Violation of local realism with spatially multimode parametric down-conversion pumped by spatially incoherent light
Abstract
We experimentally demonstrate a violation of local realism with highly spatially multimode polarization-entangled two-photon states produced by spontaneous parametric down-conversion (SPDC) pumped by a spatially incoherent light source-a light-emitting diode (LED). While existing studies have observed such a violation only by post-selecting the LED-pumped SPDC photons into a single spatial detection mode, we achieve a Clauser-Horne-Shimony-Holt inequality violation of S = 2.532 0.069 > 2 using a spatially multimode detection setup that collects nearly 4,080 SPDC spatial modes. These results indicate that coherent pump sources, such as lasers, are not required for SPDC-based entanglement generation. Our work could enable novel and practical sources of entangled photons for quantum technologies such as device-independent quantum key distribution and quantum-enhanced sensing.
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