Short-Distance Atomic Beam Deceleration with a Stimulated Light Force

Söding, Johannes; Grimm, Rudolf; Ovchinnikov, Yu. N.; Bouyer, Philippe; Salomon, C.

doi:10.1103/physrevlett.78.1420

Cited by 113 publications

(127 citation statements)

References 24 publications

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“…As in previous work [2,6], the force is calculated at each velocity by use of Ehrenfest's theorem. The force profiles shown in Fig.…”

Section: Fig 2 (Color Online)mentioning

confidence: 99%

“…This direct numerical approach, originally developed by Söding and coworkers [2], has proven quite reliable for modeling the bichromatic force even in the presence of dynamically changing conditions [6]. We solve the OBEs in the form [7] …”

Section: A Numerical Solution Of the Optical Bloch Equationsmentioning

confidence: 99%

“…an atom) and the light field. Grimm and coworkers made use of rectified optical dipole forces to deflect an atomic Cs beam by several m/s [1], later improving on this result by developing the much stronger optical bichromatic force (BCF) and using it to decelerate the atoms nearly to rest [2]. The basic principles of the BCF, which utilizes two-color beams with symmetric detunings ±δ from resonance, are reviewed in Sec.…”

Section: Introductionmentioning

confidence: 99%

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Four-color stimulated optical forces for atomic and molecular slowing

2013

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Stimulated optical forces offer a simple and efficient method for providing optical forces far in excess of the saturated radiative force. The bichromatic force, using a counterpropagating pair of two-color beams, has so far been the most effective of these stimulated forces for deflecting and slowing atomic beams. We have numerically studied the evolution of a two-level system under several different bichromatic and polychromatic light fields, while retaining the overall geometry of the bichromatic force. New insights are gained by studying the time-dependent trajectory of the Bloch vector, including a better understanding of the remarkable robustness of bi-and polychromatic forces with imbalanced beam intensities. We show that a four-color polychromatic force exhibits great promise. By adding new frequency components at the third harmonic of the original bichromatic detuning, the force is increased by nearly 50% and its velocity range is extended by a factor of three, while the required laser power is increased by only 33%. The excited-state fraction, crucial to possible application to molecules, is reduced from 41% to 24%. We also discuss some important differences between polychromatic forces and pulse trains from a high-repetition-rate laser.

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“…As in previous work [2,6], the force is calculated at each velocity by use of Ehrenfest's theorem. The force profiles shown in Fig.…”

Section: Fig 2 (Color Online)mentioning

confidence: 99%

Section: A Numerical Solution Of the Optical Bloch Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Four-color stimulated optical forces for atomic and molecular slowing

2013

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“…While we propose a variation of this scheme utilizing chirped picosecond pulses, this force has been used with unchirped pulses to deflect molecular [21] and atomic [22,29] beams in the transverse direction. In this mode of operation, it bears some similarity to the bichromatic force [30][31][32]. This unchirped realization may be regarded as being (in some respects) the polychromatic limit of the bichromatic force [33].…”

Section: Ultrafast Laser Deceleration Forcementioning

confidence: 99%

Continuous all-optical deceleration and single-photon cooling of molecular beams

et al. 2014

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Ultracold molecular gases are promising as an avenue to rich many-body physics, quantum chemistry, quantum information, and precision measurements. This richness, which flows from the complex internal structure of molecules, makes the creation of ultracold molecular gases using traditional methods (laser plus evaporative cooling) a challenge, in particular due to the spontaneous decay of molecules into dark states. We propose a way to circumvent this key bottleneck using an alloptical method for decelerating molecules using stimulated absorption and emission with a single ultrafast laser. We further describe single-photon cooling of the decelerating molecules that exploits their high dark state pumping rates, turning the principal obstacle to molecular laser cooling into an advantage. Cooling and deceleration may be applied simultaneously and continuously to load molecules into a trap. We discuss implementation details including multi-level numerical simulations of strontium monohydride (SrH). These techniques are applicable to a large number of molecular species and atoms with the only requirement being an electric dipole transition that can be accessed with an ultrafast laser.

