I am going to post here all newly submitted articles on the arXiv related to superconducting circuits. If your article has been accidentally forgotten, feel free to contact me
13
Nov
2011
Entanglement dynamics of a superconducting phase qubit coupled to a two-level system
We report the observation and quantitative characterization of driven and
spontaneous oscillations of quantum entanglement, as measured by concurrence,
in a bipartite system consisting
of a macroscopic Josephson phase qubit coupled
to a microscopic two-level system. The data clearly show the behavior of
entanglement dynamics such as sudden death and revival, and the effect of
decoherence and ac driving on entanglement.
08
Jun
2011
Quantum simulator of an open quantum system using superconducting qubits: exciton transport in photosynthetic complexes
Open quantum system approaches are widely used in the description of
physical, chemical and biological systems. A famous example is electronic
excitation transfer in the initial stage
of photosynthesis, where harvested
energy is transferred with remarkably high efficiency to a reaction center.
This transport is affected by the motion of a structured vibrational
environment, which makes simulations on a classical computer very demanding.
Here we propose an analog quantum simulator of complex open system dynamics
with a precisely engineered quantum environment. Our setup is based on
superconducting circuits, a well established technology. As an example, we
demonstrate that it is feasible to simulate exciton transport in the
Fenna-Matthews-Olson photosynthetic complex. Our approach allows for a
controllable single-molecule simulation and the investigation of energy
transfer pathways as well as non-Markovian noise-correlation effects.
14
Mä
2011
Dynamical Autler-Townes control of a phase qubit
Routers, switches, and repeaters are essential components of modern
information-processing systems. Similar devices will be needed in future
superconducting quantum computers. In this
work we investigate experimentally
the time evolution of Autler-Townes splitting in a superconducting phase qubit
under the application of a control tone resonantly coupled to the second
transition. A three-level model that includes independently determined
parameters for relaxation and dephasing gives excellent agreement with the
experiment. The results demonstrate that the qubit can be used as a ON/OFF
switch with 100 ns operating time-scale for the reflection/transmission of
photons coming from an applied probe microwave tone. The ON state is realized
when the control tone is sufficiently strong to generate an Autler-Townes
doublet, suppressing the absorption of the probe tone photons and resulting in
a maximum of transmission.
15
Jun
2010
Bose-Hubbard dynamics of polaritons in a chain of circuit QED cavities
We investigate a chain of superconducting stripline resonators, each
interacting with a transmon qubit, that are capacitively coupled in a row. We
show that the dynamics of this system
can be described by a Bose-Hubbard
Hamiltonian with attractive interactions for polaritons, superpositions of
photons and qubit excitations. This setup we envisage constitutes one of the
first platforms where all technological components that are needed to
experimentally study chains of strongly interacting polaritons have already
been realized. By driving the first stripline resonator with a microwave source
and detecting the output field of the last stripline resonator one can
spectroscopically probe properties of the system in the driven dissipative
regime. We calculate the stationary polariton density and density-density
correlations $g^{(2)}$ for the last cavity which can be measured via the output
field. Our results display a transition from a coherent to a quantum field as
the ratio of on site interactions to driving strength is increased.