Quantum phase transitions of atom-molecule Bose mixtures in a double-well potential.
The ground state and spectral properties of Bose gases in double-well potentials are studied in two different scenarios: (i) an interacting atomic Bose gas, and (ii) a mixture of an atomic gas interacting with diatomic molecules. A ground state second-order quantum phase transition is observed in both scenarios. For large attractive values of the atom-atom interaction, the ground state is degenerate. For repulsive and small attractive interaction, the ground state is not degenerate and is well approximated by a boson coherent state. Both systems depict an excited state quantum phase transition. In both cases, a critical energy separates a region in which all the energy levels are degenerate in pairs, from another region in which there are no degeneracies. For the atomic system, the critical point displays a singularity in the density of states, whereas this behavior is largely smoothed for the mixed atom-molecule system.
Departamento de Física Aplicada I and GISC, Universidad Complutense de Madrid, 28040 Madrid, Spain.
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A
Relaño
Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid, Spain.
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J
Dukelsky
Departamento de Física Aplicada III, Universidad de Sevilla, Sevilla, Spain.
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P
Pérez-Fernández
Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla and Unidad Asociada to IEM (CSIC) Madrid, Spain.
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JM
Arias