2019/11/29 by Leigh S. Martin, K. Birgitta Whaley, Martin, Leigh S. +1 · 2 citations
Computer Science · Physics and Astronomy · #FOS: Physical sciences #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum Physics (quant-ph)
paper · pdf · doi:10.48550/arxiv.1912.00067
openalex publication_date 2019/11/29 · openalex created_date 2019/12/05 · openalex updated_date 2026/07/28
Measurement-based heralded entanglement schemes have served as the primary link between physically separated qubits in most quantum information platforms. However, the impossibility of performing a deterministic Bell measurement with linear optics bounds the success rate of the standard protocols to at most 50%, which means that the entanglement of the unheralded state is zero. Here we show that the ability to perform feedback during the measurement process enables unit success probability in a single shot. Our primary feedback protocol, based on photon counting retains the same robustness as the standard Barrett-Kok scheme, while doubling the success probability even in the presence of loss. In superconducting circuits, for which homodyne detectors are more readily available than photon counters, we give another protocol that can deterministically entangle remote qubits given existing parameters. In constructing the latter protocol, we derive a general expression for locally optimal control that applies to any continuous, measurement-based feedback problem.