Quantum feedback control of a solid-state qubit

TL;DR

This paper theoretically analyzes a quantum feedback loop for a solid-state qubit, demonstrating how feedback can synchronize oscillations and suppress dephasing based on coupling strengths and bandwidth considerations.

Contribution

It introduces a theoretical model for quantum feedback control in solid-state qubits, highlighting conditions for effective dephasing suppression and oscillation synchronization.

Findings

Feedback effectively suppresses dephasing when qubit-detector coupling exceeds environmental coupling.

Synchronization of quantum oscillations depends on feedback strength and bandwidth.

Optimal feedback conditions enhance coherence in solid-state qubits.

Abstract

We have studied theoretically the basic operation of a quantum feedback loop designed to maintain a desired phase of quantum coherent oscillations in a single solid-state qubit. The degree of oscillations synchronization with external harmonic signal is calculated as a function of feedback strength, taking into account available bandwidth and coupling to environment. The feedback can efficiently suppress the dephasing of oscillations if the qubit coupling to the detector is stronger than coupling to environment.