About me

Hi, I’m Kyle.

I recently completed a PhD in experimental quantum physics at JILA, where I studied the interactions between molecules at ultralow temperatures (< a billionth of room temperature). My Google Scholar and the research section below have more details about my research.

Now, I’m looking to pivot into software engineering. I’m especially interested in systems programming, compilers, and programming languages (especially Rust, C++, and functional languages like ML).

Some of my projects

  • Pomelo, a (very, very incomplete) compiler for Standard ML written in Rust. Learning Rust has made me really appreciate static types and type inference, so I wanted to learn more about how that’s implemented through this project. So far, I’ve made a basic lexer and parser for Core ML (no modules), and lowering to a tree-based IR. Hindley-Milner type inference is up next!

  • This website. I made it “from scratch” (i.e., not using a static site generator but still leaning heavily on the existing Rust ecosystem). In the process of figuring out how to host it, I got to learn a little about AWS, Docker, SSL, and NGINX. Check out my blog posts (part 1 and part 2) on building the site.

  • Small open source contributions to rustc and cargo. I haven’t done anything too complicated, but it’s been a great way to learn more about using tools like git more effectively and navigating larger codebases. And it’s crazy to think that my work is now a tiny part of these amazing pieces of software!

Outside of work, I’m also passionate about music (jazz piano).

PhD research

In grad school, I studied ultracold molecules in Jun Ye’s group. We used lasers to cool two different kinds of atoms (rubidium (Rb) and potassium (K)) from room temperature down to a few hundred nanokelvin. Once the atoms were cold, we could carefully bond them together into molecules (KRb) using a combination of magnetic fields and lasers.


Photograph of the experiment - a lot of optics and cables!
Here's a photograph of one corner of the experiment, taken about 5 years ago.

Ultracold gases of molecules have great potential as a platform for quantum science. At such low temperatures, the strong and tunable interactions between molecules can be used to generate highly quantum-entangled states. These exotic states, already fascinating in their own right, could further serve as a resource for quantum-enhanced sensors or shed light on questions in condensed matter physics (relevant to the design of new materials).

There’s a catch though: molecules don’t like to hang out together at ultralow temperatures. Unlike atoms, which happily collide off each other as they bounce around in our traps, molecules tend to get stuck together. More precisely, when our molecules get close to each other, they can undergo a chemical reaction (2KRb → K2Rb2) that releases enough energy to eject the products from our trap, leading to substantial loss of molecules over time. This problem turned out to be quite a general one, affecting many similar experiments around the world.

During my PhD, our team learned how to harness the molecular interactions to simultaneously suppress the “bad” lossy interactions while enhancing “good” interactions. A key technical factor was our ability to apply large, precisely-controlled electric fields to the molecules, which allowed us to fine-tune their quantum states. This capability, when combined with techniques like confining the molecules into two-dimensional layers, allowed us to control the molecular interactions to a new degree. Together with complementary approaches from other groups in the ultracold molecule community, these advances should open the door to new frontiers of quantum science with molecules.

Artist's rendering of molecules in our experiment confined to a stack of two-dimensional layers.
Illustration of molecules confined to two-dimensional layers. The molecules are trapped in the center of an in-vacuum electrode assembly, which allows us to apply large electric fields. (Artist: Steven Burrows (JILA)).

Publications

PhD thesis: Tunable dipolar interactions and collisional shielding in a quantum gas of polar molecules (2022)

Graduate work (JILA and University of Colorado Boulder):

  1. Tunable itinerant spin dynamics with polar molecules. J.-R. Li, KM, C. Miller, A. N. Carroll, W. G. Tobias, J. S. Higgins, J. Ye. Nature 614, 70–74 (2023).
  2. Reactions between layer-resolved molecules mediated by dipolar spin exchange. W. G. Tobias, KM, J.-R. Li, C. Miller, A. N. Carroll, T. Bilitewski, A. M. Rey, J. Ye. Science 375, 1299–1303 (2022).
  3. Tuning of dipolar interactions and evaporative cooling in a three-dimensional molecular quantum gas. J.-R. Li, W. G. Tobias, KM, C. Miller, G. Valtolina, L. De Marco, R. R. W. Wang, L. Lassablière, G. Quéméner, J. L. Bohn, J. Ye. Nature Physics 17, 1144–1148 (2021).
  4. Dynamical Generation of Spin Squeezing in Ultracold Dipolar Molecules. T. Bilitewski, L. De Marco, J.-R. Li, KM, W. G. Tobias, G. Valtolina, J. Ye, A. M. Rey. Physical Review Letters 124, 113401 (2021).
  5. Resonant collisional shielding of reactive molecules using electric fields. KM, L. De Marco, J.-R. Li, W. G. Tobias, G. Valtolina, G. Quéméner, J. Ye. Science 370, 1324–1327 (2020).
  6. Dipolar evaporation of reactive molecules to below the Fermi temperature. G. Valtolina, KM, W. G. Tobias, J. R. Li, L. De Marco, J. Ye. Nature 588, 239–243 (2020).
  7. Quantum many-body physics with ultracold polar molecules: Nanostructured potential barriers and interactions. A. Kruckenhauser, L. M. Sieberer, L. De Marco, J.-R. Li, KM, W. G. Tobias, G. Valtolina, J. Ye, A. M. Rey, M. A. Baranov, P. Zoller. Physical Review A 102, 023320.
  8. Thermalization and Sub-Poissonian Density Fluctuations in a Degenerate Molecular Fermi Gas. W. G. Tobias*, KM*, G. Valtolina, L. De Marco, J.-R. Li, J. Ye. Physical Review Letters 124, 033401 (2020).
  9. A degenerate Fermi gas of polar molecules. L. De Marco, G. Valtolina, KM, W. G. Tobias, J. P. Covey, J. Ye. Science 363, 853–856 (2019)

Undergraduate research (Harvard):

  1. Sisyphus laser cooling of a polyatomic molecule. I. Kozyryev, L. Baum, KM, B. L. Augenbraun, L. Anderegg, A. P. Sedlack, J. M. Doyle. Physical Review Letters 118, 173201 (2017).
  2. Proposal for laser cooling of complex polyatomic molecules. I. Kozyryev, L. Baum, KM, J. M. Doyle. ChemPhysChem 17, 3641–3648 (2016).
  3. Radiation pressure force from optical cycling on a polyatomic molecule. I Kozyryev, L. Baum, KM, B. Hemmerling, J. M. Doyle. Journal of Physics B: Atomic, Molecular, and Optical Physics 49, 134002 (2016).
  4. Collisional relaxation of vibration states of SrOH with He at 2 K. I Kozyryev, L. Baum, KM, P. Olson, B. Hemmerling, J. M. Doyle. New Journal of Physics 17, 045003 (2015).