Laser cooling in an optical lattice that employs Raman transitions

Zhang, R.; Morrow, Natalya; Berman, P. R.; Raithel, Georg

doi:10.1103/physreva.72.043409

Cited by 15 publications

(17 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The radial matrix element in Eq. (14) can be deduced from the measured lifetime of the excited state, which yields in our case 5S 1/2 er 5P 1/2 = √ 3(2.9919 ± 0.0030) ea 0 [25,26]. Note that the factor of √ 3 stems from the angular integration since we consider the radial matrix element in our calculations.…”

Section: Van Vleck Perturbation Theorymentioning

confidence: 95%

“…Note that the factor of √ 3 stems from the angular integration since we consider the radial matrix element in our calculations. The individual contributions of the matrix (14) can be interpreted as follows. The diagonal elements stem from the lightshift potential of the lasers, that is, the off-resonant coupling of a m F component of the ground state to an excited state.…”

Section: Van Vleck Perturbation Theorymentioning

confidence: 99%

“…In a more recent approach, two lasers in a Raman configuration were used to trap atoms. Such a setup allows, for example, the creation of optical lattices with a reduced lattice spacing compared to standard optical lattices [14].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Creating versatile atom traps by applying near-resonant laser light in magnetic traps

et al. 2010

View full text Add to dashboard Cite

We utilize the combination of two standard trapping techniques, a magnetic trap and an optical trap in a Raman setup, to propose a versatile and tunable trap for cold atoms. The created potential provides several advantages over conventional trapping potentials. One can easily convert the type of the trap, for example, from a single-well to a double-well trap. Atoms in different internal states can be trapped in different trap types, thereby enabling the realization of experiments with multicomponent Bose-Einstein condensates. Moreover, one can achieve variations of the trapping potential on small length scales without the need of microstructures. We present the potential surfaces for different setups, demonstrate their tunability, give a semianalytical expression for the potential, and propose experiments which can be realized within such a trap.

show abstract

Section: Van Vleck Perturbation Theorymentioning

confidence: 95%

Section: Van Vleck Perturbation Theorymentioning

confidence: 99%

See 1 more Smart Citation

Creating versatile atom traps by applying near-resonant laser light in magnetic traps

et al. 2010

View full text Add to dashboard Cite

show abstract

“…The ability of real-time spatial imaging of the structures with sub-wavelength period is of particular interest for study cold atoms in optical lattice [7]. …”

mentioning

confidence: 99%

Sub-optical wavelength spatial imaging of the periodic fringes of total atomic density

Tonyushkin

Sleator

2006

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference

View full text Add to dashboard Cite

Fringes of total atomic density produced in an atom interferometer consisting of two off-resonant standing wave pulses were directly imaged using an "optical mask" technique. Fringe periods with integer fractions of the standing-wave period were observed.An interferometer based on the interaction of a pair of off-resonant standing waves (made from laser fields with wavelength λ) with a cold gas of Rb atoms [1] has been shown to be capable of precision measurement of the atomic recoil frequency, and inertial forces such as gravity. In the experiment, two standing wave pulses separated by time T , and detuned from an atomic transition of 85 Rb were applied to a sample of atoms cooled in a magneto-optical trap (MOT). In the vicinity of a time 2T an atomic fringe pattern with period λ/2 was observed indirectly by observing the back-scattering of light of wavelength λ from the sample.Theory predicts that at times t = [(n + 1)/n]T + ∆t, with ∆t T , fringe patterns of the total atomic density of period λ/2n should appear. Such fringes are the manifestation of the matter-wave diffraction. These gratings are not visible by the backscattering of traveling waves of wavelength λ, since the phase matching condition is not satisfied. Evidence of these λ/2n period gratings has been observed indirectly [2], but no direct observation of small-period fringes has been observed until now.To observe such small period structures, we have developed a real-time imaging technique [3]. This "optical mask" [4] technique, was applied to atoms of 85 Rb initially prepared in the ground hyperfine level F=3. In this technique a "mask" standing wave is applied to the atoms, and is resonant to the F=3 → F =3 transition (5S 1/2 → 5P 3/2 , λ = 780 nm). An excited atom is lost into the other ground hyperfine level, F=2, with 4/9 probability. For a pulse of sufficient intensity and duration, atoms not located at the nodes will be depleted into the F=2 level.For imaging the density at a particular time, we applied a "detection sequence", consisting of an optical mask, identical to the one described above (tuned to the F=3 → F =3 transition), followed by a traveling wave pulse tuned to the closed transition F=3 → F =4. After the mask was applied, atoms left unpumped at the nodes were counted by observation of fluorescence in the traveling wave. The fluorescent signal is proportional to the density at the nodes just before the application of the imaging mask. To map out the density as a function of position, the initial density profile was reproduced and the measurement repeated with various locations of the detection mask node within the mask period (λ/2).In the results presented here, we have applied the optical mask technique to directly measure the fringe spacing in an atom interferometer of the type described above. The optical mask was used to measure the atomic density fringes at various times after the two off-resonant standing waves [5].At a time around t = (3/2)T , we observed fringes with period λ/4 as shown in Fig. 1. Interestingly, there is...

