Electrical control of the hole spin qubit in Si and Ge nanowire quantum dots

Milivojević, Marko

doi:10.1103/physrevb.104.235304

Cited by 12 publications

(12 citation statements)

References 51 publications

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“…We arrive at the same form of the effective 2 × 2 Hamiltonian as in Eq. (47). However, the effective masses and the SOI depend now also on the electric field gradient |δE| , see Fig.…”

Section: Inhomogeneous Electric Fieldmentioning

confidence: 93%

“…In this section, we analyze how the details of the confinement affect the parameters of the effective model, H 2×2 , introduced in Eq. (47). In particular we consider a one-dimensional channel defined by gates in a planar Ge/SiGe heterostructure as shown in Fig.…”

Section: One-dimensional Channelmentioning

confidence: 99%

“…We use the resulting matrix and perform a second order perturbation theory with respect to the ground state subspace (ϕ ↑ 2 , ϕ ↓ 0 ) and we project the results onto this subspace, yielding the effective 2 × 2 model in Eq. (47).…”

Section: Appendix A: Bulk Dispersion Relationmentioning

confidence: 99%

“…In particular, the largest SOI arises in quasione-dimensional architectures, including Ge nanowires (NWs) [1,9,24,47] and gate-defined squeezed QDs in planar heterostructures [25]. In these systems, experiments have shown a large proximity-induced superconductivity [48][49][50], making hole NWs promising candidates for topological quantum information processing based on MBSs [51][52][53][54][55][56][57][58][59][60][61].…”

Section: Introductionmentioning

confidence: 99%

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Enhanced orbital magnetic field effects in Ge hole nanowires

Adelsberger¹,

Bosco²,

Klinovaja³

et al. 2022

Preprint

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Hole semiconductor nanowires (NW) are promising platforms to host spin qubits and Majorana bound states for topological qubits because of their strong spin-orbit interactions (SOI). The properties of these systems depend strongly on the design of the cross section and on strain, as well as on external electric and magnetic fields. In this work, we analyze in detail the dependence of the SOI and g factors on the orbital magnetic field. We focus on magnetic fields aligned along the axis of the NW, where orbital effects are enhanced and result in a renormalization of the effective g factor up to 400 %, even at small values of magnetic field. We provide an exact analytical solution for holes in Ge NWs and we derive an effective low-energy model that enables us to investigate the effect of electric fields applied perpendicular to the NW. We also discuss in detail the role of strain, growth direction, and high energy valence bands in different architectures, including Ge/Si core/shell NWs, gate-defined one-dimensional channels in planar Ge, and curved Ge quantum wells. In core/shell NWs grown along the [110] direction the g factor can be twice larger than for other growth directions which makes this growth direction advantageous for Majorana bound states. Also curved Ge quantum wells feature large effective g factors and SOI, again ideal for hosting Majorana bound states. Strikingly, because these quantities are independent of the electric field, hole spin qubits encoded in curved quantum wells are to good approximation not susceptible to charge noise, significantly boosting their coherence time.

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“…We arrive at the same form of the effective 2 × 2 Hamiltonian as in Eq. (47). However, the effective masses and the SOI depend now also on the electric field gradient |δE| , see Fig.…”

Section: Inhomogeneous Electric Fieldmentioning

confidence: 93%

Section: One-dimensional Channelmentioning

confidence: 99%

Section: Appendix A: Bulk Dispersion Relationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Enhanced orbital magnetic field effects in Ge hole nanowires

Adelsberger¹,

Bosco²,

Klinovaja³

et al. 2022

Preprint

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show abstract

“…Quasi-1D hole gas achieved in semiconductor nanowire is attracting increasing interest recently [27][28][29][30][31][32][33][34][35][36][37]. The hole gas in 1D exhibits peculiar properties that cannot be anticipated from the counterpart properties in 2D.…”

Section: Introductionmentioning

confidence: 99%

Two-band description of the strong `spin'-orbit coupled one-dimensional hole gas

Li¹,

Qi²

2022

Preprint

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Strong 'spin'-orbit coupled one-dimensional hole gas is achievable in an unstrained Ge nanowire in the presence of a strong magnetic field. Basing on the Luttinger-Kohn Hamiltonian in the spherical approximation, we show this strong 'spin'-orbit coupled one-dimensional hole gas can be accurately described by an effective two-band Hamiltonian H ef = 2 k 2 z /(2m * h )+ασ z kz +g * h µBBσ x /2, as long as the magnetic field is purely longitudinal or purely transverse. The explicit magnetic field dependent expressions of the 'spin'-orbit coupling α ≡ α(B) and the effective g-factor g * h ≡ g * h (B) are given. When the magnetic field is applied in an arbitrary direction, the two-band Hamiltonian description is still a good approximation.

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Ultrafast and Electrically Tunable Rabi Frequency in a Germanium Hut Wire Hole Spin Qubit

Wang

Gao

et al. 2023

Nano Lett.

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Hole spin qubits based on germanium (Ge) have strong tunable spin−orbit interaction (SOI) and ultrafast qubit operation speed. Here we report that the Rabi frequency (f Rabi ) of a hole spin qubit in a Ge hut wire (HW) double quantum dot (DQD) is electrically tuned through the detuning energy (ϵ) and middle gate voltage (V M ). f Rabi gradually decreases with increasing ϵ; on the contrary, f Rabi is positively correlated with V M . We attribute our results to the change of electric field on SOI and the contribution of the excited state in quantum dots to f Rabi . We further demonstrate an ultrafast f Rabi exceeding 1.2 GHz, which indicates the strong SOI in our device. The discovery of an ultrafast and electrically tunable f Rabi in a hole spin qubit has potential applications in semiconductor quantum computing.

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Electrical control of the hole spin qubit in Si and Ge nanowire quantum dots

Cited by 12 publications

References 51 publications

Enhanced orbital magnetic field effects in Ge hole nanowires

Enhanced orbital magnetic field effects in Ge hole nanowires

Two-band description of the strong `spin'-orbit coupled one-dimensional hole gas

Ultrafast and Electrically Tunable Rabi Frequency in a Germanium Hut Wire Hole Spin Qubit

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