Double-layer-gate architecture for few-hole GaAs quantum dots

Abstract

Article:Wang, D.Q., Hamilton, A.R., Farrer, I. orcid.org/0000-0002-3033-4306 et al. (2 more authors) (2016) Double-layer-gate architecture for few-hole GaAs quantum dots. Nanotechnology, 27 (33). https://doi.org/10.1088/0957-4484/27/33/334001 This is an author-created, un-copyedited version of an article accepted for publication/published in Nanotechnology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0957-4484/27/33/334001. eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Abstract. We report the fabrication of single and double hole quantum dots using a double-layer-gate design on an undoped accumulation mode AlxGa 1−x As/GaAs heterostructure. Electrical transport measurements of a single quantum dot show varying addition energies and clear excited states. In addition, the two-level-gate architecture can also be configured into a double quantum dot with tunable inter-dot coupling. † Present Address:

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

“…By translating the corresponding voltage through the lever arm values for our sample, we extract the effective hole g-factor g * ⊥ = ∆E(B)/µ B B = 1.45±0.1 for the left-hand (doubly-occupied) dot. This value is consistent with Wang et al [30]. We repeated the experiment using the transition (1,1)→(0,2) with the opposite source-drain voltage and obtained the same g * ⊥ for the right-hand dot.…”

Spin-orbit enabled quantum transport channels in a two-hole double quantum dot

“…This spin-to-charge conversion is routinely used as a readout step in electron spin coherent control algorithms, 27,[29][30][31][32][33][34] and has also been demonstrated in Si and Ge-based hole devices, as well as in the GaAs/AlGaAs double quantum dot confining many holes. 19,20 In our system, however, the spin-flip tunneling lifts the spin blockade. 23 As a result, we are able to map out the complete energy spectrum of the confined two-hole system as a function of the detuning between the two dots and the external magnetic field by performing transport spectroscopy measurements in the large source-drain bias regime.…”

“…[21][22][23][24] The Ti/Au gates are deposited atop the undoped wafer with the GaAs/ Al x Ga 1−x As (x=50%) hetero-interface positioned 65 nm below the surface. The two-dimensional hole gas (2DHG) is accumulated at this hetero-interface by a global top (11) and (20) charge configurations denoted in panel (c) by the red rectangle. (e) A similar transport diagram for the opposite source-drain bias voltage V SD = −2 mV, in the same stability region.…”

“…Further, we add holes one by one to achieve the total occupation of two holes, realized as charge configurations (20), (11), or (02), as labeled in the diagram.…”

“…[4][5][6][7][8][9] Presently, the main technological effort towards implementation of the hole spin-based qubits is concentrated in several material platforms: complementary metal-oxide-semiconductor silicon devices, 6,7 silicon gated devices, 10 the Ge/Si hut quantum wires, 8,[11][12][13] Ge/Si core-shell nanowires 14,15 and nanocrystals, 16 Ge/SiGe planar heterostructures, 17,18 and GaAs/AlGaAs gated devices. 9,[19][20][21][22][23][24] Since the Si and Ge crystal lattice possesses inversion symmetry, these systems exhibit only the Rashba SOI, which can be tuned, and in principle even switched off, by appropriate choices of gate voltages. 4,25 In GaAs/AlGaAs planar heterostructures, on the other hand, both Dresselhaus and Rashba SOIs are present, with the former determining the spin relaxation time.…”