Two-photon interference using background-free quantum frequency conversion of single photons from a semiconductor quantum dot

TL;DR

This paper demonstrates that quantum frequency conversion can effectively make photons from different solid-state quantum emitters indistinguishable, enabling high-visibility two-photon interference for quantum information applications.

Contribution

It introduces a background-free quantum frequency conversion method that preserves photon properties and enables interference of photons from different quantum dot transitions.

Findings

Achieved high signal-to-background ratio (>100:1) in frequency conversion.

Confirmed preservation of single-photon and wavepacket interference properties.

Demonstrated non-classical two-photon interference from spectrally separated quantum dot transitions.

Abstract

We show that quantum frequency conversion (QFC) can overcome the spectral distinguishability common to inhomogeneously broadened solid-state quantum emitters. QFC is implemented by combining single photons from an InAs quantum dot (QD) at 980 nm with a 1550 nm pump laser in a periodically-poled lithium niobate (PPLN) waveguide to generate photons at 600 nm with a signal-to-background ratio exceeding 100:1. Photon correlation and two-photon interference measurements confirm that both the single photon character and wavepacket interference of individual QD states are preserved during frequency conversion. Finally, we convert two spectrally separate QD transitions to the same wavelength in a single PPLN waveguide and show that the resulting field exhibits non-classical two-photon interference.