We report the tomographic reconstruction of an atom-number-resolving detector. We characterize the fidelity of our detector and show that a negative-valued Wigner function is associated with it. Our results offer an exciting perspective for the high-fidelity reconstruction of entangled states and can be applied for a future demonstration of Heisenberg-limited atom interferometry.
The article is published on PRL: https://doi.org/10.1103/PhysRevLett.131.260601
