Hole spins in quantum wires and quantum dots

The spin states of heavy holes in semiconductor nanostructures are attracting significant attention for quantum information applications, with rapid progress being made by a number of groups over the past few years. In this talk I will discuss our recent progress studying spin properties of holes in silicon and gallium arsenide quantum wires and dots. In GaAs hole quantum wires we observe highly anisotropic spin properties, which can be used to directly probe the spin-orbit interaction in holes [1.2], as well as evidence for an emergeny spin gap. In silicon single quantum dots we are able to study the spin shell filling sequence for the first 8 holes, which is consistent with the Fock-Darwin states of a circular 2D quantum dot. However while the spin filling obeys Hund’s first rule, the hole-hole interaction energy is 90% of the orbital energy [3]. In few hole GaAs and Si double quantum dots we observe Pauli spin blockade, and find that the lifting of the spin blockade by an external magnetic field is highly anisotropic. These results highlight the promise, and challenges, of using holes for spin qubits.

[1] D. S. Miserev, A. Srinivasan, O. A. Tkachenko, V. A. Tkachenko, I. Farrer, D. A. Ritchie, A. R. Hamilton, and O. P. Sushkov, “Mechanisms for Strong Anisotropy of In-Plane g -Factors in Hole Based Quantum Point Contacts,” Physical Review Letters 119 (2017).
[2] A. Srinivasan, D. S. Miserev, K. L. Hudson, O. Klochan, K. Muraki, Y. Hirayama, D. Reuter, A. D. Wieck, O. P. Sushkov, et al., “Detection and Control of Spin-Orbit Interactions in a GaAs Hole Quantum Point Contact,” Physical Review Letters 118 (2017).
[3] S. D. Liles, R. Li, C. H. Yang, F. E. Hudson, M. Veldhorst, A. S. Dzurak, and A. R. Hamilton, “Spin and orbital structure of the first six holes in a silicon metal-oxide-semiconductor quantum dot,” Nature Communications 9 (2018).