Document Type
Article
Publication Date
2-12-2024
Abstract
We propose and analyze a protocol for stabilizing a maximally entangled state of two noninteracting qubits using active state-dependent feedback from a continuous two-qubit half-parity measurement in coordination with a concurrent, noncommuting dynamical decoupling drive. We demonstrate that such a drive can be simultaneous with the measurement and feedback, while also playing a key part in the feedback protocol itself. We show that robust stabilization with near-unit fidelity can be achieved even in the presence of realistic nonidealities, such as time delay in the feedback loop, imperfect state-tracking, inefficient measurements, dephasing from 1/f-distributed qubit-frequency noise, and relaxation. We mitigate feedback-delay error by introducing a forward-state-estimation strategy in the feedback controller that tracks the effects of control signals already in transit. More generally, the steady state is globally attractive without the need for ancillas, regardless of the error state, in contrast to most known feedback and error-correction schemes.
Recommended Citation
Sacha Greenfield, Leigh Martin, Felix Motzoi, K. Birgitta Whaley, Justin Dressel, and Eli M. Levenson-Falk, Stabilizing two-qubit entanglement with dynamically decoupled active feedback. Phys. Rev. Applied 21, 024022 (2024). https://doi.org/10.1103/PhysRevApplied.21.024022
Peer Reviewed
1
Copyright
American Physical Society
Comments
This article was originally published in Physical Review Applied, volume 21, in 2024. https://doi.org/10.1103/PhysRevApplied.21.024022