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A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Twin-Twisted van der Waals Crystal for Entangled Photon Source
Chaojie Ma1,2, Mingkang Zhang1, Lu He3
1Peking University, State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Beijing, China.
Abstract:
Bright entangled photon sources with on-demand quantum state control are essential for advancing quantum science and technologies. However, simultaneously achieving high brightness and state tunability remains challenging, as this necessitates a dual-phase control mechanism that facilitates both longitudinal phase matching and transverse polarization modulation. Here, we report a twin-twisted two-dimensional (2D) van der Waals (vdW) crystal architecture that enables spontaneous parametric down-conversion (SPDC) with both high generation efficiency and continuously tunable quantum states. The designed crystal comprises two sections of twisted 2D GaSe vdW flakes with opposite chiral handedness, in which interflake twist angle induces phase matching in SPDC, and intersection twisting provides an additional degree of freedom on tunability. We demonstrate that the twin-twisted GaSe crystals achieve a record-high photon-pair generation rate exceeding 13 200 Hz and a Bell state fidelity above 99% within 2D material family, and enable unprecedented tunability of quantum states from the maximally polarization entangled states to the fully separable states. This study opens a practical avenue toward twist-engineered quantum states, and paves the way for developing compact quantum photonic systems with tailored properties.
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