Control of valley dynamics in silicon quantum dots in the presence of an interface step

Péter Boross, Gábor Széchenyi, Dimitrie Culcer, and András Pályi
Phys. Rev. B 94, 035438 – Published 22 July 2016

Abstract

Recent experiments on silicon nanostructures have seen breakthroughs toward scalable, long-lived quantum information processing. The valley degree of freedom plays a fundamental role in these devices, and the two lowest-energy electronic states of a silicon quantum dot can form a valley qubit. In this paper, we show that a single-atom high step at the silicon/barrier interface induces a strong interaction of the qubit and in-plane electric fields and that the strength of this interaction can be controlled by varying the relative position of the electron and the step. We analyze the consequences of this enhanced interaction on the dynamics of the qubit. The charge densities of the qubit states are deformed differently by the interface step, allowing nondemolition qubit readout via valley-to-charge conversion. A gate-induced in-plane electric field together with the interface step enables fast control of the valley qubit via electrically driven valley resonance. We calculate single- and two-qubit gate times, as well as relaxation and dephasing times, and present predictions for the parameter range where the gate times can be much shorter than the relaxation time and dephasing is reduced.

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  • Received 25 April 2016
  • Revised 2 July 2016

DOI:https://doi.org/10.1103/PhysRevB.94.035438

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Péter Boross1, Gábor Széchenyi1, Dimitrie Culcer2, and András Pályi1,3

  • 1Institute of Physics, Eötvös University, Budapest, Hungary
  • 2School of Physics, The University of New South Wales, Sydney 2052, Australia
  • 3Department of Physics and MTA-BME Condensed Matter Research Group, Budapest University of Technology and Economics, Budapest, Hungary

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Issue

Vol. 94, Iss. 3 — 15 July 2016

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