Emergence of strong tunable linear Rashba spin-orbit coupling in two-dimensional hole gases in semiconductor quantum wells

Xiong, Jia-Xin; Guan, Shaokang; Luo, Jun-Wei; Li, Shu-Shen

doi:10.1103/physrevb.103.085309

Cited by 31 publications

(14 citation statements)

References 93 publications

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“…[27] shows that the isotropic approximation describes well the system, but there are special orientations at which the DRSOI is enhanced: the DRSOI is largest when z [110] and y [001] [17,27]. In contrast to other proposals [20] for obtaining DRSOI in Ge heterostructures, in our approach this particular growth direction is convenient but not required. Also, because here the DRSOI originates from the confinement potential and not from the small anisotropies of Ge, the maximal SOI v * is more than 5 times larger than in [20] at comparable electric fields.…”

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confidence: 83%

“…In contrast to other proposals [20] for obtaining DRSOI in Ge heterostructures, in our approach this particular growth direction is convenient but not required. Also, because here the DRSOI originates from the confinement potential and not from the small anisotropies of Ge, the maximal SOI v * is more than 5 times larger than in [20] at comparable electric fields.…”

mentioning

confidence: 99%

“…Our approach is based on a squeezed dot, where one of the lateral directions is tightly confined. This design takes full advantage of the hole physics by recovering the large DRSOI typical of wires and in contrast to alternative proposals [20] only weakly depends on the growth direction of the heterostructure. The DRSOI also opens up to the possibility of strongly coupling these qubits to microwave resonators [21,22], potentially enabling long-range interactions between distant qubits and surface code architecture [23].…”

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confidence: 99%

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Squeezed hole spin qubits in Ge quantum dots with ultrafast gates at low power

Bosco,

Benito,

Adelsberger

et al. 2021

Preprint

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Hole spin qubits in planar Ge heterostructures are one of the frontrunner platforms for scalable quantum computers. In these systems, the spin-orbit interactions permit efficient all-electric qubit control. We propose a minimal design modification of planar devices that enhances these interactions by orders of magnitude and enables low power ultrafast qubit operations in the GHz range. Our approach is based on an asymmetric potential that strongly squeezes the quantum dot in one direction. This confinement-induced spin-orbit interaction does not rely on microscopic details of the device such as growth direction or strain, and could be turned on and off on demand in state-of-the-art qubits.

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confidence: 83%

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confidence: 99%

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confidence: 99%

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Squeezed hole spin qubits in Ge quantum dots with ultrafast gates at low power

Bosco,

Benito,

Adelsberger

et al. 2021

Preprint

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“…The parameter β so is material-dependent and depends also in an intricate way on the exact shape of the transverse confining potential. By focusing solely on this Rashba term, we neglect the Dresselhaus contribution stemming from the lack of a crystallographic inversion center (which can contribute to the SOI in materials like GaAs and InAs) and we disregard the "direct" Rashba SOI due to HH-LH mixing [31][32][33][34]68]. With this choice, the analysis that follows is most relevant for quantum dots hosted in materials with a large Rashba coefficient.…”

Section: Confined Heavy Holesmentioning

confidence: 99%

Anisotropic $g$-tensors in hole quantum dots: The role of the transverse confinement direction

Qvist¹,

Danon²

2021

Preprint

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Qubits encoded in the spin state of heavy holes confined in Si-and Ge-based semiconductor quantum dots are currently leading the efforts toward spin-based quantum information processing. The virtual absence of spinful nuclei in purified samples yields long qubit coherence times and the intricate coupling between spin and momentum in the valence band can provide very fast spinorbit-based qubit control, e.g., via electrically induced modulations of the heavy-hole g-tensor. A thorough understanding of all aspects of the interplay between spin-orbit coupling, the confining potentials, and applied magnetic fields is thus quintessential for the development of the optimal hole-spin-based qubit platform. Here we theoretically investigate the manifestation of the effective g-tensor and effective mass of heavy holes in two-dimensional hole gases as well as in lateral quantum dots. We include the effects of the anisotropy of the effective Luttinger Hamiltonian (particularly relevant for Si-based systems) and we focus on the detailed role of the orientation of the transverse confining potential. We derive most general analytic expressions for the anisotropic g-tensor and we present a general and straightforward way to calculate corrections to this g-tensor for localized holes due to various types of spin-orbit interaction, exemplifying the approach by including a simple linear Rashba-like term. Our results thus contribute to the understanding needed to find optimal points in parameter space for hole-spin qubits, where confinement is effective and spin-orbit-mediated electric control over the spin states is efficient.

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“…We call this orientation direct Rashba axes (DRA) [37] because it guarantees the largest DRSOI in wires [6,7,50]. First, because of the sizeable HH-LH mixing even in planar heterostructures, yielding DRSOI [51], the hyperfine interactions are non-Ising at L x /L y 1. The hyperfine anisotropy is still pronounced in wide Ge wires, but it decreases notably in Si, where the spin decay remains Gaussian with times T i 0 of hundreds of nanoseconds.…”

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confidence: 99%

Fully tunable hyperfine interactions of hole spin qubits in Si and Ge quantum dots

Bosco,

Loss

2021

Preprint

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Hole spin qubits are frontrunner platforms for scalable quantum computers, but state-of-theart devices suffer from noise originating from the hyperfine interactions with nuclear defects. We show that these interactions have a highly tunable anisotropy that is controlled by device design and external electric fields. This tunability enables sweet spots where the hyperfine noise is suppressed by an order of magnitude and is comparable to isotopically purified materials. We identify surprisingly simple designs where the qubits are highly coherent and are largely unaffected by both charge and hyperfine noise. We find that the large spin-orbit interaction typical of elongated quantum dots not only speeds up qubit operations, but also dramatically renormalizes the hyperfine noise, altering qualitatively the dynamics of driven qubits and enhancing the fidelity of qubit gates. Our findings serve as guidelines to design high performance qubits for scaling up quantum computers.

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Emergence of strong tunable linear Rashba spin-orbit coupling in two-dimensional hole gases in semiconductor quantum wells

Cited by 31 publications

References 93 publications

Squeezed hole spin qubits in Ge quantum dots with ultrafast gates at low power

Squeezed hole spin qubits in Ge quantum dots with ultrafast gates at low power

Anisotropic $g$-tensors in hole quantum dots: The role of the transverse confinement direction

Fully tunable hyperfine interactions of hole spin qubits in Si and Ge quantum dots

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