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“…We will not address these aspects, firstly because we do not consider dipolar forces or Sisyphean frictions [12], and secondly because several studies on standing wave lattices have shown that coherent (stimulated laser cooling or coherent population trapping) forces can indeed lead to "rectified" forces and provide confinement for sufficiently high laser intensity [13][14][15][16][17][18][19][20][21][22]. Similarly, we only study Doppler cooling even if laser fields considered in this letter can lead to sub-Doppler, velocity-selective coherent population trapping (VSCPT) or grey molasse cooling (see Refs [23][24][25][26] and reference therein).…”

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confidence: 99%

Bichromatic magneto-optical trapping forJ→J,J−1configurations

et al. 2016

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A magneto-optical trap (MOT) of atoms or molecules is studied when two lasers of different detunings and polarization are used. Especially for J → J, J − 1 transitions, a scheme using more than one frequency per transition and different polarization is required to create a significant force. Calculations have been performed with the simplest forms of the J → J − 1 case (i.e. J ′′ = 1 → J ′ = 0) and J → J case (i.e. J ′′ = 1/2 → J ′ = 1/2). A one dimensional (1D) model is presented and a complete 3D simulation using rate equations confirm the results. Even in the absence of Zeeman effect in the excited state, where no force is expected in the single laser field configuration, we show that efficient cooling and trapping forces are restored in our configuration. We study this mechanism for the C − 2 molecular anion as a typical example of the interplay between the two simple transitions J → J, J − 1. Laser cooling and magneto-optical trapping of atoms typically involves J → J + 1 closed transitions driven by counter-propagating circularly polarized laser fields (J is the total angular momentum). On the contrary laser forces on molecule, a more recent subject despite the pioneer experiments [1,2], typically involve N ′′ = 1 → N ′ = 0 transitions (N is the rotational quantum number) between X 2 Σ(v ′′ = 0) and A 2 Π 1/2 (v ′ = 0) vibronic levels [3][4][5]. Including the electron spin leads to J ′′ = 1/2, 3/2 → J ′ = 1/2 transitions. Theoretical study of the correct choice of circular polarization for magnetooptical trapping depending on the angular momenta, J ′′ and J ′ , and on the g-factors, g ′′ and g ′ (respectively of the lower and upper states) has been performed in Ref [6]. It has been found heuristically that the trapping force is weak whenever g ′ is small compared to g ′′ . This is a serious limitation because in pure Hund's case (a) or (b), A 2 Π 1/2 does not present any Zeeman effect [7], so g ′ = 0 prevents any force. However experiments, such as that on SrF [8], were possible because of rotational and spin-orbit Π − Σ mixing allowing a small non zero value for g ′ (∼ 0.1 [6]). In addition to this weak force, J ′′ = 1/2, 3/2 → J ′ = 1/2 transitions present one or two dark states [9, 10] which leads to experimental difficulties if a stronger confining force is desired. Yet stronger force can be produced by rapidly switching the magnetic field gradient and laser beam polarization on a timescale (typically in the sub-microsecond range which is not a simple experimental task) preventing the adiabatic following of the atomic states as done in reference [3] .In this letter we suggest that efficient magneto-optical forces can be restored in all J ′′ → J ′ cases, even for g ′ = 0, in a very simple way, by simply adding one laser field of opposite polarization with a different detuning. We treat the simplest J → J − 1 case (that * Corresponding author: anne.cournol@u-psud.fr is J ′′ = 1 → J ′ = 0) and J → J case (that is J ′′ = 1/2 → J ′ = 1/2). An analytical one dimensional (1D) model is presented and help get t...

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Short-Distance Atomic Beam Deceleration with a Stimulated Light Force

Cited by 113 publications

References 24 publications

Four-color stimulated optical forces for atomic and molecular slowing

Four-color stimulated optical forces for atomic and molecular slowing

Continuous all-optical deceleration and single-photon cooling of molecular beams

Bichromatic magneto-optical trapping forJ→J,J−1configurations

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