Two-band description of the strong ‘spin’-orbit coupled one-dimensional hole gas in a cylindrical Ge nanowire

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The electron (hole) spin-photon interaction is studied in an asymmetrical InSb (Ge) nanowire quantum dot. The spin-orbit coupling in the quantum dot mediates not only a transverse spin-photon interaction, but also a longitudinal spin-photon interaction due to the asymmetry of the confining potential. Both the transverse and the longitudinal spin-photon interactions have non-monotonic dependence on the spin-orbit coupling. For realistic spin-orbit coupling in the quantum dot, the longitudinal spin-photon interaction is much (at least one order) smaller than the transverse spin-photon interaction. The order of the transverse spin-photon interaction is about 1 nm in terms of length $|z_{eg}|$, or 0.1 MHz in terms of frequency $eE_{0}|z_{eg}|/h$ for a moderate cavity electric field strength $E_{0}=0.4$ V/m. 

Section: Results In a Ge Nanowire Quantum Dotmentioning

confidence: 67%

Section: Results In a Ge Nanowire Quantum Dotmentioning

confidence: 93%

Section: Results In a Ge Nanowire Quantum Dotmentioning

confidence: 96%

Section: Results In a Ge Nanowire Quantum Dotmentioning

confidence: 99%

Section: Results In a Ge Nanowire Quantum Dotmentioning

confidence: 99%

See 3 more Smart Citations

Spin-photon interaction in a nanowire quantum dot with asymmetrical confining potential

2024

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Low-energy hole subband dispersions in a cylindrical Ge nanowire: the effects of the nanowire growth direction

2023

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We examine the validity of the spherical approximation $\gamma_{s}=(2\gamma_{2}+3\gamma_{3})/5$ in the Luttinger-Kohn Hamiltonian in calculating the subband dispersions of the hole gas. We calculate the realistic hole subband dispersions (without the spherical approximation) in a cylindrical Ge nanowire by using quasi-degenerate perturbation theory. The realistic low-energy hole subband dispersions have a double-well anticrossing structure, that consists with the spherical approximation prediction. However, the realistic subband dispersions are also nanowire growth direction dependent. When the nanowire growth direction is restricted in the (100) crystal plane, the detailed growth direction dependences of the subband parameters are given. We find the spherical approximation is good approximation, it can nicely reproduce the real result in some special growth directions.

Hole subband dispersions in a cylindrical Ge nanowire: exact results based on the axial Luttinger–Kohn Hamiltonian

Li (李睿)

2024

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Based on the Luttinger-Kohn Hamiltonian in the axial approximation, the transcendental equations determining the hole subband dispersions in a cylindrical Ge nanowire are analytically derived. These equations are more general than that derived using the spherical approximation, and are suitable to study the growth direction dependence of the subband dispersions. The axial approximation almost gives rise to the accurate low-energy subband dispersions for high-symmetry nanowire growth directions [001] and [111]. The perturbation correction from the non-axial term is negligible for these two directions. The lowest two subband dispersions can be regarded as two shifted parabolic curves with an energy gap at $k_{z}=0$ for both growth directions [001] and [111]. At the position of the energy gap, the eigenstates for growth direction [111] are inverted in comparison with the normal eigenstates for growth direction [001]. A nanowire growth direction where the energy gap closes at $k_{z}=0$ is predicted to exist between directions [001] and [111].