Dynamic strain modulation of a nanowire quantum dot compatible with a thin-film lithium niobate photonic platform

TL;DR

This paper demonstrates dynamic strain tuning of nanowire quantum dot single photon sources integrated with a thin-film lithium niobate platform, preserving photon purity and enabling on-chip quantum photonic applications.

Contribution

It introduces a novel method for strain modulation of nanowire quantum dots on lithium niobate, compatible with integrated photonic circuits, using surface acoustic waves.

Findings

Strain tuning preserves single photon purity.

Acousto-optical coupling enables dynamic emission control.

Device architecture integrates quantum dots with lithium niobate waveguides.

Abstract

The integration of on-demand single photon sources in photonic circuits is a major prerequisite for on-chip quantum applications. Among the various high-quality sources, nanowire quantum dots can be efficiently coupled to optical waveguides because of their preferred emission direction along their growth direction. However, local tuning of the emission properties remains challenging. In this work, we transfer a nanowire quantum dot on a bulk lithium niobate substrate and show that its emission can be dynamically tuned by acousto-optical coupling with surface acoustic waves. The purity of the single photon source is preserved during the strain modulation. We further demonstrate that the transduction is maintained even with a SiO2 encapsulation layer deposited on top of the nanowire acting as the cladding of a photonic circuit. Based on these experimental findings and numerical simulations, we introduce a device architecture consisting of a nanowire quantum dot efficiently coupled to a thin film lithium niobate rib waveguide and strain-tunable by surface acoustic waves.