Session G03: Few-body and many-body physics with interacting photons

Live

In this talk I will discuss ongoing efforts at UChicago to explore matter made of light. I will begin with a broad introduction to the challenges associated with making matter from photons, focusing specifically on (1) how to trap photons and imbue them with synthetic mass and charge; (2) how to induce photons to collide with one another; and (3) how to drive photons to order, by cooling or otherwise. I will then provide as examples two state-of-the-art photonic quantum matter platforms: microwave photons coupled to superconducting resonators and transmon qubits, and optical photons trapped in multimode optical cavities and made to interact through Rydberg-dressing. In each case I will describe a synthetic material created in that platform: a Mott insulator of microwave photons, stabilized by coupling to an engineered, non-Markovian reservoir, and a Laughlin molecule of optical photons prepared by scattering photons through the optical cavity. I will conclude with a teaser to a superconducting microwave Chern insulator coupled to a Transmon qubit, where we explore topological circuit QED. Building materials photon-by-photon provides us with a unique opportunity to learn both what all of the above words mean, and why they are important for quantum-materials science.   

Live

We study the effective interaction between photons that travel as slow polaritons in an atomic gas. When the polaritons are counter-propagating and comprise Rydberg states of opposite parity, the collision between them is dominated by a resonant dipolar exchange. Owing to the long range of the dipole-dipole interaction, blockade processes are forestalled and their deficiencies avoided. We show that the robust conditional phase shift associated with this collision can be employed for generating maximally-entangled cluster states of photons. To form odd-parity polaritons, we utilize a three-photon ladder transition to the Rydberg level. Under certain conditions, this ladder scheme supports conventional slow-light polaritons while offering additional advantages, such as access to stronger orbital transitions, full or partial Doppler-free arrangements, and flexibility in tailoring a desired nonlinear optical response. In particular, we demonstrate tailoring of this scheme for counteracting motional dephasing and for recovering the homogenous absorption cross-section of inhomogeneously-broadened media.   

Live

Long-range Rydberg interactions in combination with electromagnetically induced transparency(EIT) in cold atom ensembles provide a platform to study quantum optics and few-body physics of interacting photons, where the strength, sign, and shape of the interactions are widely controllable. Such control can be applied to both coherent and dissipative interactions, which provides the potential to generate novel few-photon states. We study experimental control of few body interactions in Rydberg interacting ensembles, demonstrate an efficient, pure and indistinguishable single-photon source, and use that source to observe two-photon quantum interference between photons generated from the atomic ensemble and a single atomic ion, located in different buildings and linked via optical fiber.   

Live

The physics of cooperative atoms/radiators in regular 2D arrays is dominated by two properties: first, a strongly frequency-selective reflectivity and second, the ability of confining polariton modes cleanly on the surface. This makes such a system highly sensitive to and controllable by light fields. Applications of these systems include quantum information, metrology, and nonlinear single-photon techniques.