标题： 电子自旋量子比特在半导体量子点中的去极化 显示英文标题

标题： Depolarization of Electronic Spin Qubits Confined in Semiconductor Quantum Dots

摘要： 量子点可以说是物质自旋量子比特和飞行光子量子比特之间最好的接口。 使用量子点器件来产生联合自旋-光子态需要电子自旋量子比特能够长时间存储。 因此，研究各种量子点束缚电荷载体的自旋相干性在科学和技术上都非常重要。 在本研究中，我们报告了对同一量子点中五种不同形式的电子自旋量子比特进行的自旋弛豫测量。 特别是，我们使用所有光学技术来测量束缚重空穴的自旋弛豫以及暗激子的自旋弛豫——一种具有平行自旋的长寿命电子-重空穴对。 在没有外加磁场的情况下，我们测量的电子、重空穴、暗激子、负三重态和正三重态的自旋弛豫结果与中心自旋理论一致，该理论将载流子自旋的去相位归因于它们与构成量子点的原子核自旋之间的超精细相互作用。 我们证明重空穴的去相位比电子慢得多。 我们还通过实验和理论表明，由于电子-空穴交换相互作用，暗激子的去相位比重空穴慢，这种相互作用部分保护其自旋状态免受去相位的影响。 显示英文摘要

摘要： Quantum dots are arguably the best interface between matter spin qubits and flying photonic qubits. Using quantum dot devices to produce joint spin-photonic states requires the electronic spin qubits to be stored for extended times. Therefore, the study of the coherence of spins of various quantum dot confined charge carriers is important both scientifically and technologically. In this study we report on spin relaxation measurements performed on five different forms of electronic spin qubits confined in the very same quantum dot. In particular, we use all optical techniques to measure the spin relaxation of the confined heavy hole and that of the dark exciton - a long lived electron-heavy hole pair with parallel spins. Our measured results for the spin relaxation of the electron, the heavy-hole, the dark exciton, the negative and the positive trions, in the absence of externally applied magnetic field, are in agreement with a central spin theory which attributes the dephasing of the carriers' spin to their hyperfine interactions with the nuclear spins of the atoms forming the quantum dots. We demonstrate that the heavy hole dephases much slower than the electron. We also show, both experimentally and theoretically, that the dark exciton dephases slower than the heavy hole, due to the electron-hole exchange interaction, which partially protects its spin state from dephasing.