Bose-Einstein Condensation in Microgravity van Zoest, T; Gaaloul, N; Singh, Y ...
Science (American Association for the Advancement of Science),
06/2010, Letnik:
328, Številka:
5985
Journal Article
Recenzirano
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.
Atom interferometers covering macroscopic domains of space-time are a spectacular manifestation of the wave nature of matter. Because of their unique coherence properties, Bose-Einstein condensates ...are ideal sources for an atom interferometer in extended free fall. In this Letter we report on the realization of an asymmetric Mach-Zehnder interferometer operated with a Bose-Einstein condensate in microgravity. The resulting interference pattern is similar to the one in the far field of a double slit and shows a linear scaling with the time the wave packets expand. We employ delta-kick cooling in order to enhance the signal and extend our atom interferometer. Our experiments demonstrate the high potential of interferometers operated with quantum gases for probing the fundamental concepts of quantum mechanics and general relativity.
Bose-Einstein condensates in microgravity VOGEL, A; SCHMIDT, M; STEINMETZ, T ...
Applied physics. B, Lasers and optics,
09/2006, Letnik:
84, Številka:
4
Conference Proceeding, Journal Article
Recenzirano
We report the current status of our cooperative effort to realize a 87Rb Bose--Einstein condensate in microgravity. Targeting the long-term goal of studying cold quantum gases on a space platform, we ...currently focus on the implementation of an experiment at the ZARM drop tower in Bremen. Fulfilling the technical requirements for operation in this facility, the complete experimental setup will fit in a volume of less than 1 m3 with a total mass below 150 kg and a total power consumption of the order of 625 W. The individual parts of the setup, in particular the ultra-compact laser system as a critical component, are presented. In addition, we discuss a first demonstration of the mechanical and frequency control stability of the laser modules. On the theoretical side, we outline the non-relativistic description of a freely falling many-particle system in the rotating frame of the Earth. In particular, we show that the time evolution of a harmonically trapped, collisionally interacting degenerate gas of bosons or fermions is as simple in an accelerated, rotating frame of reference as in an inertial frame. By adopting a co-moving generalized Galilean frame, we can eliminate inertial forces and torques. This leads to important simplifications for numerical simulation of the experiment.
We experimentally demonstrate the possibility of preparing ultracold atoms in the environment of weightlessness at the earth-bound short-term microgravity laboratory Drop Tower Bremen, a facility of ...ZARM -- University of Bremen. Our approach is based on a freely falling magneto-optical trap (MOT) drop tower experiment performed within the ATKAT collaboration ('Atom-Catapult') as a preliminary part of the QUANTUS pilot project ('Quantum Systems in Weightlessness') pursuing a Bose--Einstein condensate (BEC) in microgravity at the drop tower 1, 2. Furthermore we give a complete account of the specific drop tower requirements to realize a compact and robust setup for trapping and cooling neutral rubidium 87Rb atoms in microgravity conditions. We also present the results of the first realized freely falling MOT and further accomplished experiments during several drops.
Atom interferometers covering macroscopic domains of space-time are a spectacular manifestation of the wave nature of matter. Due to their unique coherence properties, Bose-Einstein condensates are ...ideal sources for an atom interferometer in extended free fall. In this paper we report on the realization of an asymmetric Mach-Zehnder interferometer operated with a Bose-Einstein condensate in microgravity. The resulting interference pattern is similar to the one in the far-field of a double-slit and shows a linear scaling with the time the wave packets expand. We employ delta-kick cooling in order to enhance the signal and extend our atom interferometer. Our experiments demonstrate the high potential of interferometers operated with quantum gases for probing the fundamental concepts of quantum mechanics and general relativity.
We show that light-induced atom desorption (LIAD) can be used as a flexible atomic source for large {sup 87}Rb and {sup 40}K magneto-optical traps. The use of LIAD at short wavelengths allows for ...fast switching of the desired vapor pressure and permits experiments with long trapping and coherence times. The wavelength dependence of the LIAD effect for both species was explored in a range from 630 to 253 nm in an uncoated quartz cell and a stainless steel chamber. Only a few mW/cm{sup 2} of near-UV light produce partial pressures that are high enough to saturate a magneto-optical trap at 3.5x10{sup 9} {sup 87}Rb atoms or 7x10{sup 7} {sup 40}K atoms. Loading rates as high as 1.2x10{sup 9} {sup 87}Rb atoms/s and 8x10{sup 7} {sup 40}K atoms/s were achieved without the use of a secondary atom source. After the desorption light is turned off, the pressure quickly decays back to equilibrium with a time constant as short as 200 {mu}s, allowing for long trapping lifetimes after the MOT loading phase.
