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1.
H. Kreutzmann A. Sanpera L. Santos M. Lewenstein D. Hellweg L. Cacciapuoti M. Kottke T. Schulte K. Sengstock J.J. Arlt W. Ertmer 《Applied physics. B, Lasers and optics》2003,76(2):165-172
Quasi-one-dimensional Bose–Einstein condensates (BECs) in elongated traps exhibit significant phase fluctuations even at very
low temperatures. We present recent experimental results on the dynamic transformation of phase fluctuations into density
modulations during time of flight and show the excellent quantitative agreement with the theoretical prediction. In addition
we confirm that, under our experimental conditions, in the magnetic trap density modulations are strongly suppressed even
when the phase fluctuates. We also discuss our theoretical results on control of the condensate phase by employing a time-dependent
perturbation. Our results set important limitations on future applications of BECs in precision atom interferometry and atom
optics, but at the same time suggest pathways to overcome these limitations.
Received: 17 August 2002 / Published online: 15 January 2003
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ID="*"Corresponding author. Fax: +49-511/762-3023, E-mail: Helge.Kreutzmann@ITP.uni-hannover.de 相似文献
2.
B. Löhden S. Kuznetsova K. Sengstock V. M. Baev A. Goldman S. Cheskis B. Pálsdóttir 《Applied physics. B, Lasers and optics》2011,102(2):331-344
Intracavity absorption spectroscopy with a broadband Er3+-doped fiber laser is applied for the measurements of several molecular species revealing quantitative information about the
gas concentration, temperature and chemical reactions in flames. The spectral range of measurements extends from 6200 cm−1 to 6550 cm−1 with the proper choice of the fiber length and by moving an intracavity lens. With a pulsed laser applied in this experiment,
the sensitivity to absorption corresponds to an effective absorption path length of 3 km assuming the cavity is completely
filled with the sample. For a cw laser, the effective absorption path length is estimated to be 50 km. Absorption spectra
of various molecules such as CO2, CO, H2O, H2S, C2H2 and OH were recorded separately in the cell and/or in low-pressure methane and propane flames. The presented measurements
demonstrate simultaneous in situ detection of three molecular products of chemical reactions at different flame locations.
Variation of the relative strengths of OH absorption lines with the temperature enables the estimation of the local flame
temperature. The sensitivity of this laser does not depend on the broadband cavity losses and it can be used for in situ measurements
of absorption spectra in hostile environments such as contaminated samples, flames or combustion engines. The presented technique
can be applied for various diagnostic purposes, such as in environmental, combustion and plasma research, in medicine and
in the determination of stable isotope ratios. 相似文献
3.
U. Sterr K. Sengstock J. H. Müller D. Bettermann W. Ertmer 《Applied physics. B, Lasers and optics》1992,54(5):341-346
In this paper it will be shown that an atom interferometer, based on the coherent splitting of the atomic wavefunction by four travelling waves (Ramsey interferometer), may be explained by a purely mechanical interpretation. As our first application of this Ramsey interferometer we have measured the phase shifts respectively optical length changes in a magnesium atomic beam caused by the acceleration of the partial atomic wave in one arm of the interferometer. This acceleration was achieved by the dipole force exerted by an off-resonant crossing laser beam which interacted with the ground state part of the wavefunction only. Further applications of this interferometer and improvements due to laser cooling will be discussed. 相似文献
4.
We have studied effects of interspecies attraction in a Fermi-Bose mixture over a large regime of particle numbers in the 40K-87Rb system. We report on the observation of a mean-field driven collapse at critical particle numbers of 1.2 x 10(6) 87Rb atoms in the condensate and 7.5 x 10(5) 40K atoms consistent with mean-field theory for a scattering length of aFB = -284a(0). For large overcritical particle numbers, we see evidence for revivals of the collapse. Part of our detailed study of the decay dynamics and mechanisms is a measurement of the (87Rb- 87Rb- 40K) three-body loss coefficient K3 = (2.8 +/- 1.1) x 10(-28) cm6/s, which is an important parameter for dynamical studies of the system. 相似文献
5.
Deuretzbacher F Fredenhagen K Becker D Bongs K Sengstock K Pfannkuche D 《Physical review letters》2008,100(16):160405
We present an exact analytical solution of the fundamental system of quasi-one-dimensional spin-1 bosons with infinite delta repulsion. The eigenfunctions are constructed from the wave functions of noninteracting spinless fermions, based on Girardeau's Fermi-Bose mapping. We show that the spinor bosons behave like a compound of noninteracting spinless fermions and noninteracting distinguishable spins. This duality is especially reflected in the spin densities and the energy spectrum. We find that the momentum distribution of the eigenstates depends on the symmetry of the spin function. Furthermore, we discuss the splitting of the ground state multiplet in the regime of large but finite repulsion. 相似文献
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D. Hellweg S. Dettmer P. Ryytty J.J. Arlt W. Ertmer K. Sengstock D.S. Petrov G.V. Shlyapnikov H. Kreutzmann L. Santos M. Lewenstein 《Applied physics. B, Lasers and optics》2001,73(8):781-789
We demonstrate the existence of phase fluctuations in elongated Bose–Einstein condensates (BECs) and study the dependence
of these fluctuations on the system parameters. A strong dependence on temperature, atom number, and trapping geometry is
observed. Phase fluctuations directly affect the coherence properties of BECs. In particular, we observe instances where the
phase-coherence length is significantly smaller than the condensate size. Our method of detecting phase fluctuations is based
on their transformation into density modulations after ballistic expansion. An analytic theory describing this transformation
is developed.
Received: 13 July 2001 / Revised version: 28 September 2001 / Published online: 23 November 2001 相似文献
9.
J. H. Müller D. Bettermann V. Rieger K. Sengstock U. Sterr W. Ertmer 《Applied physics. B, Lasers and optics》1995,60(2-3):199-204
Matter-wave interferences in a four-pulse version of a Ramsey-Bordé atom interferometer have been utilized to study phase shifts. A topological phase shift analogous to the scalar Aharonov-Bohm effect proposed for charged-particle interferences in the presence of a pulsed electrostatic potential has been investigated. The time-dependent potential has been generated by the interaction of a laser field with an induced atomic dipole without spatial variation along the interferometer arms. The atom interferometer has been run with laser-cooled magnesium atoms stored in a magneto-optical trap.Dedicated to H. Walther on the occasion of his 60th birthday 相似文献
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