Accelerated stabilization of coherent photon states

Abstract

Control and utilization of coherent states of microwave photons is a ubiquitous requirement for the present and near-future implementations of solid-state quantum computers. The rate at which the photon state responds to external driving is limited by the relaxation rate of the storage resonator, which poses a trade-off between fast control and long storage time. Here, we present a control scheme that is designed to drive an unknown photon state to a desired coherent state much faster than the resonator decay rate. Our method utilizes a tunable environment which acts on an ancillary qubit coupled to the resonator. By periodically resetting the qubit and tuning it into resonance with the resonator, possible photon loss and dephasing of the resonator mode are corrected without measurements or active feedback. In general, our method is suitable for accelerating the control of coherent states in high-fidelity resonators.

Qubit Measurement by Multichannel Driving

“…Inspired by our recent work [46] on quickly stabilizing resonator states by a qubit drive, we propose in this letter a qubit measurement protocol which is based on driving the qubit close to the frequency of the bosonic mode through a non-resonant channel. Owing to the dispersive coupling, the initial vacuum state of the resonator begins to rotate selectively on the qubit state about a point controlled by the strength and phase of the qubit drive.…”