An ultra-compact deterministic source of maximally entangled photon pairs

M. Langer; P. Ruchka; A. Rahimi; S. Jakovljevic; Y. G. Zena; A. Danilov; M. Pal; R. Bassoli; F. H. P. Fitzek; O. G. Schmidt; H. Giessen; C. Hopfmann

arXiv · 2502.11623

An ultra-compact deterministic source of maximally entangled photon pairs

M. Langer·P. Ruchka·A. Rahimi·S. Jakovljevic·Y. G. Zena·A. Danilov·M. Pal·R. Bassoli·F. H. P. Fitzek·O. G. Schmidt·H. Giessen·C. Hopfmann

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Abstract

We present an ultra-compact source of maximally entangled on-demand photon pairs. Our results are based on coupling of single GaAs quantum dots that are embedded in monolithic micro-lenses to a single-mode fiber with directly attached to 3D-printed micro-optics (NA of 0.6) inside a cryogenic environment. This approach, which is geared towards future integration into industrial environments, yields state-of-the-art entangled photon pair creation performance while retaining flexibility and adjustability required for long-term operation of such a device - all while dramatically reducing the overall system footprint. We demonstrate near diffraction-limited performance and hyperspectral imaging utilizing a 3D-printed micro-objective with a full width at half maximum resolution limit of 604(16) nm when operating the system at a cryogenic temperature of 3.8 K. Furthermore, we prove that this system can be used to achieve single photon emission rates of 392(20) kHz at a 76 MHz pump rate and purities of 99.2(5) % using two-photon resonant excitation. Utilizing the exciton-biexciton emission cascade available in GaAs quantum dots under resonant excitation, near maximally entangled photon pairs with peak entanglement negatives 2n of 0.96(2) in a 4 ps time window, and 0.81(1) when averaged over one exciton lifetime, are demonstrated.

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M. Langer, P. Ruchka, A. Rahimi, S. Jakovljevic, Y. G. Zena, A. Danilov, M. Pal, R. Bassoli, F. H. P. Fitzek, O. G. Schmidt, H. Giessen, C. Hopfmann. 2025-03-11. An ultra-compact deterministic source of maximally entangled photon pairs. https://arxiv.org/abs/2502.11623

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