Maintaining coherent oscillations in a solid-state qubit via continuous quantum feedback control
Rusko Ruskov, Qin Zhang, Alexander N. Korotkov
We discuss the operation of the one-qubit quantum feedback loop, which may be used for initialization of a qubit in a solid-state quantum computer. The continuous monitoring of a quantum state, which makes the feedback possible, is done by means of a weak continuous measurement and processing of the obtained information via quantum Bayesian equations. The properly designed quantum feedback loop can keep the desired phase of a single-qubit quantum coherent oscillations for infinitely long time, even in presence of a dephasing environment. Various nonidealities reduce the fidelity of the feedback synchronization. We report our study of the effects of finite available bandwidth and time delay on the one-qubit quantum feedback performance, and also discuss the effect of environment-induced dephasing.
Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Aug 24, 2004•3 citations