Sideband laser cooling using stimulated Raman transitions is performed on trapped cesium atoms. The confinement is produced by a far–off-resonance dipole trap consisting of two crossed YAG beams which, by interference, create a one-dimensional optical lattice. In a pure intensity lattice, we measure a 1D temperature of T = 6 μK corresponding to a mean quantum vibrational number of about nv = 0.75. In a polarization gradient lattice, the final temperature is T = 3.6 μK corresponding to nv 2.4.Sideband laser cooling using stimulated Raman transitions is performed on trapped cesium atoms. The confinement is produced by a far–off-resonance dipole trap consisting of two crossed YAG beams which, by interference, create a one-dimensional optical lattice. In a pure intensity lattice, we measure a 1D temperature of T = 6 μK corresponding to a mean quantum vibrational number of about nv = 0.75. In a polarization gradient lattice, the final temperature is T = 3.6 μK corresponding to nv 2.4.

European Quantum Electronics Conference (EQEC)Aug 24, 20051 citation

Raman sideband cooling of rubidium atoms in optical lattice

Chunhua Wei, Shuhua Yan

We develop a simple and practical scheme to apply sideband cooling to a cloud of rubidium atoms. A sample containing 4 × 10 70 87 Rb is trapped in a far red detuned optical lattice. Through optimizing the relevant parameters, i.e., laser detuning, magnetic field, polarization, and duration time, a temperature around 1.5 μK and phase space density close to 1/500 are achieved. Compared with polarization gradient cooling, the temperature decreases by around one order of magnitude. This technique could be used in high precision measurement such as atomic clocks and atom interferometer. It could also serve as a precooling means before evaporation cooling in a dipole trap, and may be a promising method of achieving quantum degeneracy with purely optical means.We develop a simple and practical scheme to apply sideband cooling to a cloud of rubidium atoms. A sample containing 4 × 10 70 87 Rb is trapped in a far red detuned optical lattice. Through optimizing the relevant parameters, i.e., laser detuning, magnetic field, polarization, and duration time, a temperature around 1.5 μK and phase space density close to 1/500 are achieved. Compared with polarization gradient cooling, the temperature decreases by around one order of magnitude. This technique could be used in high precision measurement such as atomic clocks and atom interferometer. It could also serve as a precooling means before evaporation cooling in a dipole trap, and may be a promising method of achieving quantum degeneracy with purely optical means.

Chinese Physics BAug 1, 20172 citations

Degenerate Raman Sideband Cooling of Trapped Cesium Atoms at Very High Atomic Densities

Vladan Vuletić, Cheng Chin, Andrew J. Kerman +1 more

We trap ${10}^{7}$ cesium atoms in a far red detuned 1D optical lattice. With degenerate Raman sideband cooling we achieve a vibrational ground state population of 80% for the steep trapping direction. Collisional coupling enables us to cool the spin-polarized gas in 3D without loss of atoms to a peak phase space density of $1/180$ at a mean temperature of $2.8\ensuremath{\mu}\mathrm{K}$ and a density of $1.4\ifmmode\times\else\texttimes\fi{}{10}^{13}{\mathrm{cm}}^{\ensuremath{-}3}$.We trap ${10}^{7}$ cesium atoms in a far red detuned 1D optical lattice. With degenerate Raman sideband cooling we achieve a vibrational ground state population of 80% for the steep trapping direction. Collisional coupling enables us to cool the spin-polarized gas in 3D without loss of atoms to a peak phase space density of $1/180$ at a mean temperature of $2.8\ensuremath{\mu}\mathrm{K}$ and a density of $1.4\ifmmode\times\else\texttimes\fi{}{10}^{13}{\mathrm{cm}}^{\ensuremath{-}3}$.

