Maintaining Quantum Coherence in the Presence of Noise through State Monitoring

TL;DR

This paper demonstrates that real-time quantum state monitoring using unsharp measurements can maintain high fidelity even amidst classical noise, enabling effective quantum control beyond typical decoherence limits.

Contribution

It shows that unsharp POVM measurements enable sustained high-fidelity quantum state estimation despite classical noise, advancing quantum control techniques.

Findings

High-fidelity state monitoring persists indefinitely despite noise.

Unsharp measurements mitigate effects of classical dephasing and amplitude noise.

Quantum control remains effective beyond decoherence times.

Abstract

Unsharp POVM measurements allow the estimation and tracking of quantum wavefunctions in real-time with minimal disruption of the dynamics. Here we demonstrate that high fidelity state monitoring, and hence quantum control, is possible even in the presence of classical dephasing and amplitude noise, by simulating such measurements on a two-level system undergoing Rabi oscillations. Finite estimation fidelity is found to persist indefinitely long after the decoherence times set by the noise fields in the absence of measurement.