Noise-induced quantum coherence and persistent Rabi oscillations in a Josephson flux qubit

TL;DR

This paper theoretically shows that external classical noise can enhance quantum coherence and prolong Rabi oscillations in a superconducting flux qubit, demonstrating quantum stochastic resonance effects relevant for experimental quantum control.

Contribution

It introduces the concept that classical noise can induce quantum coherence and extend Rabi oscillations in flux qubits, a novel insight for quantum control techniques.

Findings

Noise increases off-diagonal density matrix elements.

Rabi oscillations persist longer with noise.

Effects demonstrate quantum stochastic resonance.

Abstract

We demonstrate theoretically the noise-stimulated enhancement of quantum coherence in a superconducting flux qubit. First, an external classical noise can increase the off-diagonal components of the qubit density matrix. Second, in the presence of noise, the Rabi oscillations survive for times significantly longer than the Rabi decay time in a noiseless system. These Rabi oscillations appear as a modulation of the forced response of the qubit to the ac driving field. These effects can be considered as a manifestation of quantum stochastic resonance and are relevant to experimental techniques, such as Rabi spectroscopy.