Coherent rotations of a single spin-based qubit in a single quantum dot at fixed Zeeman energy

TL;DR

This paper demonstrates how to perform coherent rotations of a single spin qubit in a quantum dot by electrically tuning the dot's shape at fixed magnetic conditions, providing a precise control method for quantum computing.

Contribution

It introduces a method for electrically controlling a spin qubit within a single quantum dot by shape manipulation, with an exact analytic solution for Coulomb interactions.

Findings

Exact analytic solution for Coulomb matrix elements.

Range of pseudomagnetic field magnitudes and directions calculated.

Numerical estimates provided for GaAs quantum dots.

Abstract

Coherent rotations of single spin-based qubits may be accomplished electrically at fixed Zeeman energy with a qubit defined solely within a single electrostatically-defined quantum dot; the $g$-factor and the external magnetic field are kept constant. All that is required to be varied are the voltages on metallic gates which effectively change the shape of the elliptic quantum dot. The pseudospin-1/2 qubit is constructed from the two-dimensional $S=1/2$, $S_z=-1/2$ subspace of three interacting electrons in a two-dimensional potential well. Rotations are created by altering the direction of the pseudomagnetic field through changes in the shape of the confinement potential. By deriving an exact analytic solution to the long-range Coulomb interaction matrix elements, we calculate explicitly the range of magnitudes and directions the pseudomagnetic field can take. Numerical estimates are given for {GaAs}.