共查询到20条相似文献,搜索用时 31 毫秒
1.
M. Okano H. Hara M. Muramatsu K. Doi S. Uetake Y. Takasu Y. Takahashi 《Applied physics. B, Lasers and optics》2010,98(4):691-696
We have successfully implemented the first simultaneous magneto-optical trapping (MOT) of lithium (6Li) and ytterbium (174Yb) atoms towards production of ultracold polar molecules of LiYb. For this purpose, we developed the dual atomic oven which
contains both atomic species as an atom source and successfully observed the spectra of the Li and Yb atoms in the atomic
beams from the dual atomic oven. We constructed the vacuum chamber including the glass cell with the windows made of zinc
selenium (ZnSe) for the CO2 lasers, which are the useful light sources of optical trapping for evaporative and sympathetic cooling. Typical atom numbers
and temperatures in the compressed MOT are 7×103 atoms, 640 μK for 6Li, 7×104 atoms, and 60 μK for 174Yb, respectively. 相似文献
2.
Hadzibabic Z Stan CA Dieckmann K Gupta S Zwierlein MW Görlitz A Ketterle W 《Physical review letters》2002,88(16):160401
We have produced a macroscopic quantum system in which a 6Li Fermi sea coexists with a large and stable 23Na Bose-Einstein condensate. This was accomplished using interspecies sympathetic cooling of fermionic 6Li in a thermal bath of bosonic 23Na. The system features rapid thermalization and long lifetimes. 相似文献
3.
Silber C Günther S Marzok C Deh B Courteille PW Zimmermann C 《Physical review letters》2005,95(17):170408
We report on the observation of sympathetic cooling of a cloud of fermionic 6Li atoms which are thermally coupled to evaporatively cooled bosonic 87Rb. Using this technique we obtain a mixture of quantum-degenerate gases, where the Rb cloud is colder than the critical temperature for Bose-Einstein condensation and the Li cloud is colder than the Fermi temperature. From measurements of the thermalization velocity we estimate the interspecies s-wave triplet scattering length |amx|=20(+9)(-6)aB. We found that the presence of residual rubidium atoms in the |2, 1> and the |1, -1> Zeeman substates gives rise to important losses due to inelastic collisions. 相似文献
4.
Evaporative cooling of ultracold Yb atoms near the quantum-degenerate regime was experimentally studied. Three bosons of 170Yb, 172Yb, 176Yb and two fermions of 171Yb and 173Yb were evaporatively cooled in a crossed far-off resonant trap (FORT). We observed that 170Yb and 172Yb were not concentrated into the crossed region. We found that, in the cases of 176Yb atoms, atoms were concentrated well into the crossed region. The following evaporative cooling in the crossed region, however, did not work well. We performed the simultaneous trapping and sympathetic cooling in the crossed FORT by use of 172Yb-174Yb, 174Yb-176Yb, 172Yb-176Yb, and 171Yb-174Yb pairs. We observed that evaporative cooling worked well. This result shows that we succeeded in the enhancement of the atom collision rate. Especially, by use of 174Yb-176Yb mixture, we obtained cold 176Yb whose phase space density was 0.02. We observed a large atom loss, which limited the further sympathetic evaporative cooling. We also evaporatively cooled 174Yb in a 1D optical lattice. Evaporative cooling worked very well because the atoms were initially trapped at a high density. After evaporative cooling, we obtained very cold atoms, and T/T F was estimated to be 1.2. 相似文献
5.
We realize simultaneous quantum degeneracy in mixtures consisting of the alkali and alkaline-earth-like atoms Li and Yb. This is accomplished within an optical trap by sympathetic cooling of the fermionic isotope ?Li with evaporatively cooled bosonic 1??Yb and, separately, fermionic 1?3Yb. Using cross-thermalization studies, we also measure the elastic s-wave scattering lengths of both Li-Yb combinations, |a(?Li-1??Yb)| = 1.0 ± 0.2 nm and |a(?Li-1?3Yb)| = 0.9 ± 0.2 nm. The equality of these lengths is found to be consistent with mass-scaling analysis. The quantum degenerate mixtures of Li and Yb, as realized here, can be the basis for creation of ultracold molecules with electron spin degrees of freedom, studies of novel Efimov trimers, and impurity probes of superfluid systems. 相似文献
6.
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 6Li and 40K gases by an evaporatively cooled bosonic 87Rb 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 6Li gas by 87Rb is increased by the presence of 40K through catalytic cooling. Because of the differing physical properties of the two components, the quantum degenerate 6Li-40K Fermi-Fermi mixture is an excellent candidate for a stable, heteronuclear system allowing the study of several so far unexplored types of quantum matter. 相似文献
7.
