Spin decoherence of a heavy hole coupled to nuclear spins in a quantum dot

Abstract

We theoretically study the interaction of a heavy hole with nuclear spins in a quasi-twodimensional III-V semiconductor quantum dot and the resulting dephasing of heavy-hole spin states. It has frequently been stated in the literature that heavy holes have a negligible interaction with nuclear spins. We show that this is not the case. In contrast, the interaction can be rather strong and will be the dominant source of decoherence in some cases. We also show that for unstrained quantum dots the form of the interaction is Ising-like, resulting in unique and interesting decoherence properties, which might provide a crucial advantage to using dot-confined hole spins for quantum information processing, as compared to electron spins.

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

“…The hole properties are traced to the amount of HH-LH subband mixing [12,13], which is related to the details of quantum confinement, strain, and the spin-orbit interaction. The early prediction of greatly reduced hyperfine interaction between hole and nuclear spins, and concomitant increased coherence times [14,15], were confirmed experimentally in systems with small HH-LH mixing realized as selfassembled dots (SADs) [16][17][18] or nanowires [19]. In this regime the strong anisotropy of the hole g-factor is expected [12].…”

Hole-spin initialization and relaxation times in InAs/GaAs quantum dots

“…The hf interaction has been identified as the dominant electron-and hole-spin dephasing source at weak or zero magnetic field and low temperature in QDs, [18][19][20][21][22][23][24][25] leading to a dephasing time in the order of nanoseconds or tens of nanoseconds. Unlike electrons for which the contact term is the predominant contribution of the hf interaction, holes couple more weakly to nuclear spins via the anisotropic dipoledipole term of the hf interaction.…”

“…Unlike electrons for which the contact term is the predominant contribution of the hf interaction, holes couple more weakly to nuclear spins via the anisotropic dipoledipole term of the hf interaction. 24,25 Recently, the relative strength of the electron-nuclear coupling to the hole-nuclear coupling has been measured to be of the order of ten. [26][27][28] Meanwhile, when the effect of the nuclear dipole-dipole interaction is neglected, 29 theoretical works predict for both carriers two-time scales in the spin dynamics imposed by the hf interaction.…”

Towards coherent optical control of a single hole spin: Rabi rotation of a trion conditional on the spin state of the hole

“…Since the wavefunction of the heavy-hole has a p-type Bloch-function, the contact hyperfine interaction is zero, and hence the nuclear spin dephasing should be much weaker for holes [45]. Although recently Fischer et al [46] have pointed out that the hole is not entirely immune to the effects of nuclear spin. At the moment it is not clear if electron or hole spins will make better q-bits, but in principle, one could apply the same ideas to a p-type Schottky diode to prepare, and detect a single electron spin.…”