A device for achieving multi-
photon interference, said device comprising: at least two
solid state
photon emitters, each
solid state
photon emitter comprising nuclear and
electron spin states coupled together, each
solid state photon emitter being configured to produce
photon emission comprising a
photon emission peak, wherein the
photon emission peaks from different
solid state photon emitters have a first
frequency difference between peak intensities, and wherein the
electron spin states of each
solid state photon emitter are resolvable; an excitation arrangement configured to individually address the at least two
solid state photon emitters; a plurality of optical out
coupling structures wherein each solid state photon emitter is provided with an associated optical out
coupling structure; a tuning arrangement configured to reduce the first
frequency difference between the peak intensities of the photon emission peaks from the at least two solid state photon emitters to a second
frequency difference which is smaller than the first frequency difference; a photon interference arrangement configured to overlap photon emissions from the at least two solid state emitters after tuning; and a
detector arrangement configured to detect photon emissions from the at least two solid state emitters after tuning and passing through the photon interference arrangement, wherein the
detector arrangement is configured to resolve sufficiently small differences in
photon detection times that tuned photon emissions from the at least two solid state emitters are
quantum mechanically indistinguishable resulting in
quantum interference between indistinguishable photon emissions from different solid state photon emitters.