Controllable photonic time-bin qubits from a quantum dot

TL;DR

This paper demonstrates deterministic control of photonic time-bin qubits generated from a quantum dot, enabling phase manipulation and wavelength multiplexing, which are promising for quantum communication.

Contribution

It introduces a method for complete phase control of time-bin qubits from a quantum dot, including wavelength division multiplexing at the single-photon level.

Findings

Complete phase control over time-bin qubits achieved

Deterministic photon generation with moderate coherence loss

Wavelength multiplexing demonstrated at the single-photon level

Abstract

Photonic time bin qubits are well suited to transmission via optical fibres and waveguide circuits. The states take the form $\frac{1}{\sqrt{2}}(\alpha \ket{0} + e^{i\phi}\beta \ket{1})$, with $\ket{0}$ and $\ket{1}$ referring to the early and late time bin respectively. By controlling the phase of a laser driving a spin-flip Raman transition in a single-hole-charged InAs quantum dot we demonstrate complete control over the phase, $\phi$. We show that this photon generation process can be performed deterministically, with only a moderate loss in coherence. Finally, we encode different qubits in different energies of the Raman scattered light, demonstrating wavelength division multiplexing at the single photon level.