Optimally focused cold atom systems obtained using density-density correlations

Abstract

Resonant absorption imaging is a common technique for detecting the two-dimensional column density of ultracold atom systems. In many cases, the system's thickness along the imaging direction greatly exceeds the imaging system's depth of field, making the identification of the optimally focused configuration difficult. Here we describe a systematic technique for bringing Bose-Einstein condensates (BEC) and other cold-atom systems into an optimal focus even when the ratio of the thickness to the depth of field is large: a factor of 8 in this demonstration with a BEC. This technique relies on defocus-induced artifacts in the Fourier-transformed density-density correlation function (the power spectral density, PSD). The spatial frequency at which these artifacts first appear in the PSD is maximized on focus; the focusing process therefore both identifies and maximizes the range of spatial frequencies over which the PSD is uncontaminated by finite-thickness effects.

6 pages, 3 figures

References in corpus (7)

• Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
• Single-Atom Resolved Fluorescence Imaging of an Atomic Mott Insulator
• Probing the Superfluid to Mott Insulator Transition at the Single Atom Level
• Spatial quantum noise interferometry in expanding ultracold atom clouds
• Strong saturation absorption imaging of dense clouds of ultracold atoms
• Extracting density-density correlations from in situ images of atomic quantum gases
• Probing Phase Fluctuations in a 2D Degenerate Bose Gas by Free Expansion

Cited by in corpus (8)

• Observation of ultracold atomic bubbles in orbital microgravity
• Probing the Degree of Coherence through the Full 1D to 3D crossover
• Scaling behavior of density fluctuations in an expanding quasi-2D degenerate Bose gas
• Atom Number Fluctuations in Bose Gases -- Statistical analysis of parameter estimation
• Multiple-camera defocus imaging of ultracold atomic gases
• On the fluctuations of the number of atoms in the condensate
• Cloud parameter estimation for interacting BEC after time-of-flight
• Self-Bayesian Aberration Removal via Constraints for Ultracold Atom Microscopy