skip to main content

SciTech ConnectSciTech Connect

Title: Charge noise, spin-orbit coupling, and dephasing of single-spin qubits

Quantum dot quantum computing architectures rely on systems in which inversion symmetry is broken, and spin-orbit coupling is present, causing even single-spin qubits to be susceptible to charge noise. We derive an effective Hamiltonian for the combined action of noise and spin-orbit coupling on a single-spin qubit, identify the mechanisms behind dephasing, and estimate the free induction decay dephasing times T{sub 2}{sup *} for common materials such as Si and GaAs. Dephasing is driven by noise matrix elements that cause relative fluctuations between orbital levels, which are dominated by screened whole charge defects and unscreened dipole defects in the substrate. Dephasing times T{sub 2}{sup *} differ markedly between materials and can be enhanced by increasing gate fields, choosing materials with weak spin-orbit, making dots narrower, or using accumulation dots.
Authors:
; ;  [1]
  1. School of Physics, The University of New South Wales, Sydney 2052 (Australia)
Publication Date:
OSTI Identifier:
22391948
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 19; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CRYSTAL DEFECTS; GALLIUM ARSENIDES; HAMILTONIANS; L-S COUPLING; MATRIX ELEMENTS; NOISE; QUANTUM COMPUTERS; QUANTUM DOTS; QUBITS; SILICON; SPIN; SYMMETRY BREAKING