Physical Review A

Modified “δ-kick cooling” using magnetic field gradients

Stefan H. Myrskog, J. K. Fox, Han Seb Moon, J. B. Kim, Aephraim M. Steinberg

Published Apr 19, 2000• 27 citations

Abstract

We present an improved and simplified version of ``\ensuremath{\delta}-kick cooling.'' By application of a pulsed magnetic field, laser-cooled Rb atoms are cooled in one dimension, by a factor of 10 below the temperature of optical molasses. While phase-space density is conserved in this process, the method is more efficient than adiabatic expansion. We have achieved temperatures below 700 nK, but there is no fundamental limit to this cooling technique. The technique can also be used as an atom lens and as a spin-dependent probe. We show preliminary results suggesting interesting spin-temperature correlations within an optical molasses.

DOI: 10.1103/physreva.61.053412

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Physical Review A

Modified “δ-kick cooling” using magnetic field gradients

Stefan H. Myrskog, J. K. Fox, Han Seb Moon, J. B. Kim, Aephraim M. Steinberg

Published Apr 19, 2000• 27 citations

Publisher

Abstract

DOI: 10.1103/physreva.61.053412

Related papers

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We present progress towards a planned experiment on atomic tunneling of ultra-cold Rb atoms. As a first step in this experiment we present a realization of an improved form of "delta-kick cooling." By application of a pulsed magnetic field, laser cooled Rb atoms are further cooled by a factor of 10 (in 1-D) over the temperature out of molasses. Temperatures below 700 nK are observed. The technique can be used not only to cool without fundamental limit (but conserving phase-space density), but also to focus atoms, and as a spin-dependent probe.We present progress towards a planned experiment on atomic tunneling of ultra-cold Rb atoms. As a first step in this experiment we present a realization of an improved form of "delta-kick cooling." By application of a pulsed magnetic field, laser cooled Rb atoms are further cooled by a factor of 10 (in 1-D) over the temperature out of molasses. Temperatures below 700 nK are observed. The technique can be used not only to cool without fundamental limit (but conserving phase-space density), but also to focus atoms, and as a spin-dependent probe.

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Vladan Vuletić

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We describe cooling and trapping of both ${}^{85}$ Rb and ${}^{87}$ Rb in a range of magnetic fields up to 2.6 T. Atoms are injected from a low-field pyramidal magneto-optical trap and recaptured in a high-magnetic-field atom trap. The atoms are cooled and trapped by a six-beam optical molasses via the $5{S}_{1/2}|{m}_{I},{m}_{J}=$ 1/2$\ensuremath{\rangle}$$\ensuremath{\rightarrow}$ $5{P}_{3/2}|{m}_{I},{m}_{J}=$ 3/2$\ensuremath{\rangle}$ transition ( ${m}_{I}=$ 5/2 for ${}^{85}$ Rb and ${m}_{I}=$ 3/2 for ${}^{87}$ Rb). We study the trap fluorescence spectra, atom temperatures, density distributions, and lifetimes as a function of magnetic field and detuning parameters. The trap fluorescence spectra are both narrow and asymmetric, as is characteristic for laser cooling of atoms in an external trapping potential. The trap is modeled using a Monte Carlo trajectory simulation technique.We describe cooling and trapping of both ${}^{85}$Rb and ${}^{87}$Rb in a range of magnetic fields up to 2.6 T. Atoms are injected from a low-field pyramidal magneto-optical trap and recaptured in a high-magnetic-field atom trap. The atoms are cooled and trapped by a six-beam optical molasses via the $5{S}_{1/2}|{m}_{I},{m}_{J}=$ 1/2$\ensuremath{\rangle}$$\ensuremath{\rightarrow}$ $5{P}_{3/2}|{m}_{I},{m}_{J}=$ 3/2$\ensuremath{\rangle}$ transition (${m}_{I}=$ 5/2 for ${}^{85}$Rb and ${m}_{I}=$ 3/2 for ${}^{87}$Rb). We study the trap fluorescence spectra, atom temperatures, density distributions, and lifetimes as a function of magnetic field and detuning parameters. The trap fluorescence spectra are both narrow and asymmetric, as is characteristic for laser cooling of atoms in an external trapping potential. The trap is modeled using a Monte Carlo trajectory simulation technique.

Physical Review AAug 27, 20124 citations

{D}_{2}

line for laser cooling, but over a wide range extending to the

{D}_{1}

line. Via a combination of Sisyphus cooling followed by adiabatic expansion, we reach temperatures as low as 40 $\ensuremath{\mu}$K, which corresponds to atomic velocities a factor of 2.6 above the limit imposed by a single-photon recoil. Our method requires modest laser power at a frequency within reach of standard frequency-locking methods. It is largely insensitive to laser power, polarization and detuning, magnetic fields, and initial hyperfine populations. Our results suggest that optical molasses should be possible with all alkali-metal species.

We describe cooling and trapping of both

{}^{85}

Rb and

{}^{87}

Rb in a range of magnetic fields up to 2.6 T. Atoms are injected from a low-field pyramidal magneto-optical trap and recaptured in a high-magnetic-field atom trap. The atoms are cooled and trapped by a six-beam optical molasses via the

5{S}_{1/2}|{m}_{I},{m}_{J}=

1/2$\ensuremath{\rangle}$$\ensuremath{\rightarrow}$

5{P}_{3/2}|{m}_{I},{m}_{J}=

3/2$\ensuremath{\rangle}$ transition (

{m}_{I}=

5/2 for

{}^{85}

Rb and

{m}_{I}=

3/2 for

{}^{87}

Rb). We study the trap fluorescence spectra, atom temperatures, density distributions, and lifetimes as a function of magnetic field and detuning parameters. The trap fluorescence spectra are both narrow and asymmetric, as is characteristic for laser cooling of atoms in an external trapping potential. The trap is modeled using a Monte Carlo trajectory simulation technique.