Hi, I'm Biswaroop


My name is Biswaroop Mukherjee. I’m a PhD student at MIT, advised by Martin Zwierlein. I’m working on imaging and simulating ultracold quantum gases. I did my bachelors at UC Berkeley, where I was advised by Holger Müller. Feel free to contact me at roop AT mit DOT edu. Here are some of my latest projects:

Condensate: GPU-accelerated superfluid dynamics
I use CUDA and OpenGL to render numerical solutions to a nonlinear Schrodinger equation on an NVIDIA GPU. With a Leap Motion sensor, you can manually interact with the simulated superfluid in real-time.
Quantum walks on real quantum hardware
Biswaroop Mukherjee, Carsten Robens, Maya Reese, Lamia Ateshian, Yiqi Ni, and Enrique Mendez. iQuHACK 2020

We demonstrate 1D and 2D quantum walks on IBM quantum processors. Made using Qiskit during the iQuISE hackathon at MIT.
Breadboard: An image metadata API
Our lab data consists of images and metadata generated by the experiment. I built an API to serve the data using Django REST framework and PostgreSQL.

Research Papers

Here are some papers I’ve worked on:

Crystallization of Bosonic Quantum Hall States
Biswaroop Mukherjee, Airlia Shaffer, Parth Patel, Zhenjie Yan, Cedric Wilson, Valentin Crépel, Richard Fletcher, and Martin Zwierlein.
On the arXiv, 2021.

We observe a surprising spontaneous crystallization in an unconfined gas of ultracold atoms. Interactions and a synthetic magnetic field are the only two ingredients required -- the same two ingredients that result in the fractional quantum Hall effect.
Geometric squeezing into the lowest Landau level
Richard Fletcher, Airlia Shaffer, Cedric Wilson, Parth Patel, Zhenjie Yan, Valentin Crépel, Biswaroop Mukherjee, and Martin Zwierlein.
Science, 2021.

We prepare a Landau gauge wavefunction in the lowest Landau level by rapidly rotating a Bose-Einstein condensate. This paves the way towards the measurement and control of more exotic quantum Hall states using neutral atoms.
Universal Sound Diffusion in a Strongly Interacting Fermi Gas
Parth Patel, Zhenjie Yan, Biswaroop Mukherjee, Richard Fletcher, Julian Struck, and Martin Zwierlein.
Science, 2020.

We probe the diffusivity of a fermionic superfluid by measuring the attenuation of sound waves. Our findings inform theories of fermion transport, with relevance for hydrodynamic flow of electrons, neutrons and quarks.
Spectral Response and Contact of the Unitary Fermi Gas
Biswaroop Mukherjee, Parth Patel, Zhenjie Yan, Richard Fletcher, Julian Struck, Martin Zwierlein.
Phys. Rev. Lett. 2019.

We follow the spectral response of the unitary Fermi gas from the Boltzmann regime through quantum degeneracy and across the superfluid transition. We observe a clear change in two-body correlations as the gas becomes a superfluid.
Boiling a unitary Fermi liquid
Zhenjie Yan, Parth Patel, Biswaroop Mukherjee, Richard Fletcher, Julian Struck, Martin Zwierlein.
Featured in Physics. Phys. Rev. Lett. 2019.

We study the thermal evolution of a highly spin-imbalanced, homogeneous Fermi gas with unitarity-limited interactions. We observe a transition from a Fermi liquid to a classical Boltzmann gas, through a quantum critical regime with no well-defined quasiparticles.
Homogeneous atomic Fermi gases
Biswaroop Mukherjee, Zhenjie Yan, Parth Patel, Zoran Hadzibabic, Tarik Yefsah, Julian Struck, Martin W Zwierlein.
Editors suggestion. Phys. Rev. Lett. 2017.

We report on the creation of homogeneous Fermi gases of ultracold atoms in a uniform potential. We observe the emergence of the Fermi surface in momentum space, and produce homogeneous superfluids that exhibit spatially uniform pair condensates.
Cascade of solitonic excitations in a superfluid Fermi gas.
Mark Ku, Biswaroop Mukherjee, Tarik Yefsah, Martin Zwierlein.
Phys. Rev. Lett. 2016.

Via tomographic imaging of a fermionic superfluid, we observe the snaking and decay of a planar dark soliton, into a vortex ring and a solitonic vortex. The observed evolution of the nodal surface represents dynamics beyond superfluid hydrodynamics, calling for a microscopic description of unitary fermionic superfluids out of equilibrium.
Motion of a solitonic vortex in the BEC-BCS crossover.
Mark Ku, Wenjie Ji, Biswaroop Mukherjee, Elmer Guardado-Sanchez, Lawrence Cheuk, Tarik Yefsah, Martin Zwierlein.
Phys. Rev. Lett. 2014.

We observe a long-lived solitary wave in a superfluid Fermi gas of Li 6 atoms after phase imprinting. Tomographic imaging reveals the excitation to be a solitonic vortex, oriented transverse to the long axis of the cigar-shaped atom cloud.
Sisyphus cooling of lithium.
Paul Hamilton, Geena Kim, Trinity Joshi, Biswaroop Mukherjee, Daniel Tiarks, Holger Müller.
Phys. Rev. A 2014.

We achieve laser cooling of lithium via a combination of Sisyphus cooling followed by adiabatic expansion. We reach temperatures as low as 40 μK, which corresponds to atomic velocities a factor of 2.6 above the limit imposed by a single-photon recoil. Our results suggest that optical molasses should be possible with all alkali-metal species.