Probing a single nuclear spin in a silicon single electron transistor

Abstract

We study single electron transport across a single Bi dopant in a Silicon Nanotransistor to assess how the strong hyperfine coupling with the Bi nuclear spin I = 9/2 affects the transport characteristics of the device. In the sequential tunneling regime we find that at, temperatures in the range of 100mK, dI/dV curves reflect the zero field hyperfine splitting as well as its evolution under an applied magnetic field. Our non-equilibrium quantum simulations show that nuclear spins can be partially polarized parallel or antiparallel to the electronic spin just tuning the applied bias. PACS: 73.23.Hk, 31.30.Gs, 74.55.+v, The amazing progress both in the silicon processing technologies and in the miniaturization of silicon based transistors has reached the point where singledopant transistors have been demonstrated.1-7 Whereas this progress has been fueled by the development of classical computing architectures, it might also be used for quantum computing. In this regard, the electronic and nuclear spins of single donors in silicon are very promising building blocks for quantum computing.8-10 Progress along this direction makes it necessary to implement single spin readout schemes both for electronic and nuclear spins. Single electronic spin readout has been demonstrated, both in GaAs quantum dots as well as in P doped Silicon Nanotransistors. 11,12The readout of the quantum state of a single nuclear spin, much more challenging, has been demonstrated for NV centers in diamond taking advantage of single spin optically detected magnetic resonance afforded by the extraordinary properties of that system. 13 Single nuclear spin readout with either optical 14 or a combined electrooptical techniques 15 has been proposed, but remains to be implemented. Here we explore the electrical readout of a single nuclear spin, more suitable for an indirect band-gap host like Si. A preliminary step is to construct a circuit whose transport is affected by the quantum state of the nuclear spin. There is ample experimental evidence of the mutual influence of many nuclear spins and transport electrons in III-V semiconductor quantum dots in the single electron transport regime. [16][17][18][19] In particular, Kobayashi et al. have reported hysteresis in the dI/dV upon application of magnetic fields, reflecting the realization of different ensemble of nuclear states coupled to the electronic spin via hyperfine coupling. 19Here we propose a device where a single nuclear spin is probed in single electron transport. We model the single electron transport in a silicon nanotransistor such that, in the active region, transport takes place through a single Bi dopant, see Fig. 1. We show that, at sufficiently low temperatures, the dI/dV curves of this device probe the hyperfine structure of the dopant level. In turn, the occupations of the nuclear spin states are affected by the transport electrons. Whereas single dopant transistors have been demonstrated for single P, As and B, in Si, 3,4,6,12 we choose Bi because it has a much larger hyperfine spl...

Spin decoherence of magnetic atoms on surfaces

“…(3), H = H S + H R + V. In the case of magnetic adatoms, H S describes the atomic spins and usually accounts for the local magnetic anisotropy, inter-spin interactions, and Zeeman interactions. If required, one can also include the nuclear spins in the system degrees of freedom [128,129], in which case H S should include the hyperfine interactions as well. In the basis of eigenstates of H S , we can write H S = n E n |n n|.…”