Hong-Ou-Mandel interference of more than 10 indistinguishable atoms

Abstract

When two indistinguishable bosons interfere at a beam splitter, they both exit through the same output port, a phenomenon known as the Hong-Ou-Mandel (HOM) effect. It extends to many indistinguishable particles (in two modes), providing a prime example for N-particle interference. vspace In photonic systems, losses typically challenge the direct observation. A realization with atomic systems has remained elusive until now, often due to detection noise obscuring single-particle signals. vspace Here, we demonstrate HOM interference with up to 12 indistinguishable neutral atoms in a spinor BEC, showing negligible loss. Our novel single-atom resolving fluorescence detection clearly reveals parity oscillations and a bunching envelope, two defining features of the multi- particle HOM effect. We confirm maximal entanglement in the generated Twin-Fock states using a novel criterion based on parity. By extracting the states' Fisher information, we observe that their phase sensitivities increase with N , showing the same scaling as ideal Twin-Fock states. vspace Our technique offers the potential for scaling to much larger particle numbers, presenting promising applications in quantum information with indistinguishable particles and Heisenberg- limited atom interferometry.