Hyperfine-assisted fast electric control of dopant nuclear spins in semiconductors

Abstract

Nuclear spins of dopant atoms in semiconductors are promising candidates as quantum bits, due to the long lifetime of their quantum states. Conventionally, coherent control of nuclear spins is done using ac magnetic fields. Using the example of a phosphorus atom in silicon, we theoretically demonstrate that hyperfine interaction can enhance the speed of magnetic control: the electron on the donor amplifies the ac magnetic field felt by the nuclear spin. Based on that result, we show that hyperfine interaction also provides a means to control the nuclear spin efficiently using an ac electric field, in the presence of intrinsic or artificial spin-orbit interaction. This electric control scheme is especially efficient and noise-resilient in a hybrid dot-donor system holding two electrons in the presence of an inhomogeneous magnetic field. The mechanisms proposed here could be used as building blocks in nuclear-spin-based electronic quantum information architectures.

Hyperfine-assisted decoherence of a phosphorus nuclear-spin qubit in silicon

“…This mechanism was implicitly quantified already in Eq. In contrast to the 1e setup showing poor coherence properties, much improvement is anticipated for the 2e setup 13 . Importantly, silicon-based dot-donor devices holding an even number of electrons are available experimentally 21,32 .…”

“…In this section, we introduce the P:Si nuclearspin qubit and the special dot-donor setup that enables its electrical control. We discuss two different arrangements: 13 . Single-electron setup (1e): A single electron is confined in the dot-donor system.…”

“…For a particular parameter set studied in Ref. 13, the energy eigenstates of H are shown as the function of the on-site energy difference U in Fig. 1b.…”

“…(A2b) of Ref. 13. Following the 1e case, it is useful to introduce the antibonding and bonding singlet energy eigenstates of H ch , i.e., the molecular states formed by |S and |S 02 , which we will denote as |S a and |S b , respectively.…”

“…To ensure that the nuclear-spin qubit dynamics upon electrical drive follows regular and fast Rabi oscillations 13 , it is reasonable to set the value of δ much larger than the coupling matrix element induced by the inhomogeneous magnetic field between the electronic states |S b and |T − . This relation is satisfied, e.g., with the choice δ = 200 S b |H µ,e |T − .…”