Gate controlled unitary operation on flying spin qubits in quantum Hall edge states

TL;DR

This paper demonstrates electrically controlled unitary operations on electron spins in quantum Hall edge states, enabling manipulation of spin qubits through gate voltages without magnetic fields, advancing quantum information processing.

Contribution

It introduces the first systematic electric control of spin rotations in quantum Hall edge channels using gate voltages to manipulate orbital parameters.

Findings

Controlled the zenith angle via gate voltage at a corner.

Manipulated the azimuth angle through edge channel distance.

Achieved systematic electric spin operations in quantum Hall edge states.

Abstract

Spin and orbital freedoms of electrons traveling on spin-resolved quantum Hall edge states (quantum Hall ferromagnets) are maximally entangled. The unitary operations on these two freedoms are hence equivalent, which means one can manipulate the spins with non-magnetic methods through the orbitals. If one takes the quantization axis of spins along the magnetization axis, the zenith angle is determined by the partition rate of spin-separated edges while the azimuth angle is defined as the phase difference between the edges. Utilizing these properties, we have realized electrically controlled unitary operation on the electron spins on the quantum Hall ferromagnets. The zenith angle of the spin was controlled through the radius of gyration at a corner by means of applying voltage to a thin gate placed at one edge. The subsequent rotation in the azimuth angle was controlled via the distance between the edge channels also by a gate voltage. The combination of the two operations constitutes the first systematic electric operation on spins in the quantum Hall edge channels.