17,015 research outputs found
Synchronized Switching in a Josephson Junction Crystal
We consider a superconducting coplanar waveguide resonator where the central
conductor is interrupted by a series of uniformly spaced Josephson junctions.
The device forms an extended medium that is optically nonlinear on the single
photon level with normal modes that inherit the full nonlinearity of the
junctions but are nonetheless accessible via the resonator ports. For specific
plasma frequencies of the junctions a set of normal modes clusters in a narrow
band and eventually become entirely degenerate. Upon increasing the intensity
of a red detuned drive on these modes, we observe a sharp and synchronized
switching from low occupation quantum states to high occupation classical
fields, accompanied by a pronounced jump from low to high output intensity.Comment: 13 pages, 5 figure
Many Body Physics with Coupled Transmission Line Resonators
We present the Josephson junction intersected superconducting transmission
line resonator. In contrast to the Josephson parametric amplifier, Josephson
bifurcation amplifier and Josephson parametric converter we consider the regime
of few microwave photons. We review the derivation of eigenmode frequencies and
zero point fluctuations of the nonlinear transmission line resonator and the
derivation of the eigenmode Kerr nonlinearities. Remarkably these
nonlinearities can reach values comparable to Transmon qubits rendering the
device ideal for accessing the strongly correlated regime. This is particularly
interesting for investigation of quantum many-body dynamics of interacting
particles under the influence of drive and dissipation. We provide current
profiles for the device modes and investigate the coupling between resonators
in a network of nonlinear transmission line resonators.Comment: submitted to the proceedings of the CEWQO 2012 conferenc
Master equation approach for interacting slow- and stationary-light polaritons
A master equation approach for the description of dark-state polaritons in
coherently driven atomic media is presented. This technique provides a
description of light-matter interactions under conditions of
electromagnetically induced transparency (EIT) that is well suited for the
treatment of polariton losses. The master equation approach allows us to
describe general polariton-polariton interactions that may be conservative,
dissipative or a mixture of both. In particular, it enables us to study
dissipation-induced correlations as a means for the creation of strongly
correlated polariton systems. Our technique reveals a loss mechanism for
stationary-light polaritons that has not been discussed so far. We find that
polariton losses in level configurations with non-degenerate ground states can
be a multiple of those in level schemes with degenerate ground states
Typical solution time for a vertex-covering algorithm on finite-connectivity random graphs
In this letter, we analytically describe the typical solution time needed by
a backtracking algorithm to solve the vertex-cover problem on
finite-connectivity random graphs. We find two different transitions: The first
one is algorithm-dependent and marks the dynamical transition from linear to
exponential solution times. The second one gives the maximum computational
complexity, and is found exactly at the threshold where the system undergoes an
algorithm-independent phase transition in its solvability. Analytical results
are corroborated by numerical simulations.Comment: 4 pages, 2 figures, to appear in Phys. Rev. Let
Migration of bosonic particles across a Mott insulator to superfluid phase interface
We consider a boundary between a Mott insulator and a superfluid region of a
Bose-Hubbard model at unit filling. Initially both regions are decoupled and
cooled to their respective ground states. We show that, after switching on a
small tunneling rate between both regions, all particles of the Mott region
migrate to the superfluid area. This migration takes place whenever the
difference between the chemical potentials of both regions is less than the
maximal energy of any eigenmode of the superfluid. We verify our results
numerically with DMRG simulations and explain them analytically with a master
equation approximation, finding good agreement between both approaches. Finally
we carry out a feasibility study for the observation of the effect in coupled
arrays of micro-cavities and optical lattices.Comment: 5 pages, 6 figures, to appear in Phys. Rev. Let
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