Bose-Einstein Condensation in Microgravity

Abstract

Albert Einstein's insight that it is impossible to distinguish a local experiment in a "freely falling elevator" from one in free space led to the development of the theory of general relativity. The wave nature of matter manifests itself in a striking way in Bose-Einstein condensates, where millions of atoms lose their identity and can be described by a single macroscopic wave function. We combine these two topics and report the preparation and observation of a Bose-Einstein condensate during free fall in a 146-meter-tall evacuated drop tower. During the expansion over 1 second, the atoms form a giant coherent matter wave that is delocalized on a millimeter scale, which represents a promising source for matter-wave interferometry to test the universality of free fall with quantum matter.

Quantum-measurement backaction from a Bose-Einstein condensate coupled to a mechanical oscillator

“…In this context, hybrid systems consisting of coupled atomic (or molecular) and nanomechanical systems may prove particularly useful. The robust and scalable infrastructure provided by micro-and nanoelectromechanical systems, coupled with the high-precision-measurement capability of quantum gases [5][6][7][8], makes them an attractive combination for sensitive force measurements, as well as for a quantitative study of dissipation and decoherence processes at the quantum-classical interface. As a result, there are ongoing experimental [9,10] and theoretical [11][12][13][14][15] efforts toward coupling mechanical systems to atomic ensembles.…”

The Momentum Distribution of Liquid $$^4\hbox {He}$$

“…The spontaneously broken gauge symmetry produces many fundamental properties of superfluid 4 He, such as its two-fluid hydrodynamics, critical exponents, and quantization of circulation. Recent interest in Bose condensation encompasses a broad range of topics 4 , including dilute atomic gases 5 , solid state excitations [6][7][8][9][10][11] , non-linear optical systems 12,13 , neutron stars 14 , and gravitation [15][16][17] . Bulk superfluid 4 He represents the strongly interacting limit of Bosecondensed systems due to the steeply repulsive core of its interatomic potential.…”

Inertial quantum sensors using light and matter

“…Nevertheless, our quest for improving the sensitivity of ground-based atom interferometers will soon reach a limit imposed by gravity and by the requirements of ultra-high vacuum and a very well controlled environment. Current state-of-the-art experimental apparatuses allow for seconds of interrogation with 10 to 120 meters of free-fall [69,70,71,72,67]. Space-based applications ‡, currently under study, will enable physicists to increase even further the interrogation time, thereby increasing dramatically the sensitivity and accuracy of atom interferometers.…”

“…For a cloud of bosonic (integer spin) atoms, all the atoms accumulate in the same quantum state (the atomoptical analog of the laser effect in optics). Access to BECs and atom laser sources have brought major conceptual advances in atom interferometry [68,69,70,71,72], in a similar fashion to what lasers did for the field of optical interferometry. Nevertheless, the relative complexity of BEC production has pushed scientists to explore new techniques by using, for instance, optical traps [73], atom chips [74], or avoiding evaporation and relying solely on laser cooling [75].…”