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Search Results: 1 - 10 of 302926 matches for " T W H?nsch "
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Transporting, splitting and merging of atomic ensembles in a chip trap
P. Hommelhoff,W. H?nsel,T. Steinmetz,T. W. Hnsch,J. Reichel
Physics , 2004, DOI: 10.1088/1367-2630/7/1/003
Abstract: We present a toolbox for cold atom manipulation with time-dependent magnetic fields generated by an atom chip. Wire layouts, detailed experimental procedures and results are presented for the following experiments: Use of a magnetic conveyor belt for positioning of cold atoms and Bose-Einstein condensates with a resolution of two nanometers; splitting of thermal clouds and BECs in adjustable magnetic double well potentials; controlled splitting of a cold reservoir. The devices that enable these manipulations can be combined with each other. We demonstrate this by combining reservoir splitter and conveyor belt to obtain a cold atom dispenser. We discuss the importance of these devices for quantum information processing, atom interferometry and Josephson junction physics on the chip. For all devices, absorption-image video sequences are provided to demonstrate their time-dependent behaviour.
Growth of Bose-Einstein Condensates from Thermal Vapor
M. K?hl,M. J. Davis,C. W. Gardiner,T. W. Hnsch,T. Esslinger
Physics , 2001, DOI: 10.1103/PhysRevLett.88.080402
Abstract: We report on a quantitative study of the growth process of $^{87}$Rb Bose-Einstein condensates. By continuous evaporative cooling we directly control the thermal cloud from which the condensate grows. We compare the experimental data with the results of a theoretical model based on quantum kinetic theory. We find quantitative agreement with theory for the situation of strong cooling, whereas in the weak cooling regime a distinctly different behaviour is found in the experiment.
Trapped-Atom-Interferometer in a Magnetic Microtrap
W. H?nsel,J. Reichel,P. Hommelhoff,T. W. Hnsch
Physics , 2001, DOI: 10.1103/PhysRevA.64.063607
Abstract: We propose a configuration of a magnetic microtrap which can be used as an interferometer for three-dimensionally trapped atoms. The interferometer is realized via a dynamic splitting potential that transforms from a single well into two separate wells and back. The ports of the interferometer are neighboring vibrational states in the single well potential. We present a one-dimensional model of this interferometer and compute the probability of unwanted vibrational excitations for a realistic magnetic potential. We optimize the speed of the splitting process in order suppress these excitations and conclude that such interferometer device should be feasible with currently available microtrap technique.
Applications of Integrated Magnetic Microtraps
J. Reichel,W. H?nsel,P. Hommelhoff,T. W. Hnsch
Physics , 2000, DOI: 10.1007/s003400000460
Abstract: Lithographically fabricated circuit patterns can provide magnetic guides and microtraps for cold neutral atoms. By combining several such structures on the same ceramic substrate, we have realized the first ``atom chips'' that permit complex manipulations of ultracold trapped atoms or de Broglie wavepackets. We show how to design magnetic potentials from simple conductor patterns and we describe an efficient trap loading procedure in detail. Applying the design guide, we describe some new microtrap potentials, including a trap which reaches the Lamb-Dicke regime for rubidium atoms in all three dimensions, and a rotatable Ioffe-Pritchard trap, which we also demonstrate experimentally. Finally, we demonstrate a device allowing independent linear positioning of two atomic clouds which are very tightly confined laterally. This device is well suited for the study of one-dimensional collisions.
Atom Chip for Transporting and Merging Magnetically Trapped Atom Clouds
W. H?nsel,J. Reichel,P. Hommelhoff,T. W. Hnsch
Physics , 2000,
Abstract: We demonstrate an integrated magnetic ``atom chip'' which transports cold trapped atoms near a surface with very high positioning accuracy. Time-dependent currents in a lithographic conductor pattern create a moving chain of magnetic potential wells; atoms are transported in these wells while remaining confined in all three dimensions. We achieve fluxes up to 10^6 /s with a negligible heating rate. An extension of this ``atomic conveyor belt'' allows the merging of magnetically trapped atom clouds by unification of two Ioffe-Pritchard potentials. Under suitable conditions, the clouds merge without loss of phase space density. We demonstrate this unification process experimentally.
