Gillard George, Clarke Edmund, Chekhovich Evgeny A
Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, UK.
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, S1 3JD, UK.
Nat Commun. 2022 Jul 13;13(1):4048. doi: 10.1038/s41467-022-31618-4.
There is a growing interest in hybrid solid-state quantum systems where nuclear spins, interfaced to the electron spin qubit, are used as quantum memory or qubit register. These approaches require long nuclear spin coherence, which until now seemed impossible owing to the disruptive effect of the electron spin. Here we study InGaAs semiconductor quantum dots, demonstrating millisecond-long collective nuclear spin coherence even under inhomogeneous coupling to the electron central spin. We show that the underlying decoherence mechanism is spectral diffusion induced by a fluctuating electron spin. These results provide new understanding of the many-body coherence in central spin systems, required for development of electron-nuclear spin qubits. As a demonstration, we implement a conditional gate that encodes electron spin state onto collective nuclear spin coherence, and use it for a single-shot readout of the electron spin qubit with >99% fidelity.
人们对混合固态量子系统的兴趣与日俱增，在这类系统中，与电子自旋量子比特相耦合的核自旋被用作量子存储器或量子比特寄存器。这些方法需要长寿命的核自旋相干性，而由于电子自旋的干扰效应，到目前为止这似乎是不可能的。在这里，我们研究了铟镓砷半导体量子点，证明了即使在与电子中心自旋的非均匀耦合下，集体核自旋相干性也能持续毫秒级。我们表明，潜在的退相干机制是由波动的电子自旋引起的光谱扩散。这些结果为开发电子-核自旋量子比特所需的中心自旋系统中的多体相干性提供了新的理解。作为一个演示，我们实现了一个条件门，它将电子自旋状态编码到集体核自旋相干性上，并将其用于对电子自旋量子比特进行单次读出，保真度超过99%。
