Four photons now interfere with high efficiency, a quantum dot first

Researchers at the University of Sheffield and University of Basel have, for the first time, demonstrated quantum interference using up to four photons emitted from a single quantum dot. The team overcame longstanding efficiency limitations by combining a quantum dot with a technique called deterministic demultiplexing, directly observing quantum interference fringes. Measurements reveal high interference contrasts of 93.0 ± 0.1% for two photons and 84.1 ± 1.0% for four, with the results predicting similar interference patterns will extend to even larger numbers of photons and potentially enhance quantum metrology. Deterministic demultiplexing, paired with a quantum dot, enabled the direct observation of quantum interference fringes originating from up to four photons, a feat previously limited by efficiency constraints in scaling quantum dot-based interference. The team’s approach allows for the manipulation of larger photonic states, essential for…