IQIM Postdoctoral and Graduate Student Seminar

Abstract: The amplitude damping time, T_1, has long stood as the major factor limiting quantum fidelity in superconducting circuits, prompting concerted efforts in the material science and design of qubits aimed at increasing T_1. In contrast, the dephasing time, T_\phi, can usually be extended above T_1 (via, e.g., dynamical decoupling), to the point where it does not limit fidelity. In this article we propose a scheme for overcoming the conventional T_1 limit on fidelity by designing qubits in a way that amplitude damping errors can be detected and converted into erasure errors. Compared to standard qubit implementations our scheme improves the performance of fault-tolerant protocols, as numerically demonstrated by the circuit-noise simulations of the surface code. We describe two simple qubit implementations with superconducting circuits and discuss procedures for detecting amplitude damping errors, performing entangling gates, and extending T_\phi. Our results suggest that engineering efforts should focus on improving T_\phi and the quality of quantum coherent control, as they effectively become the limiting factor on the performance of fault-tolerant protocols.

Reference: http://arxiv.org/abs/2208.05461

Lunch will be provided, following the talk, on the lawn north of the Bridge Arcade

Attendees joining in person must demonstrate that they comply with Caltech's vaccination requirements (present Caltech ID or AWS ID or vaccination and booster confirmation).