We carry out the first quantum dynamics calculations on ultracold atom-diatom collisions in isotopic mixtures. The systems studied are spin-polarized 7Li + 6Li7Li, 7Li + 6Li2, 6Li + 6Li7Li, and 6Li + 7Li2. Reactive scattering can occur for the first two systems even when the molecules are in their ground rovibrational states, but is slower than vibrational relaxation in homonuclear systems. Implications for sympathetic cooling of heteronuclear molecules are discussed. 相似文献
8.
S. K. Tokunaga W. Skomorowski P. S. Żuchowski R. Moszynski J. M. Hutson E. A. Hinds M. R. Tarbutt 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(1-2):141-149
We consider how trapped molecules can be sympathetically cooled by ultracold atoms. As a prototypical system, we study LiH molecules co-trapped with ultracold Li atoms. We calculate the elastic and inelastic collision cross sections of 7LiH + 7Li with the molecules initially in the ground state and in the first rotationally excited state. We then use these cross sections to simulate sympathetic cooling in a static electric trap, an ac electric trap, and a microwave trap. In the static trap we find that inelastic losses are too great for cooling to be feasible for this system. The ac and microwave traps confine ground-state molecules, and so inelastic losses are suppressed. However, collisions in the ac trap can take molecules from stable trajectories to unstable ones and so sympathetic cooling is accompanied by trap loss. In the microwave trap there are no such losses and sympathetic cooling should be possible. 相似文献
9.
Measurement of S-Wave Scattering Length between ~6Li and ~(88)Sr Atoms Using Interspecies Thermalization in an Optical Dipole Trap
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We report the creation of the first mixture of ~6 Li and ~(88) Sr atoms in an optical dipole trap. Using this mixture,a measurement of the interspecies thermalization process is carried out and the previously unknown interspecies s-wave scattering length between ~6 Li and ~(88) Sr atoms is extracted to be |~(a6) Li-~(88) Sr| =(380_(-100)~(+160))a_0 with a_0 being the Bohr radius from the rate of interspecies thermalization. 相似文献
10.
Ferrari G Inguscio M Jastrzebski W Modugno G Roati G Simoni A 《Physical review letters》2002,89(5):053202
We determine the interspecies s-wave triplet scattering length a(3) for all K-Rb isotopic mixtures by measuring the elastic cross section for collisions between 41K and 87Rb in different temperature regimes. The positive value a(3)=+163(+57)(-12)a(0) ensures the stability against collapse of binary (41)K- (87)Rb Bose-Einstein condensates. For the fermion-boson mixture (40)K- (87)Rb, we obtain a large and negative scattering length which implies an efficient sympathetic cooling of the fermionic species down to the degenerate regime. 相似文献
11.
H. W. Cho D. J. McCarron D. L. Jenkin M. P. Köppinger S. L. Cornish 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(1-2):125-131
We report the production of a high phase-space density mixture of 87Rb and 133Cs atoms in a levitated crossed optical dipole trap as the first step towards the creation of ultracold RbCs molecules via magneto-association. We present a simple and robust experimental setup designed for the sympathetic cooling of 133Cs via interspecies elastic collisions with 87Rb. Working with the |F = 1,m F = +1〉 and the |3, +3〉 states of 87Rb and 133Cs respectively, we measure a high interspecies three-body inelastic collision rate ~10?25?10?26 cm6 ? s?1 which hinders the sympathetic cooling. Nevertheless by careful tailoring of the evaporation we can produce phase-space densities near quantum degeneracy for both species simultaneously. In addition we report the observation of an interspecies Feshbach resonance at 181.7(5) G and demonstrate the creation of Cs2 molecules via magneto-association on the 4(g)4 resonance at 19.8 G. These results represent important steps towards the creation of ultracold RbCs molecules in our apparatus. 相似文献
12.
Hadzibabic Z Gupta S Stan CA Schunck CH Zwierlein MW Dieckmann K Ketterle W 《Physical review letters》2003,91(16):160401
We have produced a quantum degenerate 6Li Fermi gas with up to 7 x 10(7) atoms, an improvement by a factor of 50 over all previous experiments with degenerate Fermi gases. This was achieved by sympathetic cooling with bosonic 23Na in the F=2, upper hyperfine ground state. We have also achieved Bose-Einstein condensation of F=2 sodium atoms by direct evaporation. 相似文献
13.
We successfully produced periodic ytterbium (Yb) narrow lines on a substrate using near-resonant laser light and the direct-write atom-lithography technique. The Yb atom is a promising material for nanofabrication using atom optics due to its electrical conductivity, the laser wavelength required for handling the atoms, the vapor pressure of the fabrication process, etc. The 174Yb atoms collimated by Doppler cooling were channeled by the dipole force of an optical standing wave and then deposited onto a substrate. We clearly observed a grating pattern of Yb atoms fabricated on the substrate with a line separation of approximately 200 nm after examining the surface of the substrate with atomic force microscope. This is the first demonstration of nanofabrication using the atom-optical approach with Yb atoms. PACS 32.80.-t; 32.80.-Pj 相似文献
14.
