论文标题

擦除量表:克服超导电路的$ T_1 $限制

Erasure qubits: Overcoming the $T_1$ limit in superconducting circuits

论文作者

Kubica, Aleksander, Haim, Arbel, Vaknin, Yotam, Brandão, Fernando, Retzker, Alex

论文摘要

长期以来,振幅阻尼时间$ t_1 $一直是超导电路中量子保真度的主要因素,促使旨在增加$ t_1 $的量子材料科学和设计方面的共同努力。相比之下,通常可以将DEPHASING时间扩展到$ T_1 $(例如,动态解耦)以上,以至于它不限制Fidelity。在本文中,我们提出了一个方案,以通过设计量子位以一种可以检测到振幅阻尼错误并转换为擦除错误的方式来克服常规$ t_1 $限制对富达的限制。与标准Qubit实施相比,我们的方案提高了易耐故障协议的性能,如表面代码的电路噪声模拟所证明的那样。我们用超导电路描述了两个简单的量子实现,并讨论了检测振幅阻尼错误,执行纠缠门和扩展$ t_ϕ $的程序。我们的结果表明,工程工作应该集中于改善$ t_ϕ $和量子相干控制的质量,因为它们有效地成为了耐故障协议的限制因素。

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, $T_ϕ$, 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 $T_ϕ$. Our results suggest that engineering efforts should focus on improving $T_ϕ$ and the quality of quantum coherent control, as they effectively become the limiting factor on the performance of fault-tolerant protocols.

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