Figure 2: Characterization of the FGBS momentum output:

(a) The velocity difference between the two observed clouds as a function of the interaction time T. The error bars are calculated from the variation of a few data sets. The theoretical prediction (shaded area) is based on a measured current in a resistor that mimics the chip wire (inset), taking into account errors of ±2.5 μm (one pixel) in the initial cloud position, ±0.2 Ω in the wire resistance and a 1 μs delay of the measured rise-time (due to the resistor's inductance). The linear dependence on T is to be expected from the solution of equation (2). The current ‘overshoot’ at short times is responsible for the larger acceleration for small T. (b) Numerical integration of equation (2) over T, using the experimental wire configuration and using a constant current of 3A. We observe the limit of our specific FGBS realization due to the large distance that develops between the atoms and the wire. (c) Using improved experimental parameters, we find that Δp of above 100 ħk is possible in less than 10 μs. The parameters are: z=10 μm and I=2A, and the wire dimensions are 10 × 2 μm² (10⁷ A cm⁻² is safely achievable for such short pulses).