Entangled ripples and twists of light: Radial and azimuthal\n Laguerre-Gaussian mode entanglement Article Swipe
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· 2021
· Open Access
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· DOI: https://doi.org/10.1088/2040-8986/ac213c
· OA: W3195934163
It is well known that photons can carry a spatial structure akin to a\n"twisted" or "rippled" wavefront. Such structured light fields have sparked\nsignificant interest in both classical and quantum physics, with applications\nranging from dense communications to light-matter interaction. Harnessing the\nfull advantage of transverse spatial photonic encoding using the\nLaguerre-Gaussian (LG) basis in the quantum domain requires control over both\nthe azimuthal (twisted) and radial (rippled) components of photons. However,\nprecise measurement of the radial photonic degree-of-freedom has proven to be\nexperimentally challenging primarily due to its transverse amplitude structure.\nHere we demonstrate the generation and certification of full-field\nLaguerre-Gaussian entanglement between photons pairs generated by spontaneous\nparametric down-conversion in the telecom regime. By precisely tuning the\noptical system parameters for state generation and collection, and adopting\nrecently developed techniques for precise spatial mode measurement, we are able\nto certify fidelities up to 85% and entanglement dimensionalities up to 26 in a\n43-dimensional radial and azimuthal LG mode space. Furthermore, we study\ntwo-photon quantum correlations between 9 LG mode groups, demonstrating a\ncorrelation structure related to mode group order and inter-modal cross-talk.\nIn addition, we show how the noise-robustness of high-dimensional entanglement\ncertification can be significantly increased by using measurements in multiple\nLG mutually unbiased bases. Our work demonstrates the potential offered by the\nfull spatial structure of the two-photon field for enhancing technologies for\nquantum information processing and communication.\n
