Quantum-Atom Optics Downunder (QAO)

Resonant Einstein-de Haas effect in a rubidium condensate

Krzysztof Gawryluk, Mirosław Brewczyk, Kai Bongs, Mariusz Gajda

Published Jan 1, 2007• 2 citations

Abstract

We numerically investigate a condensate of 87Rb atoms in an F=1 hyperfine state confined in an optical dipole trap. Assuming the magnetic moments of all atoms are initially aligned along the magnetic field we observe, after the field's direction is reversed, a transfer of atoms to other Zeeman states. Such transfer is allowed by the dipolar interaction. The atoms in m_F=0, −1 start to circulate around the center of the trap. We find resonances which amplify this phenomenon making it observable even in rubidium condensates.

DOI: 10.1364/qao.2007.qme2

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Quantum-Atom Optics Downunder (QAO)

Resonant Einstein-de Haas effect in a rubidium condensate

Krzysztof Gawryluk, Mirosław Brewczyk, Kai Bongs, Mariusz Gajda

Published Jan 1, 2007• 2 citations

Publisher

Abstract

DOI: 10.1364/qao.2007.qme2

Related papers

Einstein-de Haas effect for a $^{87}$ Rb atoms condensateEinstein-de Haas effect for a $^{87}$Rb atoms condensate

Krzysztof Gawryluk, Mirosław Brewczyk, Kai Bongs +1 more

We consider a condensate of $^{87}$ Rb atoms in an F=1 hyperfine state confined in an optical dipole trap. Assuming the magnetic moments of all atoms are initially aligned along the magnetic field we observe, after the field's direction is reversed, a transfer of atoms to other Zeeman states due to the dipolar interaction. We find that there exist resonances which amplify the effect of dipolar interaction. When the resonance condition is satisfied the transfer of atoms to $m_F=0,-1$ states might be of the order of the initial population of $m_F=1$ component. While changing the magnetic moments during the transfer, the atomsacquire an orbital angular momentum and start to circulate around the center of the trap. This is a realization of the famous Einstein-de Haas effect in systems of cold gases. Due to the dipolar resonances, it becomes possible to observe this phenomenon even in a condensate of $^{87}$ Rb (F=1) atoms that have very small magnetic moment.We consider a condensate of $^{87}$Rb atoms in an F=1 hyperfine state confined in an optical dipole trap. Assuming the magnetic moments of all atoms are initially aligned along the magnetic field we observe, after the field's direction is reversed, a transfer of atoms to other Zeeman states due to the dipolar interaction. We find that there exist resonances which amplify the effect of dipolar interaction. When the resonance condition is satisfied the transfer of atoms to $m_F=0,-1$ states might be of the order of the initial population of $m_F=1$ component. While changing the magnetic moments during the transfer, the atomsacquire an orbital angular momentum and start to circulate around the center of the trap. This is a realization of the famous Einstein-de Haas effect in systems of cold gases. Due to the dipolar resonances, it becomes possible to observe this phenomenon even in a condensate of $^{87}$Rb (F=1) atoms that have very small magnetic moment.

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Optimization as a route towards observing the Einstein-de Haas effect in a rubidium condensate

Tomasz Świsłocki, Mariusz Gajda, Mirosław Brewczyk

The main obstacle in experimental realization of the Einstein-de Haas effect in a Bose-Einstein condensate is necessity of a very precise control of the extremely small (of the order of tens of $μ$ G) external magnetic field. In this paper we numerically study the response of a rubidium condensate to an optimized time-dependent magnetic field. We find a significant transfer of atoms from the initial maximally polarized state to the next Zeeman component at magnetic fields of the order of tens of milligauss. We propose an experiment in which such an optimization scheme could enable the observation of the Einstein-de Haas effect in a rubidium atom condensate.The main obstacle in experimental realization of the Einstein-de Haas effect in a Bose-Einstein condensate is necessity of a very precise control of the extremely small (of the order of tens of $μ$G) external magnetic field. In this paper we numerically study the response of a rubidium condensate to an optimized time-dependent magnetic field. We find a significant transfer of atoms from the initial maximally polarized state to the next Zeeman component at magnetic fields of the order of tens of milligauss. We propose an experiment in which such an optimization scheme could enable the observation of the Einstein-de Haas effect in a rubidium atom condensate.

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Observing the Einstein–de Haas Effect with Atoms in an Optical Lattice

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Physical Review LettersOct 10, 200715 citations

Einstein-de Haas effect for a

^{87}

Rb atoms condensate

We consider a condensate of

^{87}

Rb atoms in an F=1 hyperfine state confined in an optical dipole trap. Assuming the magnetic moments of all atoms are initially aligned along the magnetic field we observe, after the field's direction is reversed, a transfer of atoms to other Zeeman states due to the dipolar interaction. We find that there exist resonances which amplify the effect of dipolar interaction. When the resonance condition is satisfied the transfer of atoms to

m_F=0,-1

states might be of the order of the initial population of

m_F=1

component. While changing the magnetic moments during the transfer, the atomsacquire an orbital angular momentum and start to circulate around the center of the trap. This is a realization of the famous Einstein-de Haas effect in systems of cold gases. Due to the dipolar resonances, it becomes possible to observe this phenomenon even in a condensate of

^{87}

Rb (F=1) atoms that have very small magnetic moment.

We theoretically study a spinor condensate of

^{87}\mathrm{Rb}

atoms in a

F=1

hyperfine state confined in an optical dipole trap. Putting initially all atoms in an

{m}_{F}=1

, component we observe a significant transfer of atoms to other, initially empty Zeeman states exclusively due to dipolar forces. Because of conservation of a total angular momentum the atoms going to other Zeeman components acquire an orbital angular momentum and circulate around the center of the trap. This is a realization of the Einstein-de Haas effect in a system of cold gases. We show that the transfer of atoms via dipolar interactions is possible only when the energies of the initial and the final sates are equal. This condition can be fulfilled utilizing a resonant external magnetic field, which tunes energies of involved states via the linear Zeeman effect. We found that there are many final states of different spatial density, which can be tuned selectively to the initial state. We show a simple model explaining high selectivity and controllability of weak dipolar interactions in the condensate of

^{87}\mathrm{Rb}

atoms.

The main obstacle in experimental realization of the Einstein-de Haas effect in a Bose-Einstein condensate is necessity of a very precise control of the extremely small (of the order of tens of

μ

G) external magnetic field. In this paper we numerically study the response of a rubidium condensate to an optimized time-dependent magnetic field. We find a significant transfer of atoms from the initial maximally polarized state to the next Zeeman component at magnetic fields of the order of tens of milligauss. We propose an experiment in which such an optimization scheme could enable the observation of the Einstein-de Haas effect in a rubidium atom condensate.