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.Comment: 8 pages, 5 figure