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arXiv · 1111.1617

Double symmetry breaking and 2D quantum phase diagram in spin-boson systems

Pierre Nataf·Alexandre Baksic·Cristiano Ciuti
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Abstract

The quantum ground state properties of two independent chains of spins (two-levels systems) interacting with the same bosonic field are theoretically investigated. Each chain is coupled to a different quadrature of the field, leading to two independent symmetry breakings for increasing values of the two spin-boson interaction constants $\Omega_C$ and $\Omega_I$. A phase diagram is provided in the plane ($\Omega_C$,$\Omega_I$) with 4 different phases that can be characterized by the complex bosonic coherence of the ground states and can be manipulated via non-abelian Berry effects. In particular, when $\Omega_C$ and $\Omega_I$ are both larger than two critical values, the fundamental subspace has a four-fold degeneracy. Possible implementations in superconducting or atomic systems are discussed.

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Pierre Nataf, Alexandre Baksic, Cristiano Ciuti. 2011-11-07. Double symmetry breaking and 2D quantum phase diagram in spin-boson systems. https://doi.org/10.1103/physreva.86.013832

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