Measuring non-classical statistics of fluorescence from a single atom on atom array towards quantum networking*

Atom arrays are a promising platform for quantum processing by leveraging the long coherence time, the ability to integrate qubits, and the flexibility of qubit geometry. It is expected that further scaling up by connecting remote atom arrays via photonic interfaces enables high-performance quantum processing. Such investigations have been actively caried out both theoretically and experimentally based on free-space optics, cavities and nano photonics, while collecting entangled photons emitted from single atoms in an atom array remains challenging. In this talk, we will report on our progress of building an atom array system which allows us to retrieve photons from single atoms by coupling them to single-mode optical fiber through free-space optics.

In the experiment, the optical tweezers for implementing our ⁸⁷Rb atom array were formed by using 852 nm light, and the trap lifetime of a few tens of seconds was achieved. We made the single atom emit fluorescence by imposing cooling and repumping light for MOT. The fluorescence was collected through an objective lens with NA=0.7, and coupled to an optical fiber that was connected to Hanbury-Brown Twiss setup. The auto-correlation function was measured by photon counts with post-selecting the existence of a single atom on the target site. The obtained value was , which proves non-classical statistics of a single photon.