Shell structure and spin filling of the first six holes in a silicon MOS quantum dot

Heavy hole spins in quantum dots are promising candidates for spin qubits. This is because holes have reduced hyperfine coupling to nuclear spins, allowing long spin coherence times [1], while the enhanced spin-orbit coupling of holes enables fast all-electric spin manipulation via EDSR [2]. However, challenges in device fabrication and complexities in theory have limited the number of studies using hole-based devices. In this talk we discuss our recent progress in silicon-based hole quantum dots. We describe a planar silicon metal-oxide-semiconductor (MOS) based single hole quantum dot and demonstrate operation down to the last hole. We then characterise the spin shell filling sequence and orbital structure for the first six holes using magneto-spectroscopy and pulse-bias spectroscopy. These results suggest that two-hole system is on the verge of having a ferromagnetic ground state, which is of interest to spin qubit applications since spin-to-charge operations are typically performed using the two charge, (0,2) to (1,1), configuration.

1. D. V. Bulaev, and D. Loss, PRL 95 (2005)
2. D. V. Bulaev, and D. Loss, PRL 98 (2007)