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Quantum Electronics and Laser Science Conference

Effects of magnetic fields on magnetic grating free induction decay (MGFID) in a cold Rb vapor

S. B. Cahn, Anantharaman Kumarakrishnan, Unyob Shim, Tycho Sleator

Published Jun 2, 1996• 0 citations
OpenAlex

Abstract

Summary form only given. The magnetic grating free induction decay (MGFID) may be produced in a sample of room temperature (300 K) /sup 35/Rb, demonstrating the coherence between alternate magnetic sublevels. The decay rate of this coherence is dominated by the dispersal of the atoms and proportional to the most probable velocity u of the atoms. By slowing and confining the atoms in a magnetooptic trap, the decay rate may be reduced by several orders of magnitude.

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Collisional revival of magnetic grating free-induction decay

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Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.

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We have developed a theoretical description of the evolution of ground state coherences between magnetic sublevels in Rb vapor in the presence of a magnetic field along an arbitrary direction. This formalism uses a rotation matrix approach to describe the evolution of coherences created by two traveling wave laser pulses with orthogonal polarizations. The effect of a magnetic field can be described as a time-dependent rotation of the atomic system about the quantization axis. Predictions based on this theoretical formalism for the functional form of Larmor oscillations in a magnetic field are studied using a coherent transient effect known as magnetic grating free induction decay (MGFID) using room temperature vapor and laser cooled atoms. We find the theoretical predictions to be in excellent agreement with data. The velocity distribution of the cold sample measured from the dephasing time of the MGFID in the absence of magnetic fields is in agreement with the sample temperature obtained by imaging the ballistic expansion of the trapped cloud. By using rate equations to model atomic coherences, it is also possible to predict the evolution of magnetic grating echoes (MGE) in a magnetic field. We compare these predictions with experiments from cold atoms and discuss applications of the MGFID and MGE that relate to a precision measurement of the atomic $g$ factor ratio using $^{85}\mathrm{Rb}$ and $^{87}\mathrm{Rb}$ isotopes.

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Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.

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Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.

Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)•Jan 1, 1997•0 citations

Collisional revival of magnetic grating free-induction decay

Unyob Shim, Anantharaman Kumarakrishnan, S.B. Cahn +1 more

Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.

Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)•Jan 1, 1997•0 citations
Summary form only given. The magnetic grating free induction decay (MGFID) may be produced in a sample of room temperature (300 K) /sup 35/Rb, demonstrating the coherence between alternate magnetic sublevels. The decay rate of this coherence is dominated by the dispersal of the atoms and proportional to the most probable velocity u of the atoms. By slowing and confining the atoms in a magnetooptic trap, the decay rate may be reduced by several orders of magnitude.
Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.
Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.
We have developed a theoretical description of the evolution of ground state coherences between magnetic sublevels in Rb vapor in the presence of a magnetic field along an arbitrary direction. This formalism uses a rotation matrix approach to describe the evolution of coherences created by two traveling wave laser pulses with orthogonal polarizations. The effect of a magnetic field can be described as a time-dependent rotation of the atomic system about the quantization axis. Predictions based on this theoretical formalism for the functional form of Larmor oscillations in a magnetic field are studied using a coherent transient effect known as magnetic grating free induction decay (MGFID) using room temperature vapor and laser cooled atoms. We find the theoretical predictions to be in excellent agreement with data. The velocity distribution of the cold sample measured from the dephasing time of the MGFID in the absence of magnetic fields is in agreement with the sample temperature obtained by imaging the ballistic expansion of the trapped cloud. By using rate equations to model atomic coherences, it is also possible to predict the evolution of magnetic grating echoes (MGE) in a magnetic field. We compare these predictions with experiments from cold atoms and discuss applications of the MGFID and MGE that relate to a precision measurement of the atomic ggg factor ratio using 85Rb^{85}\mathrm{Rb}85Rb and 87Rb^{87}\mathrm{Rb}87Rb isotopes.
Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.
Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.
Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.