182 research outputs found
Dispersive regime of the Jaynes-Cummings and Rabi lattice
Photon-based strongly-correlated lattice models like the Jaynes-Cummings and
Rabi lattices differ from their more conventional relatives like the
Bose-Hubbard model by the presence of an additional tunable parameter: the
frequency detuning between the pseudo-spin degree of freedom and the harmonic
mode frequency on each site. Whenever this detuning is large compared to
relevant coupling strengths, the system is said to be in the dispersive regime.
The physics of this regime is well-understood at the level of a single
Jaynes-Cummings or Rabi site. Here, we extend the theoretical description of
the dispersive regime to lattices with many sites, for both strong and
ultra-strong coupling. We discuss the nature and spatial range of the resulting
qubit-qubit and photon-photon coupling, demonstrate the emergence of photon-
pairing and squeezing, and illustrate our results by exact diagonalization of
the Rabi dimer.Comment: 22 pages, 7 figures, 1 table, Published by NJP, Focus Issues "Focus
on Quantum Microwave Field Effects in Superconducting Circuits
Measurement Protocol for the Entanglement Spectrum of Cold Atoms
Entanglement, and, in particular the entanglement spectrum, plays a major
role in characterizing many-body quantum systems. While there has been a surge
of theoretical works on the subject, no experimental measurement has been
performed to date because of the lack of an implementable measurement scheme.
Here, we propose a measurement protocol to access the entanglement spectrum of
many-body states in experiments with cold atoms in optical lattices. Our scheme
effectively performs a Ramsey spectroscopy of the entanglement Hamiltonian and
is based on the ability to produce several copies of the state under
investigation together with the possibility to perform a global swap gate
between two copies conditioned on the state of an auxiliary qubit. We show how
the required conditional swap gate can be implemented with cold atoms, either
by using Rydberg interactions or coupling the atoms to a cavity mode. We
illustrate these ideas on a simple (extended) Bose-Hubbard model where such a
measurement protocol reveals topological features of the Haldane phase
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