show abstract

“…A dominant feature of the recent experiment [10] was high loss rates, attributed to non-adiabatic Landau-Zener transitions [14]. We should mention other methods which may be adapted to increase on-site interactions in a lattice include tunable scattering lengths and Feshbach resonances [15,16], and other methods proposed to give sub-half-wavelength structure to optical lattices, for example Raman processes [17,18].The phase transition from the superfluid state ceases to be adiabatic when the inverse timescale 1/τ becomes of the same order of magnitude as the frequencies of the lowest lying excitations, which are ∼ U in the limit U ≫ J; increasing U will decrease the number fluctuations in the final state. Furthermore, when finite temperature effects are taken into account, it has been shown that increasing U increases the purity of the final state [19], as one would expect from thermodynamic considerations.…”

mentioning

confidence: 99%

Enhancement of on-site interactions of tunneling ultracold atoms in optical potentials using radio-frequency dressing

2008

View full text Add to dashboard Cite

We show how it is possible to more than double the on-site interaction energy of neutral atoms in optical potentials by the technique of radio-frequency (rf) dressing, while maintaining interwell dynamics. We calculate Bose-Hubbard parameters for rf dressed optical lattices and arrays of rf dressed dipole traps. We show that decreasing the distance between wells, by the interpolation of wells confining different mF states, increases the interaction energy more than decreasing the height of the classically forbidden region between existing wells. The schemes we propose have negligible Landau-Zener losses caused by atomic motion; this was a dominant effect in the first experimental demonstration of the modification of an optical potential by radio-frequency dressing.PACS numbers: 03.75. Lm, 34.50.Cx, 37.10.Jk, 64.70.Tg, 67.85.Hj The study of complex nonlinear quantum systems is a major area of research in the fields of atomic and condensed matter physics. A subject of current interest is the effect of the nonlinear interaction term on the behaviour of ultracold atoms confined in optical lattices. The dynamics of ultracold bosonic atoms in such a system has been shown to be described by the Bose-Hubbard Hamiltonian [1]where i and j denote lattice sites of a homogeneous lattice. The ground state of the Bose-Hubbard Hamiltonian passes from superfluid to Mott insulator as the parameters controlling U and J are varied; this behaviour has been demonstrated experimentally [2]. The on-site interaction energy, the Hubbard U , is the dominant parameter characterising interactions between ultracold atoms in optical lattices. As such it plays a pivotal role in phase transitions [2] and entanglement [3]. The ability to generate complex entangled states has drawn interest to these systems for the purposes of quantum computing [4] and quantum simulation [5]. Typically, the magnitude of U controls the purity of the resulting many-particle state, or the speed at which this entanglement may be generated [6]. It is likely that there are a significant number of 'impurity' atoms present in the Mott insulator states currently being made [3,7]; for applications such as quantum computing and simulation it is desirable to reduce the number of these impurities as much as possible. Furthermore, by increasing the on-site interaction relative to the tunnelling energy, it may be possible to push optical lattice systems into new regimes, for example where the on-site interaction energy is greater than the band gap [8]. * Electronic address: m.shotter@physics.ox.ac.ukIn this paper we study ways to increase the on-site interaction energy, U , while still maintaining slow interwell dynamics, using the technique of radio-frequency (rf) dressing of optical potentials. We study both optical lattices and arrays of highly focused laser dipole spots, both seen as promising systems for quantum information processing [5,9]. We restrict our study to dressing the optical potential along a single direction of the lattice. The atoms in these potentials wil...

show abstract

Laser cooling in an optical lattice that employs Raman transitions

Cited by 15 publications

References 20 publications

Creating versatile atom traps by applying near-resonant laser light in magnetic traps

Creating versatile atom traps by applying near-resonant laser light in magnetic traps

Sub-optical wavelength spatial imaging of the periodic fringes of total atomic density

Enhancement of on-site interactions of tunneling ultracold atoms in optical potentials using radio-frequency dressing

Contact Info

Product

Resources

About