Physical Review LettersDec 28, 1998213 citations

Quantum state preparation in an optical lattice

S. E. Hamann

This dissertation reports on quantum state preparation of cesium atoms in a two-dimensional optical lattice, by resolved-sideband Raman cooling. An optical lattice is a periodic potential produced by the light shift interaction between an atom and light field. Laser cooled atoms can become strongly localized about the bottom of potential wells in an optical lattice, where they occupy a discrete spectrum of bound vibrational energy levels. The distribution over vibrational levels of atoms in the lattice is characterized by the mean vibrational excitation, n . In an optical lattice, absorption and emission of photons from lattice beams causes n to increase in time. This source of heating is always present, but its rate can be greatly reduced in a lattice detuned far from the atomic resonance. Sideband cooling is an efficient means of transferring atoms from higher into lower-lying vibrational levels and, thus, it reduces n for the ensemble. If the sideband cooling rate is much greater than the heating rate, then n approaches zero and virtually all atoms are in the lowest vibrational level in their potential wells. Our sideband cooling scheme involves stimulated Raman transitions between bound states in the potential wells of a pair of magnetic sublevels, followed by optical pumping, for a net loss of one quantum of vibration per cooling cycle. The process accumulates 98% of atoms in the ground vibrational level of a potential well associated with a single Zeeman substate. Each atom in the lattice is then very close to a pure state. For two-dimensional lattice with sideband cooling we find nx≈ny≈0.008 &parl0;16&parr0; . Various issues related to state preparation and sideband cooling are also discussed in the context of a one dimensional lin ⊥ lin optical lattice. These include improvement of laser cooling in a near resonance lattice by application of weak magnetic fields, transfer of atoms from near into far off-resonance lattices, and heating rates in far off-resonance lattices.This dissertation reports on quantum state preparation of cesium atoms in a two-dimensional optical lattice, by resolved-sideband Raman cooling. An optical lattice is a periodic potential produced by the light shift interaction between an atom and light field. Laser cooled atoms can become strongly localized about the bottom of potential wells in an optical lattice, where they occupy a discrete spectrum of bound vibrational energy levels. The distribution over vibrational levels of atoms in the lattice is characterized by the mean vibrational excitation, n . In an optical lattice, absorption and emission of photons from lattice beams causes n to increase in time. This source of heating is always present, but its rate can be greatly reduced in a lattice detuned far from the atomic resonance. Sideband cooling is an efficient means of transferring atoms from higher into lower-lying vibrational levels and, thus, it reduces n for the ensemble. If the sideband cooling rate is much greater than the heating rate, then n approaches zero and virtually all atoms are in the lowest vibrational level in their potential wells. Our sideband cooling scheme involves stimulated Raman transitions between bound states in the potential wells of a pair of magnetic sublevels, followed by optical pumping, for a net loss of one quantum of vibration per cooling cycle. The process accumulates 98% of atoms in the ground vibrational level of a potential well associated with a single Zeeman substate. Each atom in the lattice is then very close to a pure state. For two-dimensional lattice with sideband cooling we find nx≈ny≈0.008 &parl0;16&parr0; . Various issues related to state preparation and sideband cooling are also discussed in the context of a one dimensional lin ⊥ lin optical lattice. These include improvement of laser cooling in a near resonance lattice by application of weak magnetic fields, transfer of atoms from near into far off-resonance lattices, and heating rates in far off-resonance lattices.

Jan 1, 19981 citation

Cesium gas strongly confined in one dimension: Sideband cooling and collisional properties

