Generation of Quantum States of Light with a Josephson Laser

Quantum states of light are a topic of considerable current interest, and may lead to use of continuous variables for quantum information processing, as well as to quantum-enhanced measurements. Ideally, one would like to be able to generate such states simply, and to have the states contain large numbers of photons. We have recently developed a device, the cavity-embedded Cooper pair transistor, that uses the ac Josephson effect to inject large numbers of microwave photons into a cavity. The photons induce stimulated emission of additional photons from the transistor, making the device a single-emitter Josephson laser. Our efforts are now focused on determining the quantum state of the photons in the cavity, and on studying the quantum dynamics of this strongly non-linear system. Our group collaborates closely with the group of Miles Blencowe on this project.