Hyperfine-phonon spin relaxation in a single-electron GaAs quantum dot.
Hyperfine-phonon spin relaxation in a single-electron GaAs quantum dot.
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DOI：
10.1038/s41467-018-05879-x
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发表时间：
2018-08-27
影响因子：
16.6
通讯作者：
Zumbühl DM
中科院分区：
文献类型：
--
作者：
Camenzind LC;Yu L;Stano P;Zimmerman JD;Gossard AC;Loss D;Zumbühl DM
理解和控制自旋弛豫时间T1是基于自旋的量子比特的关键挑战之一。较大的T1通常是有利的，为量子位相干性和自旋读出保真度设置基本上限。在低温和高面内磁场B下，GaAs量子点的自旋弛豫依赖于声子发射和自旋轨道耦合。特性依赖性T1 = B-5和明显的B场各向异性已经在实验中得到证实。然而，15年前也有人预测，在足够低的磁场下，自旋-轨道相互作用被与核自旋的耦合所取代，弛豫变为各向同性，标度变为T1 B−3。在这里，我们通过在前所未有的磁场范围内测量T1（通过较低的温度使之成为可能），并在最低场下报告最大T1 = 57 ± 15 s，从而在纳米结构中创造了电子自旋寿命的记录。基于自旋的量子比特的应用要求理解和控制自旋弛豫时间T1，这仍然具有挑战性。实验证明了GaAs量子点中单电子自旋的自旋弛豫机制是通过超精细相互作用和长自旋弛豫时间T1 ~ 57 s实现的。
Understanding and control of the spin relaxation time T1 is among the key challenges for spin-based qubits. A larger T1 is generally favored, setting the fundamental upper limit to the qubit coherence and spin readout fidelity. In GaAs quantum dots at low temperatures and high in-plane magnetic fields B, the spin relaxation relies on phonon emission and spin–orbit coupling. The characteristic dependence T1 ∝ B−5 and pronounced B-field anisotropy were already confirmed experimentally. However, it has also been predicted 15 years ago that at low enough fields, the spin–orbit interaction is replaced by the coupling to the nuclear spins, where the relaxation becomes isotropic, and the scaling changes to T1 ∝ B−3. Here, we establish these predictions experimentally, by measuring T1 over an unprecedented range of magnetic fields—made possible by lower temperature—and report a maximum T1 = 57 ± 15 s at the lowest fields, setting a record electron spin lifetime in a nanostructure. The application of spin based qubits requests understanding and control of spin relaxation time T1 which remains challenging. Here the authors experimentally demonstrate the spin relaxation mechanism via hyper fine interaction and long spin-relaxation time T1 ~ 57 s for a single electron spin in GaAs quantum dot.
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