Isabelle Bouchoule, M. Morinaga, Ch Salomon +1 more

We study one-dimensional (1D) sideband cooling of cesium atoms strongly confined in a far-detuned optical lattice. The Lamb-Dicke regime is achieved in the lattice direction whereas the transverse confinement is much weaker. The employed sideband cooling method, first studied by Vuleti\ifmmode \acute{c}\else \'{c}\fi{} et al., uses Raman transitions between Zeeman levels and produces a spin-polarized sample. We present a detailed study of this cooling method and investigate the role of elastic collisions in the system. We accumulate 83(5)% of the atoms in the vibrational ground state of the strongly confined motion, and elastic collisions cool the transverse motion to a temperature of $2.8\ensuremath{\mu}\mathrm{K}=0.7\ensuremath{\Elzxh}{\ensuremath{\omega}}_{\mathrm{osc}}{/k}_{B},$ where ${\ensuremath{\omega}}_{\mathrm{osc}}$ is the oscillation frequency in the strongly confined direction. The sample then approaches the regime of a quasi-2D cold gas. We analyze the limits of this cooling method and propose a dynamical change of the trapping potential as a mean of cooling the atomic sample to still lower temperatures. Measurements of the rate of thermalization between the weakly and strongly confined degrees of freedom are compatible with the zero-energy scattering resonance observed previously in weak 3D traps. For the explored temperature range the measurements agree with recent calculations of quasi-2D collisions. Transparent analytical models reproduce the expected behavior for ${k}_{B}T\ensuremath{\gg}\ensuremath{\Elzxh}{\ensuremath{\omega}}_{\mathrm{osc}}$ and also for ${k}_{B}T\ensuremath{\ll}\ensuremath{\Elzxh}{\ensuremath{\omega}}_{\mathrm{osc}}$ where the 2D features are prominent.We study one-dimensional (1D) sideband cooling of cesium atoms strongly confined in a far-detuned optical lattice. The Lamb-Dicke regime is achieved in the lattice direction whereas the transverse confinement is much weaker. The employed sideband cooling method, first studied by Vuleti\ifmmode \acute{c}\else \'{c}\fi{} et al., uses Raman transitions between Zeeman levels and produces a spin-polarized sample. We present a detailed study of this cooling method and investigate the role of elastic collisions in the system. We accumulate 83(5)% of the atoms in the vibrational ground state of the strongly confined motion, and elastic collisions cool the transverse motion to a temperature of $2.8\ensuremath{\mu}\mathrm{K}=0.7\ensuremath{\Elzxh}{\ensuremath{\omega}}_{\mathrm{osc}}{/k}_{B},$ where ${\ensuremath{\omega}}_{\mathrm{osc}}$ is the oscillation frequency in the strongly confined direction. The sample then approaches the regime of a quasi-2D cold gas. We analyze the limits of this cooling method and propose a dynamical change of the trapping potential as a mean of cooling the atomic sample to still lower temperatures. Measurements of the rate of thermalization between the weakly and strongly confined degrees of freedom are compatible with the zero-energy scattering resonance observed previously in weak 3D traps. For the explored temperature range the measurements agree with recent calculations of quasi-2D collisions. Transparent analytical models reproduce the expected behavior for ${k}_{B}T\ensuremath{\gg}\ensuremath{\Elzxh}{\ensuremath{\omega}}_{\mathrm{osc}}$ and also for ${k}_{B}T\ensuremath{\ll}\ensuremath{\Elzxh}{\ensuremath{\omega}}_{\mathrm{osc}}$ where the 2D features are prominent.

arXiv:quant-ph/0106032Physical Review AFeb 1, 200216 citations

Stimulated Raman transitions for cooling atoms in an optical dipole trap

Joseph D. Miller, Robert A. Cline, Daniel J. Heinzen

Optical dipole traps can provide strong, state-independent confinement of atoms. Unfortunately, the spatially dependent light shifts of optical transitions in dipole traps can interfere with conventional laser cooling techniques. These limitations may be overcome by cooling trapped atoms with stimulated Raman transitions. In particular, the lights shifts of ground state sublevels can be equal, so that the Raman cooling transition is unperturbed. Cooling in the sideband limit, to the quantum ground state of motion, should be possible. We have confined {sup 85}Rb atoms in a far-detuned optical dipole trap, and indirectly measured extremely low heating rates of the trapped atoms. We have also driven velocity-sensitive stimulated Raman transitions of the trapped atoms. The high resolution of these stimulated Raman resonances should allow us to resolve the motional sidebands and to directly cool the trapped atoms.Optical dipole traps can provide strong, state-independent confinement of atoms. Unfortunately, the spatially dependent light shifts of optical transitions in dipole traps can interfere with conventional laser cooling techniques. These limitations may be overcome by cooling trapped atoms with stimulated Raman transitions. In particular, the lights shifts of ground state sublevels can be equal, so that the Raman cooling transition is unperturbed. Cooling in the sideband limit, to the quantum ground state of motion, should be possible. We have confined {sup 85}Rb atoms in a far-detuned optical dipole trap, and indirectly measured extremely low heating rates of the trapped atoms. We have also driven velocity-sensitive stimulated Raman transitions of the trapped atoms. The high resolution of these stimulated Raman resonances should allow us to resolve the motional sidebands and to directly cool the trapped atoms.

Bulletin of the American Physical SocietyMay 1, 19930 citations

We trap

{10}^{7}

cesium atoms in a far red detuned 1D optical lattice. With degenerate Raman sideband cooling we achieve a vibrational ground state population of 80% for the steep trapping direction. Collisional coupling enables us to cool the spin-polarized gas in 3D without loss of atoms to a peak phase space density of

1/180

at a mean temperature of $2.8\ensuremath{\mu}\mathrm{K}$ and a density of $1.4\ifmmode\times\else\texttimes\fi{}{10}^{13}{\mathrm{cm}}^{\ensuremath{-}3}$.