Interview with Professor Ryan Hadt

Interviewer: Wesley Huang


Favorite food: fish and broccoli

Favorite music artist: Bon Iver/ Drake

Favorite film director: Andrei Tarkovsky

Favorite molecule: copper tetrachloride 

What does your lab research?

We are a physical inorganic chemistry group that blends a wide range of spectroscopic techniques with theory and computation. We do this to study the fundamental electronic structures of transition metal ions. We are particularly interested in understanding the photochemical and photophysical properties of transition metal complexes that can be used in artificial photosynthesis or photoredox catalysis. This is a field of organic chemistry that utilizes light-absorbing transition metal compounds in excited states to drive chemical reactions that wouldn’t otherwise occur in ground states. We also develop new spectroscopic methods, one of which is ultrafast magnetic circular dichroism. This gives us the ability to study magnetism on excited states and to do it with femtosecond time resolution. Members of our group work on a range of projects, from fundamental problems about magnetism to more applied problems in photoredox catalysis. It all boils down to the fundamentals of transition metal ions and complexes and their applications.  

Why is it important to study this field? What are the possible real world applications?

We are interested in studying quantum information processing. In order to build a quantum computer, you essentially need to make the quantum version of a bit. In a classical computer, bits exist as the discrete states of zeros and ones. In order to physically realize a quantum computer, we need to develop qubits, or quantum bits. Transition metal complexes are potential quantum bits because they can form coherent superposition states within their magnetic spin sublevels. Currently, this is mostly done with microwave pulses in what’s called electron paramagnetic resonance spectrometer. We would like to do this all optically. This is a component of ultra-fast magnetic circular dichroism, using circular polarized pulses femtosecond pulses to create coherent superposition states within transition metal ions. So, if we can develop transition metal ions as qubits and understand the properties of the coherent superposition states, we can develop room temperature active qubits. To do this, we need to overcome qubit decoherence at room temperature, or the vibrational couplings between electron spin states and phonon modes. Understanding and making room temperature coherent quantum processing would be the next major advance in physical inorganic chemistry, which is why we are trying to get involved in that area. 

What is a problem that you solved during your most recent project?

Right now, we have a paper in review related to the mechanisms of spin phonon coupling in transition metal qubits. I briefly mentioned qubit decoherence before, specifically spin phonon coupling at room temperature. This recent paper lays the framework for theoretically and experimentally quantifying spin phonon coupling in transition metal containing molecules using ligand field theory. This gives inorganic chemists a road map for synthesizing new room temperature coherent materials.

What question or challenge were you setting out to address when you started this work?

We are really interested in the fundamentals of science, and that is what drives us.. Specifically, we want to understand how the decoherence mechanism operates. This fundamental question has major implications for things like quantum computing as well as for the development of photomagnetic materials and photocatalysts. The projects we undertake are all connected by the fundamentals. 

What aspect of being a researcher do you enjoy the most?

I love working with students and doing science. That is something I love doing everyday. I like to say that I never worked a day in my life because it’s just fun to collaborate and conduct research. It really is a dream job in that sense.  

What are some of the difficulties and successes in research?

The experiments that we perform can often be very technical. So, the most difficult thing is being able to measure what we want to measure at the end of the day. We are constantly striving to make the measurements more approachable and accessible. If you want detailed information content, getting the right instrumentation and doing proper alignments is important. 

How did you end up here, as a professor at Caltech? Any stories or inspirations that defined your career path (undergraduate experiences etc.)?

For me, it started in high school, where I had an excellent chemistry teacher. I wasn’t particularly into science or math, but he really inspired me and taught me to enjoy chemistry. Then, at each stage of my career, I had excellent mentors, including my graduate, PhD, and postdoc mentors. That is also something that is present here at Caltech. My senior colleagues are great role models and mentors. Having a good support system and having excellent mentors was really important for me. 

What are some of your views on undergraduate research experiences, and how does it shape future scientists?

Undergraduate research is extremely important. Undergraduate research played a major role in my decision to go to graduate school in chemistry. You can take classes all day, but to see the concepts and material in your courses manifest before your eyes in the laboratory is amazing. Whether you’re doing spectroscopy, synthesis, or computational chemistry, that’s the pinnacle of learning— the application of things you’ve learned in the classroom in the laboratory. I believe teaching and research go hand-in-hand in that taken together, the whole is greater than the sum of its parts.

What hobbies and interests do you have outside of science?

I love watching films and reading good fiction books. I also like to hit the gym and cycle, especially back at Stanford. It was so easy to hop on your bike and immediately be in a good cycling area. So, between the gym, reading, and movies, those are my main go-tos outside of the lab.  

Do you have any advice for Caltech students who want to get into research?

Don’t be bashful, and interact with people in the field of your interest. Talk to the people who are working on problems that you are interested in. Don’t be afraid to knock on someone’s door because a lot of people at Caltech will be receptive to those conservations. For me, when I did undergraduate research at the University of Minnesota Duluth, I remember having this book on my desk called Inorganic Electronic Structure and Spectroscopy. One of the editors was Edward Solomon from Stanford, whom I thought I would want to go work for. So, when my mentor took me to an American Chemical Society meeting in Chicago, we went to hunt this guy down. He introduced me, and I told him I wanted to go to Stanford to work for him. And that’s what happened. Undergraduate research opened so many doors for me coming from Duluth. It was a more undergrad focused place, so I didn’t know if I could make it to Stanford. But it turns out I was very well prepared, which again harkens back to having the right mentors. Just talking to people and networking goes a long way. Caltech is a unique place, and now that I’m here, I understand its allure. For the undergrad community, the student–faculty ratio is so low and all the faculty members are excited to chat about their research and potential opportunities for undergrads in the lab.

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