A continuous source of spin-polarized cold atoms

We propose a method to generate a source of spin-polarized cold atoms which are continuously extracted and guided from a magneto-optical trap using an atom-diode effect. We show that it is possible to create a pipe-like potential by overlapping two optical beams coupled with the two transitions of a three-level system in a ladder configuration. With alkali-metal atoms, and in particular with ${}^{87}$ Rb, a proper choice of transitions enables both the potential generation and optical pumping, thus polarizing the sample in a given Zeeman state. We extend the Dalibard and Cohen-Tannoudji dressed-atom model of radiative forces to the case of a three-level system. We derive expressions for the average force and the different sources of momentum diffusion in the resonant, nonperturbative regime. We show using numerical simulations that a significant fraction of the atoms initially loaded can be guided over several centimeters with output velocities of a few meters per second. This would produce a collimated continuous source of slow spin-polarized atoms suitable for atom interferometry.We propose a method to generate a source of spin-polarized cold atoms which are continuously extracted and guided from a magneto-optical trap using an atom-diode effect. We show that it is possible to create a pipe-like potential by overlapping two optical beams coupled with the two transitions of a three-level system in a ladder configuration. With alkali-metal atoms, and in particular with ${}^{87}$Rb, a proper choice of transitions enables both the potential generation and optical pumping, thus polarizing the sample in a given Zeeman state. We extend the Dalibard and Cohen-Tannoudji dressed-atom model of radiative forces to the case of a three-level system. We derive expressions for the average force and the different sources of momentum diffusion in the resonant, nonperturbative regime. We show using numerical simulations that a significant fraction of the atoms initially loaded can be guided over several centimeters with output velocities of a few meters per second. This would produce a collimated continuous source of slow spin-polarized atoms suitable for atom interferometry.

arXiv:1301.4439Physical Review AMar 8, 20136 citations

A continuous source of cold spin-polarized cold atoms

Thomas Vanderbruggen, Silvana Palacios, N. Martinez +1 more

Summary form only given. We propose a new method to produce a continuous source of spin-polarized cold atoms which are all-optically guided after their extraction from a magneto-optical trap (MOT), as depicted in Fig. 1 (a). The techniques combines several physical effects and relies on light-shift engineering [Fig. 1 (b)], implemented using two coaxially overlapped optical beams each one driving a given transition of a three-level atom in a ladder configuration (Ξ-system). In a well chosen configuration, the light-shift creates a state-dependent potential which implements the atom-diode [1] responsible for the continuous extraction of the atoms from a MOT into an all-optical guide.We performed a theoretical study by extending the Dalibard and Cohen-Tannoudji dressed-atom model [2] to the case of a doubly-driven Ξ-system. We analysed and quantified the dipole forces and the various sources of momentum diffusion in the resonant, non-perturbative, regime. In particular, from the Markovian evolution of the internal state, we obtain a general formula for the diffusion coefficient associated with the dipole force fluctuation. We proposed and studied in detail the implementation of the method for 87Rb atoms. We show that, using σ+polarized fields driving the transitions 52S1/2 → 52P3/2 and 52P3/2 → 42D5/2 at 780 nm and 1529 nm respectively, a closed Ξ-system can be isolated within the complicated structure of 87Rb. Moreover, with this choice of transitions, the atoms will be optically pumped in a given Zeeman sub-state thus polarizing the atomic sample. The theoretical results have then been used in a numerical simulation of Langevin-like equations [Fig. 1 (c)] to estimate the performance of the system. From the simulation of 10000 trajectories, we show that a large fraction of the atoms (~ 64%) is guided over at least 5 cm, the mean velocity at this distance being 5.6 m/s with a dispersion of 2.2 m/s. This guided distance allows to deliver the atoms inside a magnetic shield that cancels the continuously operated MOT magnetic field. The proposed method thus creates a continuous source of guided spin-polarized cold atoms. Such a source can be of particular interest for atom interferometry.Summary form only given. We propose a new method to produce a continuous source of spin-polarized cold atoms which are all-optically guided after their extraction from a magneto-optical trap (MOT), as depicted in Fig. 1 (a). The techniques combines several physical effects and relies on light-shift engineering [Fig. 1 (b)], implemented using two coaxially overlapped optical beams each one driving a given transition of a three-level atom in a ladder configuration (Ξ-system). In a well chosen configuration, the light-shift creates a state-dependent potential which implements the atom-diode [1] responsible for the continuous extraction of the atoms from a MOT into an all-optical guide.We performed a theoretical study by extending the Dalibard and Cohen-Tannoudji dressed-atom model [2] to the case of a doubly-driven Ξ-system. We analysed and quantified the dipole forces and the various sources of momentum diffusion in the resonant, non-perturbative, regime. In particular, from the Markovian evolution of the internal state, we obtain a general formula for the diffusion coefficient associated with the dipole force fluctuation. We proposed and studied in detail the implementation of the method for 87Rb atoms. We show that, using σ+polarized fields driving the transitions 52S1/2 → 52P3/2 and 52P3/2 → 42D5/2 at 780 nm and 1529 nm respectively, a closed Ξ-system can be isolated within the complicated structure of 87Rb. Moreover, with this choice of transitions, the atoms will be optically pumped in a given Zeeman sub-state thus polarizing the atomic sample. The theoretical results have then been used in a numerical simulation of Langevin-like equations [Fig. 1 (c)] to estimate the performance of the system. From the simulation of 10000 trajectories, we show that a large fraction of the atoms (~ 64%) is guided over at least 5 cm, the mean velocity at this distance being 5.6 m/s with a dispersion of 2.2 m/s. This guided distance allows to deliver the atoms inside a magnetic shield that cancels the continuously operated MOT magnetic field. The proposed method thus creates a continuous source of guided spin-polarized cold atoms. Such a source can be of particular interest for atom interferometry.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)May 1, 20130 citations

