Hypersonic Bose-Einstein condensates in accelerator rings.

Some of the most sensitive and precise measurements-for example, of inertia, gravity and rotation-are based on matter-wave interferometry with free-falling atomic clouds. To achieve very high sensitivities, the interrogation time has to be very long, and consequently the experimental apparatus needs to be very tall (in some cases reaching ten or even one hundred metres) or the experiments must be performed in microgravity in space. Cancelling gravitational acceleration (for example, in atomtronic circuits and matter-wave guides) is expected to result in compact devices with extended interrogation times and therefore increased sensitivity.

Simple precision measurements of optical beam sizes.

We present a simple high-precision method to quickly and accurately measure the diameters of Gaussian beams, Airy spots, and central peaks of Bessel beams ranging from sub-millimeter to many centimeters without specialized equipment. By simply moving a wire through the beam and recording the relative losses using an optical power meter, one can easily measure the beam diameters with a precision of 1%. The accuracy of this method has been experimentally verified for Gaussian beams down to the limit of a commercial slit-based beam profiler (3%).