August 21, 2023
The fall semester starts later this morning, so now is as good a time as ever to write some brief thoughts on the courses I took at ETH Zürich in the spring. I took two German courses and almost five courses from the Master's in Quantum Engineering course catalog.
Taking this class was among the best decisions I made while on exchange. This was a fantastic way to spend my first two weeks in Zürich, as it jumpstarted my Deutsch learning at a clip of six hours per day, in a highly controlled, friendly environment. The instructor and teaching assistant, Margaryta, were both incredibly willing to answer questions I had about things outside of the curriculum, which only increased my curiosity and interest.
The class featured a field trip to the farmer's market as well as a scavenger hunt around the downtown and oldtown. Both were great opportunities to practice speaking Deutsch with Zürchers and get to know the city.
Throughout the semester I tried to speak Deutsch whenever possible (ie, in shops, in trains, at restaurants, on ski lifts with strangers, etc.). This was facilitated by my general lack of embarrassment. Making an active effort to speak was very helpful for improving my vocabulary, confidence, and general proficiency to express myself without having to search for each word. (This is probably a trivial observation, but I'm writing it anyway.)
Also an excellent class. At times it was challenging to stay focused since it was only ninety minutes per week and there were so many other competing interests for my attention, such as exploring Zurich, research, physics courses, European travel, etc. But I realized how much I liked language learning, so I bore down and caught up by the end of the semester.
A few of my roommates spoke Deutsch and were excellent conversation partners, and one in particular enjoyed answering all my grammar and usage questions. Orchestra rehearsals were conducted entirely in Deutsch, so that served as an additional several hours per week of immersion. At some point, I bought a pocket-sized Deutsch/English dictionary, which I consulted from time to time.
For language classes, I think the two-week intensive course format is much better than meeting once a week, because the learning becomes truly immersive (regardless of whether the class is fully taught in the language). But obviously there are some limitations with respect to scheduling an intensive course during the semester. I guess living in Zürich was a semester-long immersion either way.
As long as I regularly talk to myself in Deutsch and continue to think about the grammar, I should be able to keep my skills sharp. I don't have space next semester to take Deutsch, but if I end up at ETH in the future I'll take all the classes I can. In the meantime, I'll continue to keep the display language on my electronic devices set to Deutsch.
This was a fascinating class, covering a variety of interesting methods to solve quantum physics problems with a computer. Lots of math that I learned in fall 2022 in Numerical Linear Algebra came in handy. This class was the most different from the other physics classes, and I thought it was unique to round out my quantum information immersion with a course on other interesting topics in quantum mechanics.
One topic that I really enjoyed learning about was matrix product states. In Quantum Information Science II, which I took at UT in spring 2022, we briefly mentioned matrix product states, focusing mostly on their implications for measurement-based quantum computing and classical simulability. In this class, we covered matrix product states and operators for several lectures. It turns out that MPS-based methods such as DMRG (density matrix renormalization group) are an effective computational approach to finding ground states for certain types of physical systems. I felt like these lectures did the topic far more justice in terms of approaching it as an interesting and useful physics concept and not just something of auxiliary importance to demonstrate a complexity result.
The class also covered Monte Carlo methods for solving quantum spin and particle systems, and I thought the path-integral formulation of the partition function was particularly clever. We also covered variational Monte Carlo and discussed several classes of candidate variational wave functions.
The professor and I were both travelling in June, so I scheduled the oral exam for the first week of June, right after classes finished. This was my first ever oral exam, and I didn't really know what to expect. During the exam, I felt a bit unprepared and unconfident, especially when I could tell that certain questions were coming directly from early parts of the lecture script but couldn't remember the answer.
After the exam, I asked the professor for help on how to approach my remaining exams, and he answered with a lot of tips from his own experience as a student. So two silver linings from this exam were that it enabled me to figure out my remaining exams, and I had fortuitously chosen for this course to convey to UT as pass/fail so this specific exam wasn't that big of a deal.
This was also a great class. We opened with open quantum systems, talked about trapping, investigated ion structures, motivated motional modes, covered coupling and cooling, touched on two-qubit gates, moved to metrology, and concluded with computing. I felt like I ended the semester with a good understanding of the basics of the field, and I'd be interested to explore further through a research project.
This was my second exam, and I took it a week after the first exam. What I learned about oral exams the previous week certainly paid off, and I felt far more confident.
