Sub-atom shot noise Faraday imaging of ultracold atom clouds

Abstract

We demonstrate that a dispersive imaging technique based on the Faraday effect can measure the atom number in a large, ultracold atom cloud with a precision below the atom shot noise level. The minimally destructive character of the technique allows us to take multiple images of the same cloud, which enables sub-atom shot noise measurement precision of the atom number and allows for an in situ determination of the measurement precision. We have developed a noise model that quantitatively describes the noise contributions due to photon shot noise in the detected light and the noise associated with single atom loss. This model contains no free parameters and is calculated through an analysis of the fluctuations in the acquired images. For clouds containing $N\sim 5\times 10^6$ atoms, we achieve a precision more than a factor of two below the atom shot noise level.

arXiv comment10 pages, 8 figures

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• Continuum of classical-field ensembles from canonical to grand canonical and the onset of their equivalence
• Quantum supremacy of the many-body fluctuations in the occupations of the excited particle states in a Bose-Einstein-condensed gas
• Spatial calibration of high-density absorption imaging
• Dispersive detection of atomic ensembles in the presence of strong lensing
• Atom Number Fluctuations in Bose Gases -- Statistical analysis of parameter estimation
• On the fluctuations of the number of atoms in the condensate
• Loading ultracold atoms onto nonlinear Bloch states and soliton states in bichromatic lattices
• Polarization-Sensitive Imaging in Magnetic Environments
• Cloud parameter estimation for interacting BEC after time-of-flight