Quadrupolar and anisotropy effects on dephasing in two-electron spin qubits in GaAs.
Quadrupolar and anisotropy effects on dephasing in two-electron spin qubits in GaAs.
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DOI：
10.1038/ncomms11170
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发表时间：
2016-04-15
影响因子：
16.6
通讯作者：
Bluhm H
中科院分区：
文献类型：
--
作者：
Botzem T;McNeil RP;Mol JM;Schuh D;Bougeard D;Bluhm H
理解半导体中电子自旋由于与核自旋的相互作用而产生的退相干具有根本意义，因为它们实现了中心自旋模型，并且对于将它们用作量子比特具有实际意义。有趣的效果出现从四极相互作用的核自旋与电场梯度，这已被证明是抑制扩散核自旋动力学，从而可能提高电子自旋相干。在这里，我们的实验表明，对于栅极定义的GaAs量子点，核拉莫尔进动的四极加宽，通过引起更快的去相关的横向核场，降低了电子自旋相干性。然而，这种效果消失了适当的磁场方向。此外，我们观察到归因于各向异性电子g张量的相干性的额外调制。这些结果完成了我们对门控量子点失相的理解，并指出了缓解策略。它们也可能有助于解开自组装量子点和III-V纳米线中无法解释的行为。 半导体中的电子自旋形成了量子信息技术的潜在基础，然而它们受到与核自旋相互作用的强烈影响。在这里，作者展示了四极相互作用，虽然抑制核动力学，可以导致电子退相干的各向异性增强。
Understanding the decoherence of electron spins in semiconductors due to their interaction with nuclear spins is of fundamental interest as they realize the central spin model and of practical importance for using them as qubits. Interesting effects arise from the quadrupolar interaction of nuclear spins with electric field gradients, which have been shown to suppress diffusive nuclear spin dynamics and might thus enhance electron spin coherence. Here we show experimentally that for gate-defined GaAs quantum dots, quadrupolar broadening of the nuclear Larmor precession reduces electron spin coherence by causing faster decorrelation of transverse nuclear fields. However, this effect disappears for appropriate field directions. Furthermore, we observe an additional modulation of coherence attributed to an anisotropic electronic g-tensor. These results complete our understanding of dephasing in gated quantum dots and point to mitigation strategies. They may also help to unravel unexplained behaviour in self-assembled quantum dots and III–V nanowires. Electron spins in semiconductors form a potential basis for quantum information technology however they are strongly affected by interactions with nuclear spins. Here, the authors show how quadrupolar interactions, although suppressing nuclear dynamics, can result in an anisotropic enhancement of electronic decoherence.