Quantum estimation of detection efficiency with no-knowledge quantum feedback

TL;DR

This paper explores how no-knowledge measurement-based feedback control can optimize the estimation of detection efficiency in quantum systems, achieving higher precision and decoherence cancellation.

Contribution

It demonstrates that no-knowledge measurement is optimal for estimating detection efficiency and shows the advantages of feedback control in simultaneous parameter estimation.

Findings

Higher precision at low or high detection efficiencies

No-knowledge feedback cancels decoherence

Simultaneous estimation outperforms independent estimation

Abstract

We investigate that no-knowledge measurement-based feedback control is utilized to obtain the estimation precision of the detection efficiency. For the feedback operators that concern us, no-knowledge measurement is the optimal way to estimate the detection efficiency. We show that the higher precision can be achieved for the lower or larger detection efficiency. It is found that no-knowledge feedback can be used to cancel decoherence. No-knowledge feedback with a high detection efficiency can perform well in estimating frequency and detection efficiency parameters simultaneously. And simultaneous estimation is better than independent estimation given by the same probes.