My group is broadly interested in driven-dissipative quantum phenomena occurring in engineered quantum systems. Our research is at the intersection of condensed matter physics, quantum optics, and quantum information. While we are theorists, we work closely with a number of leading experimental groups around the world.
Effective temperature (possibly negative!) of incoherently tunneling Cooper pairs. Read the paper.
There is enormous interest in engineering topological photonic systems, where topological protection guarantees the existence of robust edge modes. Most works in this field amount to replicating a well-known fermionic single-particle Hamiltonian. We recently studied a class of systems where this correspondence fails. Here, topology is induced by coherent two-photon driving (i.e. parametric driving). While these systems have a Hamiltonian resembling that of a fermionic topological superconductor, the bosonic physics is completely different. In particular, the topologically-protected edge states can act as frequency-converting channels, and can even serve as quantum-limited amplifiers and squeezed light sources. It is even possible to construct bosonic systems that are reminiscent of the fermionic Kitaev-Majorana chain.
We show how two-photon (or parametric) driving can be used to enhance the basic light-matter interaction in a generic cavity QED system, where a two-level atom (or qubit) interacts with photons in a cavity. Driving thus enables a weakly interacting system to behave like a strongly interacting one, and even allows one to reach so-called "ultra-strong" coupling regimes. Applications include the efficient production of highly entangled Schrodinger-cat style states. The effects we predict could be realized in a number of experimental platforms, including with superconducting quantum circuits.