Figure 1

Simulation of propagation effects after light has passed through a Poissonian phase noise object. Shown are the variance measured in the amplitude or in-phase quadrature (black line) and the out-of-phase quadrature (gray line) as a function of defocus distance, for an imaging system with a numerical aperture of 0.14. Within a distance less than 5% of our cloud size, noise becomes equally distributed between the two quadratures and the variances in transmission and phase-contrast images become the same. (Top inset) For small phase fluctuations, an in-focus phase noise object gives no amplitude contrast, but when it is out of focus it does. (Bottom inset) Sample intensity patterns for a defocused phase object.Reuse & Permissions

Figure 2

Measured condensate fraction as a function of dimensionless interaction strength $1/(k_{F}a)$. Insets show typical images from which the condensate fraction was extracted by fitting a bimodal distribution. The dashed line is a sigmoidal fit to guide the eye.Reuse & Permissions

Figure 3

(Top panel) Example speckle noise image, with white box indicating analysis region. (Bottom panels) Noise data for noninteracting (left panel) and resonantly interacting (right panel) cold clouds, showing ${\Delta }_{-}^2$ (black dots) and ${\Delta }_{+}^2$ (gray dots). Solid lines are Gaussian fits to the data, and dotted lines illustrate the expected full Poissonian noise for the corresponding quantities based on density determined from off-resonant absorption.Reuse & Permissions

Figure 4

(a) The ratio $\chi /\kappa$, (b) the normalized susceptibility $\chi /{\chi }_0$, and (c) the normalized compressibility $\kappa /{\kappa }_0$ in the BEC-BCS crossover. The variances derived from sequences of images are converted into thermodynamic variables using the measured temperatures and a calibration factor determined from the noninteracting gas. The vertical line indicates the onset region of superfluidity, as determined via condensate fraction measurements. The curves show theoretical zero temperature estimates based on 1st (dotted) and 2nd order (solid) perturbative formulas obtained from Landau’s Fermi-liquid theory integrated along the line of sight, and results from a Monte Carlo calculation (dashed) for the compressibility in a homogeneous system [32].Reuse & Permissions