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arXiv:2606.31775 · Nanoscale

Energy–time entanglement from a monolithically integrated quantum dot on silicon

Marcel Hohn, Imad Limame, Peter Ludewig, Chirag C. Palekar, Aris Koulas‐Simos, Kerstin Volz, Stephan Reitzenstein

Published Jan 1, 2026• 0 citations

Abstract

Scalable quantum photonic technologies require deterministic sources of entangled photons that are compatible with established semiconductor manufacturing platforms. While self-assembled III-V semiconductor quantum dots are among the most promising sources of on-demand entanglement generation, their integration with silicon-based architectures remains a central challenge. Here, we demonstrate energy-time entanglement from a single InGaAs/GaAs quantum dot monolithically grown on a silicon substrate. Under resonant two-photon excitation, we achieve coherent control of the biexciton-exciton cascade, evidenced by the formation of dressed-states and Rabi oscillations. Using a four-channel Franson interferometer, we observe phase-dependent two-photon interference with visibilities up to (64.0 ± 7.0)% for a 80 ps integration window (and (49.4 ± 1.9)% for a 1600 ps window), approaching the threshold for Bell inequality violation at short timescales. Despite these constraints, the observation of Franson interference establishes monolithic III-V-on-silicon quantum dots as viable sources of energy-time entangled photons. These results represent a crucial step toward fully integrated, silicon-substrate-compatible quantum photonic circuits for large-scale quantum communication and information processing.

DOI: 10.1039/d6nr02565j

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Entanglement is a major resource in advanced quantum technology, where it can enable secure exchange of information over large distances. Energy-time entanglement is particularly attractive for its beneficial robustness in fiber-based quantum communication and can be demonstrated in the Franson interferometer. We report on Franson-type interference from a resonantly driven biexciton cascade under continuous wave excitation. Our measurements yield a maximum visibility of (73

\pm

2)% surpassing the limit of violation of Bell's inequality (70.7%) by more than one standard deviation. Despite being unable to satisfy a loophole free violation, our work demonstrates promising results concerning future works on such a system. Furthermore, our systematical studies on the impact of driving strength indicate that dephasing mechanisms and deviations from the cascaded emission have major impact on the degree of the measured energy-time entanglement.

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