Extended Techniques for Feedback Control of A Single Qubit

TL;DR

This paper extends feedback control techniques with weak measurements to protect arbitrary quantum states, overcoming limitations of previous schemes that only worked for special states, and evaluates their performance numerically.

Contribution

It introduces a generalized feedback control scheme using different weak measurements for protecting any quantum state, broadening the applicability of prior methods.

Findings

Numerical calculation of optimal parameters for the scheme

Extended scheme effectively protects general quantum states

Comparison shows improved performance over earlier schemes

Abstract

The protection of quantum states is challenging for non-orthogonal states especially in the presence of noises. The recent research breakthrough shows that this difficulty can be overcome by feedback control with weak measurements. However, the state-protection schemes proposed recently work optimally only for special quantum states. In this paper, {by applying different weak measurements, we extend the idea of the state-protection scheme to protect general states.} We calculate numerically the optimal parameters and discuss the performance of the scheme. Comparison between this extended scheme and the earlier scheme is also presented.