Physics program will help you accomplish those goals?

The courses and research I did here provides me with the skills and knowledge to realize those goals. Moreover, the combination of collaboration and independence I have experienced here will also be very useful for me in the future.

What advice would you give to a prospective student considering the program?

If you are a student who has a physics background and is looking to apply it in the applied sciences, the Applied Physics program is a great option for you. People here are very nice, so please feel free to contact us for any information you need for the program.

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Junjing Deng

2016 Graduate
Research Group: Jacobsen, C. Group

What was it about the Applied Physics program that initially appealed to you?
The NU Applied Physics program was established in 2011 when I was applying for PhD programs in the U.S. This joint PhD program between the McCormick School of Engineering and Applied Science and the Weinberg college of Arts and Science was fresh to me. The program is also a strong research hub with faculty from different departments, such as the departments of Physics & Astronomy and Materials Science & Engineering. At that time, I felt excited that I could have the freedom and opportunities to work with distinguished faculty in the research fields I was interested in.

What was your background prior to entering the program?
I got a Master’s degree in condensed matter physics before joining this program. I already had some research experience during my Master’s degree study, and I wanted to try a new research area for my PhD. I wanted to broaden my horizons. I wanted to implement the laws of physics and utilize the skills and intellectual approaches for a real-world application.

How would you describe your experience in the program?
I would say it was a very enjoyable experience. I had a nice advisor who had a crucial influence on my research. The research that I worked on truly excited me, so I was passionate about it.

What are the two or three most important things you learned while in the program?
Independence: Most of my research was carried out at Argonne National Lab, where I needed to travel and set up experiments by myself. However, these activities made me more independent, and the skills and experience learned from the practice helped me get my current
job.

Communication: The students in this program choose advisors in different departments. Someone could feel isolated if he/she doesn’t communicate with other students. Therefore, good communication with other people in this program is very important. It lets you feel connected in the program. In addition, it also provides opportunities to learn what research other people are doing, and what kinds of techniques can be used in my own research.

How important were the faculty to your educational experience?
I think the most important person during the PhD study is the research supervisor because he/she is the person you interact and work with regularly for approximately five years. I felt very happy that I found an advisor (Prof. Chris Jacobsen) whose personality and advising style matched me very well. He always gave me strong support and provided helpful advice on how to proceed with my research. He has been a delight to work with. His humor, optimism, generosity and wisdom have influenced me a lot.

When did you graduate?
I graduated in the summer 2016. I feel honored to be the first graduating PhD of the program.

What is your job title and description?
I am an assistant physicist at the Advanced Photon Source (APS) at Argonne National Lab. In that role, I perform X-ray instrumentation and imaging technique development; collaborate with the APS facility users to develop scientific projects using these techniques; and support users’ experiments in the facility.

How does what you learned in the Applied Physics program relate to your day-to-day responsibilities today?
The main work of my PhD project was concerned with developing improved approaches to X-ray ptychography, a high-resolution coherent X-ray imaging method. As a local user of the APS, I frequently had access to the APS to develop this imaging technique. My years of experience and knowledge on beamline experiments and instrumentation during the Applied Physics program prepared me well for switching from a user of the APS to operating an APS beamline to host users.

What would you say to someone considering the Applied Physics program?
In many PhD programs, students are supposed to pick a supervisor before even starting. Due to the lack of information, such arrangements often do not work out. The Applied Physics program I enrolled in doesn’t have such a requirement. Actually, it gave us one quarter to explore different research areas before choosing a final research advisor. This program has faculty from a variety of departments who are working on different research, spanning from condensed matter physics to photonics and biophysics. I think this is one of the best aspects of this program since it provides a variety of research options and the opportunities to find out the right one for you.

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