I wasn't sure whether this course would be redundant given that I had taken a quantum information science course I took at UT, but I'm incredibly thankful I took it. Although there was a bit of overlap at the beginning, this course ventured more towards theoretical physics topics and less towards theoretical computer science and complexity theory. My two favorite topics were quantum operations and stabilizer codes. Through this course, I gained much more of an appreciation for theoretical quantum information as a field, largely because it was taught by a physicist for a physics-minded audience.
I was able to prepone the exam and convert it to an oral exam. This exam was a couple hours after the trapped ion exam, and all the questions came from the second half of the course. The exam went well, and afterwards, I talked with the professor about my interest in the field and asked about the admissions process for ETH's master's programs.
This course was a survey of different hardware platforms for quantum information processing, with a little more time spent on the instructors' research area of superconducting circuits and active. Of course, "survey" is a misleading descriptor, and I was pleased by how much content we covered thoroughly.
The general structure of the first half of the course was walking through DiVincenzo's criteria for each platform. At times there was overlap with other courses I was taking (quantum dots and trapped ions), but the broader perspective of this course nicely complemented the specific implementation details of the other two. The second half of the course covered how to implement a two-qubit gate on various platforms, state and process tomography, qubit benchmarking, and implementations of quantum error correction (including the group's recent surface code publication).
This was formally my first course in quantum hardware, and concepts I've heard from the lab at UT began to click as the semester progressed. Optional problem sets provided ample opportunities to work through all sorts of interesting derivations, and I left with a much better understanding of research going on within the experimental side of quantum information processing.
I was also able to prepone this exam and convert it to an oral exam. The exam was administered by Dr Besse, with Prof Wallraff writing the protocol. This was my final exam and I felt like I had figured out how to take an oral exam by this point, so this one went very smoothly. Afterwards, Prof Wallraff asked me some questions about quantum engineering at UT Austin, and I expressed my interest in returning for the Master's in Quantum Engineering.
I also enjoyed this course, or at least what I got from it.
Unfortunately, I experienced a catastrophic failure in the class. The class met Wednesday afternoons at the same time as group meeting for the research group in which I worked. Compared to the US, where classes customarily meet twice a week, the physics classes at ETH met once a week, making it much easier to fall behind.
After missing one lecture, I decided to skip the next week so I could catch up with the one I missed. Unfortunately, this kept happening and I ended the semester several lectures behind. I would have tried to catch up during the exam study period, but I had scheduled the oral exam for early July, right after vacationing with my family and not thinking about physics. There were also some lingering problems with credit transfer back to UT, so I chose to deregister from the exam instead.
However, I thought quantum dots were quite interesting and would like to conduct research on them in the future.
One big difference worth mentioning is the grading and exam styles. At UT, there tend to be two to three exams per semester in advanced electrical engineering and physics classes. Exams tend to consist of several multi-part problem-set-style problems, with most of the points awarded for applying formulas and concepts learned in the course to solve a new, unfamiliar problem. In contrast, my grade for each class I took at ETH was entirely determined by a twenty- or thirty-minute oral exam, and the questions asked were closer to the lecture material than what I'm used to at UT. Having to adapt to the new format was a bit of a struggle at first, as I discussed above. However, I like the idea of proving to the professor that you understand the content.
It's also neat that the exam difficulty of an oral exam can be dynamically adjusted depending on how things are going. If the student quickly answers all of the easy questions, it would be a fun challenge to approach a harder, more abstract problem. Whereas if the student is having a hard time, then the professor can try to walk the student to the answer with a series of guided questions. However, I've been told that not all professors will do this and some will instead stare at you as you struggle through a question, so perhaps this last point is debatable.
When I was writing personal statements for why I wanted to come to ETH Zürich, I wrote that "a semester in Zurich would be incredibly valuable as a means of exposure to different research areas and topics that I ordinarily don’t have access to at UT." This semester surpassed all expectations: in the lab, I learned about quantum acoustics; in courses, I learned about quantum information processing with trapped ions and quantum dots, among other platforms; and I had access to an entire peer group and research community of quantum engineers. I was also finally able to learn about quantum information with an emphasis on what physicists care about. It's a great sign that I'm conflicted with which course to label as most interesting. The best way to summarize the technical side of the semester is that it solidified and strengthened my desired to continue studying quantum engineering.