Quantum feedback control of a superconducting qubit: Persistent Rabi oscillations

Abstract

The act of measurement bridges the quantum and classical worlds by projecting a superposition of possible states into a single, albeit probabilistic, outcome. The time-scale of this "instantaneous" process can be stretched using weak measurements so that it takes the form of a gradual random walk towards a final state. Remarkably, the interim measurement record is sufficient to continuously track and steer the quantum state using feedback. We monitor the dynamics of a resonantly driven quantum two-level system -- a superconducting quantum bit --using a near-noiseless parametric amplifier. The high-fidelity measurement output is used to actively stabilize the phase of Rabi oscillations, enabling them to persist indefinitely. This new functionality shows promise for fighting decoherence and defines a path for continuous quantum error correction.

Manuscript: 5 Pages and 3 figures ; Supplementary Information: 9 pages and 3 figures

References in corpus (6)

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• Optimality of qubit purification protocols in the presence of imperfections
• Nonlinear quantum input-output analysis using Volterra series
• Quantum Implemention of an LTI System with the minimal number of additional quantum noise inputs
• Real-time Information, Uncertainty and Quantum Feedback Control