Abstract
Nuclear spin registers in the vicinity of electron spins in solid state systems offer a powerful resource to address the challenge of scalability in quantum architectures. We investigate here the properties of 29Si nuclear spins surrounding donor atoms in silicon, and consider the use of such spins, combined with the donor nuclear spin, as a quantum register coupled to the donor electron spin. We find the coherence of the nearby 29Si nuclear spins is effectively protected by the presence of the donor electron spin, leading to coherence times in the second timescale—over two orders of magnitude greater than the coherence times in bulk silicon. We theoretically investigate the use of such a register for quantum error correction (QEC), including methods to protect nuclear spins from the ionisation/neutralisation of the donor, which is necessary for the re-initialisation of the ancillae qubits. This provides a route for multi-round QEC using donors in silicon.
Highlights
Our focus here is on Naturally occurring silicon (natSi), and in particular the 29Si nuclear spins around the donor
Nuclear spin coherence times of 29Si have been studied in the absence of the donor electron — in such cases the nuclear spins can freely flip-flop and the Hahn echo T2n is limited to around 5 ms
One could expect the T2n of 29Si in the vicinity of the donor to be significantly longer — an indication of this is in the T2n of the donor nuclear spin itself which was reported to be about 1 second in natSi [20]
Summary
Our focus here is on natSi, and in particular the 29Si nuclear spins around the donor. A comparable coherence time of 1.22 ± 0.03 s was measured for a 29Si nuclear spin with hyperfine coupling A = 4.03 MHz (Fig. 2(c)), notably over 200 times longer than in bulk natural silicon.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
