Haggai Landa: "Stabilizer dynamics with IBM Quantum devices and implications to error-correction decoding"

07 May 2024
Weekly seminar
Solid State Auditorium

IBM Quantum devices are accessible via the cloud and allow users free access for running quantum computation and quantum dynamics experiments. I will present a detailed experimental characterization of the noise model of idle qubits on the 127-qubit devices, accounting for qubit spontaneous emission, finite temperature, dephasing, frequency drifts, charge-parity (quasiparticle) oscillations, crosstalk (“ZZ” coupling) and initialization and readout errors. Using this model, we study the decay dynamics of stabilizers characterizing graph states, and their protection using tailored dynamical-decoupling sequences suppressing both single-qubit and interaction terms [1]. We then employ this noise model to analyze how different approximations of the noise capture the performance of the five-qubit error correction code in recovering a decaying quantum memory logical qubit. We find that the commonly used single-qubit Pauli channel completely fails, and a two-qubit Pauli approximation is sensitive to the details of the noise, state, and decoder, accurate in many cases only at short timescales. We calculate the code pseudo-threshold emerging within this model and demonstrate how knowledge of the qubit parameters and connectivity can be used to design better decoders [2].


[1] L. Shirizly, G. Misguich, H. Landa, Dissipative Dynamics of Graph-State Stabilizers with Superconducting Qubits, Phys. Rev. Lett. 132, 010601 (2024).


[2] Z. Schwartzman-Nowik, L. Shirizly, H. Landa, Modeling error correction with Lindblad dynamics and approximate channels, arXiv:2402.16727.