Theory of semiconductor quantum-wire based single- and two-qubit gates

TL;DR

This paper proposes a GaAs/AlGaAs quantum device for single- and two-qubit operations, utilizing a novel Green's function method to predict entanglement control via electrical tuning in a complex quantum wire system.

Contribution

It introduces a new theoretical framework and concrete device designs for entanglement generation and control in semiconductor quantum wires and dots.

Findings

Entanglement can be controlled externally by tuning tunneling coupling.

Device designs enable straightforward detection of entanglement.

Non-perturbative calculations predict device behavior accurately.

Abstract

A GaAs/AlGaAs based two-qubit quantum device that allows the controlled generation and straightforward detection of entanglement by measuring a stationary current-voltage characteristic is proposed. We have developed a two-particle Green's function method of open systems and calculate the properties of three-dimensional interacting entangled systems non-perturbatively. We present concrete device designs and detailed, charge self-consistent predictions. One of the qubits is an all-electric Mach-Zehnder interferometer that consists of two electrostatically defined quantum wires with coupling windows, whereas the second qubit is an electrostatically defined double quantum dot located in a second two-dimensional electron gas beneath the quantum wires. We find that the entanglement of the device can be controlled externally by tuning the tunneling coupling between the two quantum dots.