Extended quantum networks are based on quantum repeaters that often rely on the distribution of entanglement in an efficient and heralded fashion over multiple network nodes. Many repeater architectures require multiplexed sources of entangled photon pairs, multiplexed quantum memories, and photon detection that distinguishes between the multiplexed modes.
Scientists have demonstrated the concurrent employment of (1) spectrally multiplexed cavity-enhanced spontaneous parametric down-conversion in a nonlinear crystal; (2) a virtually-imaged phased array that enables mapping of spectral modes onto distinct spatial modes for frequency-selective detection; and (3) a cryogenically-cooled Tm3+:LiNbO3crystal that allows spectral filtering in an approach that anticipates its use as a spectrally-multiplexed quantum memory.
Through coincidence measurements, we demonstrate quantum correlations between energy-correlated photon pairs and a strong reduction of the correlation strength between all other photons.
This constitutes an important step towards a frequency-multiplexed quantum repeater.
npj Quantum Information, Published online: 10 January 2025; doi:10.1038/s41534-024-00946-2
