The interference of non-classical states of light enables quantum-enhanced applications reaching from metrology to computation. Most commonly, the polarisation or spatial location of single photons are used as addressable degrees-of-freedom for turning these applications into praxis. However, the scale-up for the processing of a large number of photons of such architectures is very resource demanding due to the rapidily increasing number of components, such as optical elements, photon sources and detectors. Here we demonstrate a resource-efficient architecture for multi-photon processing based on time-bin encoding in a single spatial mode. We employ an efficient quantum dot single-photon source, and a fast programmable time-bin interferometer, to observe the interference of up to 8 photons in 16 modes, all recorded only with one detector--thus considerably reducing the physical overhead previously needed for achieving equivalent tasks. Our results can form the basis for a future universal photonics quantum processor operating in a single spatial mode.
@article{arxiv.2305.11157,
title = {Programmable multi-photon quantum interference in a single spatial mode},
author = {Lorenzo Carosini and Virginia Oddi and Francesco Giorgino and Lena M. Hansen and Benoit Seron and Simone Piacentini and Tobias Guggemos and Iris Agresti and Juan Carlos Loredo and Philip Walther},
journal= {arXiv preprint arXiv:2305.11157},
year = {2024}
}