Space-Time Asymmetry Research (STAR) is a proposed satellite mission that aims for significantly improved tests of fundamental space-time symmetry and the foundations of special and general ...relativity. In the current concept, STAR comprises a series of three subsequent missions with increasingly advanced instruments performing clock to clock comparisons. While the first STAR missions will perform Kennedy-Thorndike (KT) and Michelson-Morley (MM) experiments, later missions will focus on fundamental gravitational physics by precision measurement of gravitational redshift, time dilation and Local Position Invariance (LPI). Compared to previous experimental accuracy, STAR aims for an improvement of at least two orders of magnitude. The STAR1 mission will measure the constancy of the speed of light to one part in 10 -17 and derive the Kennedy Thorndike coefficient of the Mansouri-Sexl test theory to 7 × 10 -10 . The KT experiment will be performed by comparison of an atomic or molecular frequency reference with a length reference (highly stable cavity made e.g. from ultra low expansion (ULE) glass ceramics) during flight around Earth with an orbital velocity of 7 km/s. The corresponding sensitivity to a boost dependent violation of Lorentz invariance as modeled by the KT term in the Mansouri-Sexl test theory or a Lorentz violating extension of the standard model (SME) will be significantly enhanced as compared to Earth-based experiments. The space environment will enhance the measurement precision such that an overall improvement by a factor of 400 over current Earth bound experiments is expected. The STAR1 philosophy is to realize a fast, small - and therefore cheap - mission with a high scientific output, also providing the instrument technology and the spacecraft for the subsequent STAR missions, which plan to use different optical frequency standards. The 180 kg small satellite will be attitude, vibration and temperature controlled. The power consumption of the whole spacecraft will be less than 185 W. The launch of STAR1 is foreseen for 2015, the follow-on missions will be flown with an overlap with the previous mission by two to three years. Each mission has a maximum duration of 5 years (from mission set up to data acquisition) which permits students to experience the full mission lifecycle. Education and training of undergraduate and graduate students is a specific mission goal.
Phys. Rev. A 73, 013410 (2006) We show that light-induced atom desorption (LIAD) can be used as a flexible
atomic source for large Rb-87 and K-40 magneto-optical traps. The use of LIAD
at short ...wavelengths allows for fast switching of the desired vapor pressure
and permits experiments with long trapping and coherence times. The wavelength
dependence of the LIAD effect for both species was explored in a range from 630
nm to 253 nm in an uncoated quartz cell and a stainless steel chamber. Only a
few mW/cm^2 of near-UV light produce partial pressures that are high enough to
saturate a magneto-optical trap at 3.5 x 10^9 Rb atoms or 7 x 10^7 K atoms.
Loading rates as high as 1.2 x 10^9 Rb atoms/s and 8 x 10^7 K atoms/s were
achieved without the use of a secondary atom source. After the desorption light
is turned off, the pressure quickly decays back to equilibrium with a time
constant as short as 200 us, allowing for long trapping lifetimes after the MOT
loading phase.
Degenerate Bose-Fermi gases in microgravity Herr, W.; van Zoest, T.; Gaaloul, N. ...
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference,
2009-June
Conference Proceeding
Summary form only given. Bose Einstein condensates (BEC) opened the way for realization of atomic ensembles with Heisenberg limited uncertainty. In microgravity extremely dilute samples of BEC can be ...obtained and observed after a free evolution on timescales of seconds. Applications range from atom optics to matter wave interferometry. This has led us to realize a BEC of 10000 87Rb atoms in microgravity. The experimental results (to be published) establish the fact, that in a microgravity environment ultra-large condensates (Icircosl.5 mm) after a free evolution of 1 second can be observed. In particular, microgravity provides mass independent confining potential which is very important for the research on a mixture of quantum gases. We aim to realize a new setup for multispecies experiments, which can be used in catapult mode doubling the time for microgravity to 9 seconds. The experiment is planned to use 87 Rb and 40 K as degenerate Bose and Fermi gases respectively and can be used to carry out experiments on interferometry, Bose-Fermi mixtures and tests of the weak equivalence principle in quantum domain. Up to date progress and future prospects of this ambitious and technically challenging project will be presented.
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