Hardware-Efficient Qubit Control with Single-Flux-Quantum Pulse Sequences
Hardware-Efficient Qubit Control with Single-Flux-Quantum Pulse Sequences
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DOI：
10.1103/physrevapplied.12.014044
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发表时间：
2019-07-24
影响因子：
4.6
通讯作者：
Vavilov, Maxim G.
中科院分区：
文献类型：
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作者：
Li, Kangbo;McDermott, R.;Vavilov, Maxim G.
与微波控制相关的硬件开销是超导量子计算规模扩大的主要障碍。另一种方法是用单通量量子（SFQ）脉冲串照射量子位，脉冲电压的时间积分恰好等于超导通量量子。在这里，我们描述了紧凑的SFQ脉冲序列的推导和数值验证，其中经典比特以大约比量子比特振荡频率高5倍的频率时钟到量子比特，允许可变脉冲到脉冲定时。控制序列由短子序列寄存器的重复流构建，旨在抑制计算流形的泄漏。使用单个全局时钟，高保真（>99.99%）控制在20多个不同频率上谐振的量子位是可能的。SFQ脉冲可以在本地存储，并通过近端经典约瑟夫森数字电路传递给量子位，从而提供了一种流线型、低占地面积的经典协处理器，用于监测错误并反馈给量子位阵列。
The hardware overhead associated with microwave control is a major obstacle to the scale-up of superconducting quantum computing. An alternative approach involves irradiation of the qubits with trains of single-flux-quantum (SFQ) pulses, pulses of voltage whose time integral is precisely equal to the superconducting flux quantum. Here, we describe the derivation and numerical validation of compact SFQ pulse sequences in which classical bits are clocked to the qubit at a frequency that is roughly a factor 5 higher than the qubit oscillation frequency, allowing for variable pulse-to-pulse timing The control sequences are constructed by repeated streaming of short subsequence registers that are designed to suppress leakage out of the computational manifold. With a single global clock, high-fidelity (>99.99%) control of qubits resonating at over 20 distinct frequencies is possible. SFQ pulses can be stored locally and delivered to the qubits via a proximal classical Josephson digital circuit, offering the possibility of a streamlined, low-footprint classical coprocessor for monitoring errors and feeding back to the qubit array.