Quantum degenerate two-species Fermi-Fermi mixture coexisting with a Bose-Einstein condensate
M. Taglieber,A. -C. Voigt,T. Aoki,T. W. Hnsch,K. Dieckmann
Physics , 2007, DOI: 10.1103/PhysRevLett.100.010401
Abstract: We report on the generation of a quantum degenerate Fermi-Fermi mixture of two different atomic species. The quantum degenerate mixture is realized employing sympathetic cooling of fermionic Li-6 and K-40 gases by an evaporatively cooled bosonic Rb-87 gas. We describe the combination of trapping and cooling methods that proved crucial to successfully cool the mixture. In particular, we study the last part of the cooling process and show that the efficiency of sympathetic cooling of the Li-6 gas by Rb-87 is increased by the presence of K-40 through catalytic cooling. Due to the differing physical properties of the two components, the quantum degenerate Li-6 K-40 Fermi-Fermi mixture is an excellent candidate for a stable, heteronuclear system allowing to study several so far unexplored types of quantum matter.
Observing the Profile of an Atom Laser Beam
M. K?hl,Th. Busch,K. Molmer,T. W. Hnsch,T. Esslinger
Physics , 2005, DOI: 10.1103/PhysRevA.72.063618
Abstract: We report on an investigation of the beam profile of an atom laser extracted from a magnetically trapped $^{87}$Rb Bose-Einstein condensate. The transverse momentum distribution is magnified by a curved mirror for matter waves and a momentum resolution of 1/60 of a photon recoil is obtained. We find the transverse momentum distribution to be determined by the mean-field potential of the residing condensate, which leads to a non-smooth transverse density distribution. Our experimental data are compared with a full 3D simulation of the output coupling process and we find good agreement.
Thermal-noise limited laser stabilization to a crystalline whispering-gallery-mode resonator
J. Alnis,A. Schliesser,C. Y. Wang,J. Hofer,T. J. Kippenberg,T. W. Hnsch
Physics , 2011,
Abstract: We have stabilized an external cavity diode laser to a whispering gallery mode resonator formed by a protrusion of a single-crystal magnesiumdifluoride cylinder. The cylinder's compact dimensions (<1 cm^3) reduce the sensitivity to vibrations and simplify the stabilization of its temperature in a compact setup. In a comparison to an ultrastable laser used for precision metrology we determine a minimum Allan deviation of 20 Hz, corresponding to a relative Allan deviation of 6*10^-14, at an integration time of 100 ms. This level of instability is compatible with the limits imposed by fundamental fluctuations of the material's refractive index at room temperature.
2S hyperfine structure of atomic deuterium
N. Kolachevsky,P. Fendel,S. G. Karshenboim,T. W. Hnsch
Physics , 2004, DOI: 10.1103/PhysRevA.70.062503
Abstract: We have measured the frequency splitting between the $(2S, F=1/2)$ and $(2S, F=3/2)$ hyperfine sublevels in atomic deuterium by an optical differential method based on two-photon Doppler-free spectroscopy on a cold atomic beam. The result $f_{\rm HFS}^{(D)}(2S)= 40 924 454(7)$ Hz is the most precise value for this interval to date. In comparison to the previous radio-frequency measurement we have improved the accuracy by the factor of three. The specific combination of hyperfine frequency intervals for metastable- and ground states in deuterium atom $D_{21}=8f_{\rm HFS}^{(D)}(2S)-f_{\rm HFS}^{(D)}(1S)$ derived from our measurement is in a good agreement with $D_{21}$ calculated from quantum-electrodynamics theory.
Frequency Metrology on single trapped ions in the weak binding limit: The 3s1/2-3p3/2 transition in 24-Mg+
M. Herrmann,V. Batteiger,S. Knünz,G. Saathoff,Th. Udem,T. W. Hnsch
Physics , 2008, DOI: 10.1103/PhysRevLett.102.013006
Abstract: We demonstrate a method for precision spectroscopy on trapped ions in the limit of unresolved motional sidebands. By sympathetic cooling of a chain of crystallized ions we suppress adverse temperature variations induced by the spectroscopy laser that usually lead to a distorted line profle and obtain a Voigt profile with negligible distortions. We applied the method to measure the absolute frequency of the astrophysically relevant D2 transition in single 24-Mg+ ions and find 1072082934.33(16)MHz, a nearly 400fold improvement over previous results. Further, we find the excited state lifetime to be 3.84(10) ns.
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