Southwest Quantum Information and Technology

Erasure qubits: Overcoming the T1 limit in superconducting circuits

Presenting Author: Aleksander Kubica, AWS Center for Quantum Computing
Contributing Author(s): Arbel Haim, Yotam Vaknin, Fernando Brandao, Alex Retzker

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.

Read this article online: http://arxiv.org/abs/2208.05461

(Session 10 : from 9:45 am - 10:15 am)