Two-Photon Quantum Interference in Colloidal Lead-Halide Perovskite Quantum Dots

Chemically prepared colloidal semiconductor quantum dots have long been proposed as scalable and color-tunable single emitters in quantum optics, but they have typically suffered from prohibitively incoherent emission. Recent work has demonstrated the remarkable properties of individual lead-halide perovskite quantum dots (PQDs), which show remarkably coherent optical emission at low temperatures [1]. I highlight the latest developments of perovskite quantum emitters, including our first demonstration of two-photon (Hong-Ou-Mandel) interference of sequentially emitted single photons. We achieve visibilities of up to 0.55, above the limit for genuine quantum interference, even without cavity acceleration of the emission, indicating that entangled-photon generation is indeed possible with perovskites.[2] Our results highlight the potential of perovskite quantum dots as versatile, colloidal sources of coherent, indistinguishable single photons, that can further be engineered to emit circularly-polarized light with high efficiency and degree of polarization to open new avenues in chiral quantum optics.<br/> <br/>[1] Utzat et al. <i>Science</i>, <b>2019</b>, 363 (6431), 1068-1072.<br/>[2] (Utzat, Bawendi), <i>Nat. Photon., </i><b>2023</b>, <b>17</b>, 775–780.