Rapid Cavity-Based Mid-Circuit Measurement and Feedforward in a Neutral Atom Array

Abstract:Measuring part of a quantum system in the midst of its evolution and acting on the result in real time is essential for numerous quantum information protocols. Neutral-atom arrays are a leading platform for quantum information processing, but their mid-circuit measurement-and-feedforward cycle times have remained slow, typically exceeding 1 ms. Here we demonstrate fast mid-circuit measurement and real-time feedforward in an array of atomic qubits coupled to a high-finesse optical cavity. Local light shifts tune individual data qubits out of resonance with the cavity, shielding their coherence, while a near-resonant probe drives a selected qubit whose emission is collected with Purcell enhancement. Mid-circuit measurements of four qubits with sub percent infidelity reduce the coherence of a fifth unmeasured data qubit by less than 2%. We implement real-time feedforward to correct measurement-induced phase shifts and to realize an adaptive circuit for optimal quantum state discrimination and conditional state preparation. Our approach reduces the measurement-and-feedforward cycle time to below 100 $\mu$s and establishes optical cavities as a route to fast control of neutral-atom quantum systems.

Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph)

arXiv:2606.24869 [quant-ph]

(or arXiv:2606.24869v2 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2606.24869 Focus to learn more arXiv-issued DOI via DataCite

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