Stabilizing Rabi Oscillation of a Charge Qubit via Atomic Clock Technique

TL;DR

This paper introduces a hybrid superconducting circuit-atom system that employs atomic clock techniques to significantly stabilize and extend the coherence of Rabi oscillations in a charge qubit.

Contribution

It presents a novel method combining feedback control and atomic Ramsey measurements to suppress noise and enhance coherence in superconducting charge qubits.

Findings

Longer relaxation times for Rabi oscillations achieved

Noise in the superconducting circuit effectively suppressed

Enhanced stability and coherence time of charge qubit oscillations

Abstract

We propose a superconducting circuit-atom hybrid, where the Rabi oscillation of single excess Cooper pair in the island is stabilized via the common atomic-clock technique. The noise in the superconducting circuit is mapped onto the voltage source which biases the Cooper-pair box via an inductor and a gate capacitor. The fast fluctuations of the gate charge are significantly suppressed by an inductor-capacitor resonator, leading to a long-relaxation-time Rabi oscillation. More importantly, the residual low-frequency fluctuations are further reduced by using the general feedback-control method, in which the voltage bias is stabilized via continuously measuring the dc-Stark-shift-induced atomic Ramsey signal. The stability and coherence time of the resulting charge-qubit Rabi oscillation are both enhanced. The principal structure of this Cooper-pair-box oscillator is studied in detail.