Journal of Modern Optics

Independent storage of the two components of an entangled state

Edward S. Fry, Thomas Walther

Published Jan 1, 2003• 1 citation

Abstract

We consider the use of solid rare gas matrices to separately store two atoms whose spin one-half nuclei are in an entangled state. We believe this is the first feasible example of the possibility of storing an entangled state. The two separated, entangled atoms are prepared by photodissociation of a diatomic molecule that is in a nuclear spin singlet state.

DOI: 10.1080/09500340308233565

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Journal of Modern Optics

Independent storage of the two components of an entangled state

Edward S. Fry, Thomas Walther

Published Jan 1, 2003• 1 citation

Publisher

Abstract

DOI: 10.1080/09500340308233565

Related papers

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Mikael Afzelius, Christoph Clausen, Imam Usmani +5 more

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Physical Review AMay 1, 19982 citations

We present photodissociation of ultracold long-range Rydberg molecules as a tool to characterize their electronic properties. We photoassociate

^{39}\mathrm{K}_{2} 37\phantom{\rule{0.16em}{0ex}}^{2}P

molecules with highly entangled electronic and nuclear spins of the two bound atoms and quantify the entanglement by projection of the molecular state onto noninteracting atoms using radio-frequency photodissociation. By comparison of experimental photodissociation rates with theoretical predictions, we further characterize the electronic and nuclear wave function of the photoassociated molecules. Based on the complete characterization of the formed long-range Rydberg molecules, we demonstrate a full hyperfine-spin flip of a free ground-state atom through the interaction with a Rydberg atom.

Ortho-para separations of

{}^{7}{\mathrm{Li}}_{2}

and

{}^{6}{\mathrm{Li}}_{2}

molecules were achieved by using a monochromatic laser beam to align atoms into a single nuclear spin state. This approach is unlike the cryogenic cooling technique, which has been successful only on very light molecules (such as

{\mathrm{H}}_{2}

and

{\mathrm{D}}_{2}

), which have large energy gaps between the lowest rotational states. The atoms were ``pumped into'' a single hyperfine Zeeman state with defined electron and nuclear spin orientations. The well-resolved rotational structures of the lithium molecules, as shown by laser-induced fluorescence spectra, revealed the enrichment of ortho-components over para-components. Using laser radiation with a power density of $\ensuremath{\sim}10{\mathrm{m}\mathrm{W}/\mathrm{c}\mathrm{m}}^{2}$ can increase the amount of ortho-components by a factor of 2 for

{}^{7}{\mathrm{Li}}_{2}

vapor and by a factor of 3 for

{}^{6}{\mathrm{Li}}_{2}

vapor on a time scale of milliseconds. This paper proposes a model to account for the experimental observations. These increases in the concentrations of ortho-components to para-components are explained by a combined effect of (i) a decrease in molecular density due to the electron spin orientation and (ii) a transfer of nuclear spin momenta from oriented atoms to molecules. The exchange reaction, ${\mathrm{Li}}^{\ensuremath{'}}{+\mathrm{L}\mathrm{i}}_{2}{\ensuremath{\rightarrow}\mathrm{Li}}_{3}{\ensuremath{\rightarrow}\mathrm{Li}}^{\ensuremath{'}}\mathrm{L}\mathrm{i}+\mathrm{L}\mathrm{i},$ appears to transfer the spin orientation from atoms to molecules. A substantial number of ortho-para separations can be achieved through multiple exchange collisions. Applications of this technique to other homonuclear diatomic molecules and polyatomic molecules with nuclear exchange symmetry are predicted.