I do theoretical research at the intersection between quantum optics, atomic physics, open quantum systems, and many-body physics. In particular, my research focuses on emergent phenomena that arises from collective atomic interactions.
Physics of correlated dissipation
Dissipation is a pervasive problem in many areas of physics. In quantum optics, the efforts directed towards engineering strong interactions between atoms and photons are typically thwarted by loss. The conventional strategy when dealing with dissipation is to increase the coupling between the atoms and the photonic mode of interest (that of a cavity or a waveguide), relative to the emission rate into “bad modes” (free space). In this picture, dissipation is considered to be a single-atom effect. However, if atoms are close enough to each other, photon emission becomes collective, as there can be interference. In particular, this interference can be destructive, and thus the atoms become subradiant. Below, you can find an image with the numerical calculation of the emitted field generated by the most subradiant collective mode (eigenstate) of a chain of 50 atoms in free space.
Recently, I have been exploring how these interactions through free space, which are typically neglected, can exponentially improve the fidelity of quantum memories. Moreover, correlated dissipation actually constitutes a rich many-body physics problem, with implications that branch out from quantum information science to quantum non-linear optics. If you want to know more about this subject, please check out our most recent work: PRX 7, 031024 (2017).
Quantum optics in unconventional baths
Photon-mediated interactions can be modified by placing atoms in different dielectric environments. In particular, photonic crystals – periodically modulated dielectric structures – display a bandgap in which light cannot propagate. This switches off dissipation through the photonic guided mode, making the interaction between atoms purely coherent (if we neglect dissipation into free space). This makes photonic crystals suitable platforms for quantum simulation, as well as fascinating atom-light interfaces. The group of Prof. Kimble is a pioneer of placing atoms near these structures. You can see the most recent experimental result here PNAS 113, 10507 (2016). Our theory work describing how to understand atom-atom interactions in the presence of complex dielectrics, using the electromagnetic Green’s function, is here: PRA 95, 033818 (2017).