Quantum-bath-driven decoherence of mixed spin systems
Quantum-bath-driven decoherence of mixed spin systems
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DOI：
10.1103/physrevb.89.045403
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发表时间：
2014-01-08
影响因子：
3.7
通讯作者：
Monteiro, T. S.
中科院分区：
文献类型：
--
作者：
Balian, S. J.;Wolfowicz, Gary;Monteiro, T. S.
混合电子-核自旋量子比特的退相干是当前非常重要的主题，但仍然缺乏理解：虽然自旋量子比特的重要退相干机制来自于相关性缓慢衰减的量子自旋浴环境，但解释观察到的退相干时间随磁场急剧变化的唯一分析框架是基于经典噪声的抑制。在这里，我们得到了一个一般的表达式的中心自旋系统的消相干时间，揭示了显着的差异量子浴消相干和经典场噪声的消相干。我们使用电子自旋共振（ESR）和核磁共振（NMR）跃迁对天然硅中铋供体的退相干时间进行测量，在这两种情况下，在很宽的参数范围内都与我们的理论非常吻合。我们的表达的普遍性也测试了定量比较与以前的测量退相干周围的“最佳工作点”或“时钟转换”，退相干被强烈抑制。我们进一步验证了我们的研究结果相比，集群扩展模拟。
The decoherence of mixed electron-nuclear spin qubits is a topic of great current importance, but understanding is still lacking: While important decoherence mechanisms for spin qubits arise from quantum spin bath environments with slow decay of correlations, the only analytical framework for explaining observed sharp variations of decoherence times with magnetic field is based on the suppression of classical noise. Here we obtain a general expression for decoherence times of the central spin system which exposes significant differences between quantum-bath decoherence and decoherence by classical field noise. We perform measurements of decoherence times of bismuth donors in natural silicon using both electron spin resonance (ESR) and nuclear magnetic resonance (NMR) transitions, and in both cases find excellent agreement with our theory across a wide parameter range. The universality of our expression is also tested by quantitative comparisons with previous measurements of decoherence around "optimal working points" or "clock transitions" where decoherence is strongly suppressed. We further validate our results by comparison to cluster expansion simulations.