State leakage during fast decay and control of a superconducting transmon qubit
State leakage during fast decay and control of a superconducting transmon qubit
复制标题
快速衰减过程中的状态泄漏和超导传输量子位的控制
DOI：
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发表时间：
2020
影响因子：
7.6
通讯作者：
T. Ala‐Nissila
中科院分区：
文献类型：
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作者：
A. Babu;J. Tuorila;T. Ala‐Nissila
超导约瑟夫森结量子比特构成了许多应用的主要当前技术，包括可扩展的量子计算机和热器件。这类系统的理论建模通常在两级近似内完成。然而，精确的理论建模需要考虑高激发态的影响，而不是将系统限制在两级量子位子空间。在这里，我们使用数值精确的随机Liouville-von Neumann方程方法研究超导transmon的动力学和控制。我们重点研究了理想二能级子空间的状态泄漏在槽诱导衰变和单量子比特门操作中的作用。由于与槽体的强耦合，我们发现了显著的短时间状态泄漏。我们量化了单量子比特门的泄漏误差，并演示了在退相干存在下，用导数去除绝热门（DRAG）控制对五能级transmon的泄漏误差的抑制。我们的研究结果预测了两级近似的精度限制，以及量子比特动力学和实验相关参数集控制中可能存在的内在约束。
Superconducting Josephson junction qubits constitute the main current technology for many applications, including scalable quantum computers and thermal devices. Theoretical modeling of such systems is usually done within the two-level approximation. However, accurate theoretical modeling requires taking into account the influence of the higher excited states without limiting the system to the two-level qubit subspace. Here, we study the dynamics and control of a superconducting transmon using the numerically exact stochastic Liouville–von Neumann equation approach. We focus on the role of state leakage from the ideal two-level subspace for bath induced decay and single-qubit gate operations. We find significant short-time state leakage due to the strong coupling to the bath. We quantify the leakage errors in single-qubit gates and demonstrate their suppression with derivative removal adiabatic gates (DRAG) control for a five-level transmon in the presence of decoherence. Our results predict the limits of accuracy of the two-level approximation and possible intrinsic constraints in qubit dynamics and control for an experimentally relevant parameter set.