Interfacing superconducting qubits with light

Optical photons propagate with ultra-low loss and do not interact easily, which makes them perfect information carriers both in quantum and classical applications. Logical operations and sensing on the other hand rely on nonlinearities and strong interactions, that are typically realized with GHz clock speed electrical circuits. The field of microwave photonics combines these two domains of the electromagnetic spectrum with a diverse set of applications ranging from radar and satellite communication, to radio-over-fiber and remote sensing. At the quantum level however, no equivalent technology exists. This is particularly problematic because quantum systems rely on analog information exchange in a low-noise environment. As a result, quantum microwave circuits - such as superconducting processors and seminconductor spin qubits - so far are restricted to operate inside an isolated space at millikelvin temperatures and without the benefits of quantum photonics and optical fibers, i.e. high bandwidth, high density, low-loss, multiplexed, low thermal conductivity and noise resilient control and communication at room temperature.

Building on our modular electro-optic platform - one of the lowest noise and highest efficiency microwave-optical interconnects to date [1, 2] - we have generated microwave-optical entanglement in the continuous variable domain [3], and demonstrated a circulator-free, all-optical single-shot readout of a superconducting qubit [4] where all required signal conditioning is implemented at room temperature.

In this talk I'll review aspects of these results and then focus on our team's progress and challenges towards entangling superconducting qubits with time-bin encoded telecom wavelength single photon states at room temperature.