Spin-Polarized Atoms

Galina A. Nemova

SPIE eBooksNov 6, 20190 citations

Decoherence and dynamics in continuous 3D-cooled atom interferometry

Adam T. Black, Jonathan M. Kwolek, Charles Fancher +1 more

We study decoherence in continuously cooled atom interferometers by performing Raman-Ramsey fringe measurements in a continuous beam of 3D-sub-Doppler-cooled rubidium atoms. The atom beam is produced by a two-stage cold atom source that is designed to mitigate the decoherence of atomic interference caused by cooling induced fluorescence. The atom beam source produces a collimated beam of over 109 atoms/s that is cooled by polarization gradient cooling to temperatures as low as 14 µK. We infer the potential performance of this atom beam source in a cold-atom gyroscope and use numerical models of motion in 6 degrees of freedom to study the expected performance on dynamic platforms.We study decoherence in continuously cooled atom interferometers by performing Raman-Ramsey fringe measurements in a continuous beam of 3D-sub-Doppler-cooled rubidium atoms. The atom beam is produced by a two-stage cold atom source that is designed to mitigate the decoherence of atomic interference caused by cooling induced fluorescence. The atom beam source produces a collimated beam of over 109 atoms/s that is cooled by polarization gradient cooling to temperatures as low as 14 µK. We infer the potential performance of this atom beam source in a cold-atom gyroscope and use numerical models of motion in 6 degrees of freedom to study the expected performance on dynamic platforms.

Optical and Quantum Sensing and Precision Metrology IIFeb 25, 20207 citations

{}^{87}

Rb, a proper choice of transitions enables both the potential generation and optical pumping, thus polarizing the sample in a given Zeeman state. We extend the Dalibard and Cohen-Tannoudji dressed-atom model of radiative forces to the case of a three-level system. We derive expressions for the average force and the different sources of momentum diffusion in the resonant, nonperturbative regime. We show using numerical simulations that a significant fraction of the atoms initially loaded can be guided over several centimeters with output velocities of a few meters per second. This would produce a collimated continuous source of slow spin-polarized atoms suitable for atom interferometry.