Anisotropic Pauli Spin Blockade of Holes in a GaAs Double Quantum Dot

Abstract

Electrically defined semiconductor quantum dots are attractive systems for spin manipulation and quantum information processing. Heavy-holes in both Si and GaAs are promising candidates for all-electrical spin manipulation, owing to the weak hyperfine interaction and strong spin-orbit interaction. However, it has only recently become possible to make stable quantum dots in these systems, mainly due to difficulties in device fabrication and stability.Here we present electrical transport measurements on holes in a gate-defined double quantum dot in a GaAs/Al x Ga 1−x As heterostructure. We observe clear Pauli spin blockade and demonstrate that the lifting of this spin blockade by an external magnetic field is highly anisotropic.

Single hole spin relaxation probed by fast single-shot latched charge sensing

“…We note that the values of T 1 , ranging from~400 ns at B = 1.5 T tõ 60 μs at B = 0.5 T, are much longer than those measured to date in hole GaAs samples (e.g.~300 ns at B = 0.5 T in ref. 38 ), but shorter by an order of magnitude than those in Ge-based 34,35 or Si-based devices 37 . This is most likely due to the fact that centrosymmetric lattices such as Si do not exhibit the Dresselhaus SOI, leading to the dominance of the Rashba SOI in the spin relaxation mechanism.…”

“…Measurements in Ge/Si samples suggest T 1 of hundreds of microseconds 34 to submicrosecond values 35 at B~1 T. In the Ge hut wire system, values of tens to a hundred microseconds were recorded for magnetic fields from 0.5 T to 1.5 T 36 . T 1 times of several microseconds in hole Si Complementary Metal Oxide Semiconductor (CMOS) devices 37 , and several nanoseconds in gated GaAs samples at similar fields 38 have been reported. Two-axis coherent control of the hole spin has been demonstrated both in the Ge hut sample 39 and in the Si dots 40 .…”

“…The latched technique was used to demonstrate single-shot high-fidelity spin measurements 44,45 and to extend the sensitivity of the spin detection at large magnetic-field gradients 46 . The spin-to-charge conversion allows measuring T 1 by fitting the leakage current in the Pauli-blockaded state to a theoretical formula describing a relaxation cascade in the electron 3,19,27,47 or hole systems 34,35,37,38 . However, this technique cannot be used directly for our hole GaAs dot because of the strong spin-flip tunneling due to the SOI 48,49 , resulting in the suppression of the spin blockade.…”

Consequences of Spin-Orbit Coupling at the Single Hole Level: Spin-Flip Tunneling and the Anisotropic g Factor

“…In silicon DQDs these interactions are absent, leading to Pauli spin blockade [21][22][23]. On the other hand, early experiments on GaAs DQDs in many-hole regime show the spin-orbit-induced spin-flip transport [25]. In addition, our device provides a lateral confinement for the HH subband only, while the LH orbitals remain extended across the sample volume.…”

Quantum computation based on semiconductor quantum dots

“…These electrons can be moved to dots positioned above the donor measurement qubits, each with a back gate to control the exchange coupling between the donor electron and the electron in the quantum dot 关于空穴自旋比特的研究主要分为砷化镓和硅基两种材料. 在砷化镓材料方面, 2014 年, 美国桑 迪亚国家实验室的 Reno 等 [58] 首次在非掺杂型砷化镓异质结量子点中实现了少空穴的双量子点, 获 得了单个空穴; 2016 年, 澳大利亚 University of New South Wales 的 Hamilton 组 [59] 首次在空穴量子 点中观察到了各向异性的自旋阻塞现象. 在砷化镓上, 对空穴自旋比特的操控还有待进一步的研究.…”