Quantum filtering one bit at a time

TL;DR

This paper explores quantum state purification using single-bit measurement records and demonstrates effective purification and feedback control for one- and two-qubit systems.

Contribution

It introduces a method for quantum state purification and feedback control based on digitized one-bit measurement data, a novel approach in quantum measurement processing.

Findings

Efficient state purification is achievable with one-bit measurements.

Quantum feedback control can be implemented using discrete measurement sequences.

The approach is effective for small multi-qubit systems.

Abstract

In this paper we consider the purification of a quantum state using the information obtained from a continuous measurement record, where the classical measurement record is digitized to a single bit per measurement after the measurements have been made. Analysis indicates that efficient and reliable state purification is achievable for one- and two-qubit systems. We also consider quantum feedback control based on the discrete one-bit measurement sequences.