Two-Qubit Spectroscopy of Spatiotemporally Correlated Quantum Noise in Superconducting Qubits
Two-Qubit Spectroscopy of Spatiotemporally Correlated Quantum Noise in Superconducting Qubits
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DOI：
10.1103/prxquantum.1.010305
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发表时间：
2019-12
期刊：
影响因子：
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通讯作者：
Uwe von Lupke;F. Beaudoin;Leigh M. Norris;Youngkyu Sung;R. Winik;J. Y. Qiu;M. Kjaergaard;David K. Kim;J. Yoder;S. Gustavsson;L. Viola;W. Oliver
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文献类型：
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作者：
Uwe von Lupke;F. Beaudoin;Leigh M. Norris;Youngkyu Sung;R. Winik;J. Y. Qiu;M. Kjaergaard;David K. Kim;J. Yoder;S. Gustavsson;L. Viola;W. Oliver
在多个量子位之间表现出显著的时间和空间相关性的噪声可能对容错量子计算和量子增强计量学两者特别有害。然而，一个完整的频谱表征的噪声环境，甚至一个双量子比特系统迄今尚未报告。我们提出并实验验证了一个基于连续控制调制的双量子比特退相噪声光谱协议。通过将自旋锁定驰豫法的思想与统计激励的鲁棒估计方法相结合，我们的协议允许同时重建所有单量子比特和双量子比特互相关谱，包括访问其独特的非经典特征。只有单量子比特控制操作和状态断层扫描测量，而不需要纠缠态的准备或读出两个量子比特的可观测量。虽然我们的实验验证使用两个超导量子位耦合到一个共享的工程噪声源，我们的方法是便携式的各种去相位为主的量子位架构。通过将量子噪声光谱学推到单量子位设置之外，我们的工作为表征工程和自然发生的噪声环境中的时空相关性铺平了道路。
Noise that exhibits significant temporal and spatial correlations across multiple qubits can be especially harmful to both fault-tolerant quantum computation and quantum-enhanced metrology. However, a complete spectral characterization of the noise environment of even a two-qubit system has not been reported thus far. We propose and experimentally validate a protocol for two-qubit dephasing noise spectroscopy based on continuous control modulation. By combining ideas from spin-locking relaxometry with a statistically motivated robust estimation approach, our protocol allows for the simultaneous reconstruction of all the single-qubit and two-qubit cross-correlation spectra, including access to their distinctive non-classical features. Only single-qubit control manipulations and state-tomography measurements are employed, with no need for entangled-state preparation or readout of two-qubit observables. While our experimental validation uses two superconducting qubits coupled to a shared engineered noise source, our methodology is portable to a variety of dephasing-dominated qubit architectures. By pushing quantum noise spectroscopy beyond the single-qubit setting, our work paves the way to characterizing spatiotemporal correlations in both engineered and naturally occurring noise environments.