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arXiv:2412.15762 · Nano Letters

Indistinguishability of Remote Quantum-Dot-Cavity Single-Photon Sources

Mathias Pont, Stephen C. Wein, Ilse Maillette de Buy Wenniger, Valentin Guichard, Nathan Coste, Abdelmounaïm Harouri, Aristide Lemaître, Isabelle Sagnes, L. Lanco, Nadia Belabas, Niccolò Somaschi, Sarah E. Thomas, P. Senellart

Published Sep 11, 2025• 3 citations
arXivHTMLPDF

Abstract

Generating identical photons from remote emitter-based bright single-photon sources is an important step for scaling up optical quantum technologies. Here, we study the Hong-Ou-Mandel interference of photons emitted from remote sources based on semiconductor quantum dots (QDs). We make use of a deterministic fabrication technique to position the QDs in a spectrally resonant micropillar cavity and fine-tune their operation wavelength electrically. In doing so, we can match four pairs of sources between five distinct sources, study them under various excitation schemes, and measure their degree of indistinguishability. We demonstrate remote indistinguishabiltity between 44 ± 1% and 69 ± 1% depending on the pair of sources and excitation conditions, record values for QDs in cavities. The relative contribution of pure dephasing and spectral diffusion is then analyzed, revealing that the remaining distinguishability is mostly due to low-frequency noise.

DOI
10.1021/acs.nanolett.5c01560

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Generating identical photons from remote emitter-based bright single-photon sources is an important step for scaling up optical quantum technologies. Here, we study the Hong-Ou-Mandel interference of photons emitted from remote sources based on semiconductor quantum dots (QDs). We make use of a deterministic fabrication technique to position the QDs in a spectrally resonant micropillar cavity and fine-tune their operation wavelength electrically. In doing so, we can match four pairs of sources between five distinct sources, study them under various excitation schemes, and measure their degree of indistinguishability. We demonstrate remote indistinguishabiltity between 44 ± 1% and 69 ± 1% depending on the pair of sources and excitation conditions, record values for QDs in cavities. The relative contribution of pure dephasing and spectral diffusion is then analyzed, revealing that the remaining distinguishability is mostly due to low-frequency noise.
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Quantum interference of indistinguishable photons is the foundation of photonic quantum technologies, yet scaling from a few to many identical quantum light sources remains a major challenge. In solid-state platforms, spatial and spectral inhomogeneity and resource-intensive architectures impede scaling. As a result, interference between remote, independent quantum emitters has been thus far limited to pairs. Here we introduce a wavefront-shaping approach that enables scalable interference from multiple indistinguishable quantum dots on the same chip. Using programmable spatial light modulators, we independently excite, collect, and route emission from spatially distinct, yet spectrally degenerate dots. Scaling from two to five indistinguishable emitters, we verify interference through cooperative-emission phenomena and Hong-Ou-Mandel two-photon interference, thereby establishing a route towards large-scale, programmable quantum photonic architectures.
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Quantum dots in cavities have been shown to be very bright sources of indistinguishable single photons. Yet the quantum interference between two such bright quantum dot sources, a critical step for photon-based quantum computation, still needs to be investigated. Here, we report on such a measurement, taking advantage of a deterministic fabrication of the devices. We show that cavity quantum electrodynamics can efficiently improve the quantum interference between remote quantum dot sources: Poorly indistinguishable photons can still interfere with good contrast with high quality photons emitted by a source in the strong Purcell regime. Our measurements and calculations show that cavity quantum electrodynamics is a powerful tool for interconnecting several quantum dot devices.
We report on two-photon interference (TPI) experiments using remote deterministic single-photon sources. Employing 3D in-situ electron-beam lithography, we fabricate quantum-light sources at specific target wavelengths by integrating pre-selected semiconductor quantum dots within monolithic microlenses. The individual single-photon sources show TPI visibilities of 49% and 22%, respectively, under pulsed p-shell excitation at 80 MHz. For the mutual TPI of the remote sources, we observe an uncorrected visibility of 29%, in quantitative agreement with the pure dephasing of the individual sources. Due to its efficient photon extraction within a broad spectral range (>20 nm), our microlens-based approach is predestinated for future entanglement swapping experiments utilizing entangled photon pairs emitted by distant biexciton-exciton radiative cascades.