Double-occupancy probability and entanglement of two holes in double Ge/Si quantum dots

A. I. Yakimov, A. A. Bloshkin, A. V. Dvurechenskii

*Rzhanov Institute of Semiconductor Physics, Siberian Branch RAS*

630090 Novosibirsk, Russia

**Abstract**

We have calculated the exchange energy, double
occupation probability of the lowest singlet state, and degree of
entanglement of two holes in vertically coupled double Ge/Si
quantum dots. We determined the conditions on which the exchange
coupling is large enough for a fast swap operation in quantum
computation and the double-occupancy probability is still low,
thus maximizing the entanglement for a small computation error. We
found that both the degree of entanglement and double-occupancy
probability for quantum dots with different dot size collapse
onto universal, size independent curves when plotted as a function
of singlet-triplet splitting.