392 research outputs found
Reproducing spin lattice models in strongly coupled atom-cavity systems
In an array of coupled cavities where the cavities are doped with an atomic
V-system, and the two excited levels couple to cavity photons of different
polarizations, we show how to construct various spin models employed in
characterizing phenomena in condensed matter physics, such as the spin-1/2
Ising, XX, Heisenberg, and XXZ models. The ability to construct networks of
arbitrary geometry also allows for the simulation of topological effects. By
tuning the number of excitations present, the dimension of the spin to be
simulated can be controlled, and mixtures of different spin types produced. The
facility of single-site addressing, the use of only the natural hopping photon
dynamics without external fields, and the recent experimental advances towards
strong coupling, makes the prospect of using these arrays as efficient quantum
simulators promising.Comment: 4 pages, 3 figures. v3: References adde
Simulation of high-spin Heisenberg models in coupled cavities
We propose a scheme to realize the Heisenberg model of any spin in an
arbitrary array of coupled cavities. Our scheme is based on a fixed number of
atoms confined in each cavity and collectively applied constant laser fields,
and is in a regime where both atomic and cavity excitations are suppressed. It
is shown that as well as optically controlling the effective spin Hamiltonian,
it is also possible to engineer the magnitude of the spin. Our scheme would
open up an unprecedented way to simulate otherwise intractable high-spin
problems in many-body physics.Comment: 4 pages, 2 figure
Beyond mean-field bistability in driven-dissipative lattices: bunching-antibunching transition and quantum simulation
In the present work we investigate the existence of multiple nonequilibrium
steady states in a coherently driven XY lattice of dissipative two-level
systems. A commonly used mean-field ansatz, in which spatial correlations are
neglected, predicts a bistable behavior with a sharp shift between low- and
high-density states. In contrast one-dimensional matrix product methods reveal
these effects to be artifacts of the mean-field approach, with both
disappearing once correlations are taken fully into account. Instead, a
bunching-antibunching transition emerges. This indicates that alternative
approaches should be considered for higher spatial dimensions, where classical
simulations are currently infeasible. Thus we propose a circuit QED quantum
simulator implementable with current technology to enable an experimental
investigation of the model considered
Spinons and Holons with Polarized Photons in a Nonlinear Waveguide
We show that the spin-charge separation predicted for correlated fermions in
one dimension, could be observed using polarized photons propagating in a
nonlinear optical waveguide. Using coherent control techniques and employing a
cold atom ensemble interacting with the photons, large nonlinearities in the
single photon level can be achieved. We show that the latter can allow for the
simulation of a strongly interacting gas, which is made of stationary
dark-state polaritons of two species and then shown to form a Luttinger liquid
of effective fermions for the right regime of interactions. The system can be
tuned optically to the relevant regime where the spin-charge separation is
expected to occur. The characteristic features of the separation as
demonstrated in the different spin and charge densities and velocities can be
efficiently detected via optical measurements of the emitted photons with
current optical technologies.Comment: To appear in New Journal of Physic
Steady state entanglement between hybrid light-matter qubits
We study the case of two polaritonic qubits localized in two separate
cavities coupled by a fiber/additional cavity. We show that surprisingly
enough, even a coherent classical pump in the intermediate cavity/fiber can
lead to the creation of entanglement between the two ends in the steady state.
The stationary nature of this entanglement and its survival under dissipation
opens possibilities for its production under realistic laboratory conditions.
To facilitate the verification of the entanglement in an experiment we also
construct the relevant entanglement witness measurable by accessing only a few
local variables of each polaritonic qubit.Comment: 8 pages, 3 figure
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