Fast and high-fidelity dispersive readout of a spin qubit with squeezed microwave and resonator nonlinearity

IF 6.6 1区物理与天体物理 Q1 PHYSICS, APPLIED

npj Quantum Information Pub Date : 2024-12-28 DOI:10.1038/s41534-024-00924-8

Chon-Fai Kam, Xuedong Hu

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Abstract

Fast and high-fidelity qubit measurement is essential for quantum error correction in universal quantum computing. This study examines dispersive measurement of a spin in a semiconductor double quantum dot using a nonlinear microwave resonator. By employing displaced squeezed vacuum states, we achieve rapid, high-fidelity readout for silicon spin qubits. Our results show that modest squeezing and mild nonlinearity significantly enhance the signal-to-noise ratio (SNR) and the fidelity of qubit-state readout. By optimally adjusting the phases of squeezing and nonlinearity, we reduce readout time to sub-microsecond ranges. With current technology parameters (κ ≈ 2χ_s, χ_s/(2π) ≈ 0.15 MHz), utilizing a displaced squeezed vacuum state with 30 photons and a modest squeezing parameter r ≈ 0.6, along with a nonlinear microwave resonator charactered by a strength of λ ≈ − 1.2χ_s, a readout fidelity of 98% can be attained within a readout time of around 0.6 μs.

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具有压缩微波和谐振器非线性的自旋量子比特的快速高保真色散读出

快速、高保真的量子比特测量是通用量子计算中量子纠错的关键。本研究利用非线性微波谐振器对半导体双量子点的自旋进行色散测量。通过使用位移压缩真空态，我们实现了硅自旋量子比特的快速、高保真读出。我们的研究结果表明，适度的压缩和轻微的非线性显著提高了量子比特状态读出的信噪比和保真度。通过优化调整压缩和非线性的相位，我们将读出时间减少到亚微秒范围。在现有的技术参数（κ≈2χs, χs/(2π)≈0.15 MHz）下，利用30个光子的位移压缩真空状态，适当的压缩参数r≈0.6，以及强度λ≈−1.2χs的非线性微波谐振器，在0.6 μs左右的读出时间内，可以获得98%的读出保真度。

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来源期刊

npj Quantum Information Computer Science-Computer Science (miscellaneous)

CiteScore

13.70

自引率

3.90%

发文量

130

审稿时长

29 weeks

期刊介绍： The scope of npj Quantum Information spans across all relevant disciplines, fields, approaches and levels and so considers outstanding work ranging from fundamental research to applications and technologies.