Efficient Wavelength Conversion in Silicon Microring CROWs (Project Report 1201308-Y2)

The main goal of this NSF-funded project [1201308 - Year 2] is to develop an integrated photonics device technology based on silicon photonics which can be used for compact and efficient nonlinear classical and quantum photonics applications. “Mixers” in the title reflects the use of nonlinear wave mixing, such as through four-wave mixing, which is the foundational optical process for wide-span wavelength conversion and entangled photon-pair generation in silicon photonics.

Continuous quantum light from a dark atom

Cycling processes are important in many areas of physics ranging from lasers to topological insulators, often offering surprising insights into dynamical and structural aspects of the respective system. Here we report on a quantum-nonlinear wave-mixing experiment where resonant lasers and an optical cavity define a closed cycle between several ground and excited states of a single atom. We show that, for strong atom–cavity coupling and steady-state driving, the entanglement between the atomic states and intracavity photon number suppresses the excited-state population via quantum interference, effectively reducing the cycle to the atomic ground states. The system dynamics then result from transitions within a harmonic ladder of entangled dark states, one for each cavity photon number, and a quantum Zeno blockade that generates antibunching in the photons emitted from the cavity. The reduced cycle suppresses unwanted optical pumping into atomic states outside the cycle, thereby enhancing the number of emitted photons.