Enhancing quantum memory lifetime with measurement-free local error correction and reinforcement learning

Journal Article · 13 January 2025 · Physical Review A

DOI: https://doi.org/10.1103/physreva.111.012419 · OSTI ID:2499721

Park, Mincheol  ^[1]; Maskara, Nishad  ^[2]; Kalinowski, Marcin  ^[2]; Lukin, Mikhail D. ^[2]

---

1. Harvard University, Cambridge, MA (United States); Harvard University
2. Harvard University, Cambridge, MA (United States)

Reliable quantum computation requires systematic identification and correction of errors that occur and accumulate in quantum hardware. To diagnose and correct such errors, standard quantum error-correcting protocols utilize global error information across the system obtained by mid-circuit readout of ancillary qubits. We investigate circuit-level error-correcting protocols that are measurement-free and based on local error information. Such a local error correction (LEC) circuit consists of faulty multi-qubit gates to perform both syndrome extraction and ancilla-controlled error removal. We develop and implement a reinforcement learning framework that takes a fixed set of faulty gates as inputs and outputs an optimized LEC circuit. To evaluate this approach, we quantitatively characterize an extension of logical qubit lifetime by a noisy LEC circuit. For the two-dimensional (2D) classical Ising model and four-dimensional toric code, our optimized LEC circuit performs better at extending a memory lifetime compared with a conventional LEC circuit based on Toom's rule in a subthreshold gate error regime. We further show that such circuits can be used to reduce the rate of mid-circuit readouts to preserve a 2D toric code memory. Lastly, we discuss the application of the LEC protocol on dissipative preparation of quantum states with topological phases.

• Research Organization: Harvard University, Cambridge, MA (United States)
• Sponsoring Organization: DARPA IMPAQT; DARPA MeasQuIT; DARPA ONISQ; IARPA ELQ; National Science Foundation (NSF); USDOE
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 2499721
• Journal Information: Physical Review A, Journal Name: Physical Review A Journal Issue: 1 Vol. 111; ISSN 2469-9926
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English