We study the collective dynamics in a degenerate Bose–Fermi mixture of 174Yb and 173Yb atoms. We excite collective oscillations by a sudden reduction of the trapping confinement and observe low m=0 quadrupole oscillations of condensates in 174Yb. First the oscillations in 174Yb atoms alone are investigated, and they are well described by the time-dependent Gross–Pitaevskii equation in the Thomas–Fermi approximation. Using the same procedure the quadrupole oscillations are excited for a 174Yb–173Yb Bose–Fermi mixture. In comparing data taken with and without fermionic 173Yb atoms, the oscillation frequency of the quadrupole mode in the condensate decreases with the presence of 173Yb atoms. 相似文献
15.
We report the realization of ytterbium magneto-optical trap (MOT) operating on the dipole-allowed ^1S0 - ^1P1 transition at 398.9nm. The MOT is loaded by a slowed atomic beam produced by a Zeeman slower. All seven stable isotopes of Yb atoms could be trapped separately at different laser detuning values. Over 10^7 174 Yb atoms are collected in the MOT, whereas the atom number of fermionic isotope ^171Yb is roughly 2.3 × 10^6 due to a lower abundance. Without the Zeeman slower the trapped atom numbers are one order of magnitude lower. Both the even and odd isotopes are recognized as excellent candidates of optical clock transition, so the cooling and trapping of ytterbium atoms by the blue MOT is an important step for building an optical clock. 相似文献
16.
The decay of 5.4 min 174Tm has been investigated using Ge(Li) spectrometers in singles and coincidence measurements. A total of 43 γ-ray transitions, 26 of them not reported before, have been observed following the decay of 174Tm. All transitions could be placed in a level scheme comprising 19 excited states of 174Yb. The Nilsson model has been used to interpret the level structure. The mixing of two-quasineutron and two-quasiproton states is studied and the experimental mixing matrix element is compared with the results of theoretical calculations. 相似文献
17.
We demonstrate the generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman slower. They are then subjected to a pair of molasses beams inclined at 45° with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate the selective deflection of the bosonic isotope 174Yb and the fermionic isotope 171Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK. 相似文献
18.
We describe an experimental setup designed to produce ultracold trapped gas clouds of fermionic 6Li and bosonic 87Rb. This combination of alkali metals has the potential to reach deeper Fermi degeneracy with respect to other mixtures since it allows for improved heat capacity matching which optimizes sympathetic cooling efficiency. Atomic beams of the two species are independently produced and then decelerated by Zeeman slowers. The slowed atoms are collected into a magneto-optical trap and then transferred into a quadrupole magnetic trap. An ultracold Fermi gas with temperature in the 10?3 T F range should be attainable through selective confinement of the two species via a properly detuned laser beam focused in the center of the magnetic trap. 相似文献
19.
Tojo S Kitagawa M Enomoto K Kato Y Takasu Y Kumakura M Takahashi Y 《Physical review letters》2006,96(15):153201
We observed high-resolution photoassociation spectra of laser-cooled ytterbium (Yb) atoms in the spin-forbidden 1S0 - 3P1 intercombination line. The rovibrational levels in the 0u+ state were measured for red detunings of the photoassociation laser ranging from 2.9 MHz to 1.97 GHz with respect to the atomic resonance. The rotational splitting of the vibrational levels near the dissociation limit were fully resolved due to the sub-MHz linewidth of the spectra in contrast to previous measurements using the spin-allowed singlet transition. In addition, from a comparison between the spectra of 174Yb and those of 176Yb, a d-wave shape resonance for 174Yb is strongly suggested. 相似文献
20.
Jun Dong A. Shirakawa K.-I. Ueda A.A. Kaminskii 《Applied physics. B, Lasers and optics》2007,89(2-3):359-365
The microchip laser performance of Yb:YAG crystals doped with different ytterbium concentrations (CYb=10, 15, and 20 at. %) has been investigated at ambient temperature without active cooling of the gain media. Efficient laser
oscillation for a 1-mm-thick YAG doped with 10 at. % Yb3+ ions was achieved at 1030 and 1049 nm with slope efficiencies of 85% and 81%, correspondingly. The laser performance of heavy-doped
Yb:YAG crystals was limited by the thermal population at terminated lasing level and thermal lens effect at room temperature
without sufficient cooling of the samples. The laser emitting spectra of Yb:YAG microchip lasers with different Yb concentrations
and output couplings are addressed with the local temperature rise, due to the absorption of the pump power inside the gain
media under different pump levels.
PACS 42.55.Xi; 42.70.Hj; 42.55.Rz 相似文献