35 research outputs found
Continuous matrix product states solution for the mixing/demixing transition in one-dimensional quantum fields
We solve the mixing-demixing transition in repulsive one-dimensional
bose-bose mixtures. This is done numerically by means of the continuous matrix
product states variational ansatz. We show that the effective low-energy
bosonization theory is able to detect the transition whenever the Luttinger
parameters are exactly computed. We further characterize the transition by
calculating the ground-state energy density, the field-field fluctuations and
the density correlations.Comment: 5 pages, 3 figure
Continuous matrix product states for coupled fields: Application to Luttinger Liquids and quantum simulators
A way of constructing continuous matrix product states (cMPS) for coupled
fields is presented here. The cMPS is a variational \emph{ansatz} for the
ground state of quantum field theories in one dimension. Our proposed scheme is
based in the physical interpretation in which the cMPS class can be produced by
means of a dissipative dynamic of a system interacting with a bath. We study
the case of coupled bosonic fields. We test the method with previous DMRG
results in coupled Lieb Liniger models. Besides, we discuss a novel application
for characterizing the Luttinger liquid theory emerging in the low energy
regime of these theories. Finally, we propose a circuit QED architecture as a
quantum simulator for coupled fields.Comment: 10 pages, 5 figure
Continuous-matrix-product-state solution for the mixing-demixing transition in one-dimensional quantum fields
We solve the mixing-demixing transition in repulsive one-dimensional Bose-Bose mixtures. This is done numerically by means of the continuous matrix product states variational ansatz. We show that the effective low-energy bosonization theory is able to detect the transition whenever the Luttinger parameters are exactly computed. We further characterize the transition by calculating the ground-state energy density, the field-field
fluctuations, and the density correlations.We acknowledge support from the Spanish DGICYT under Project No. FIS2011-25167 as well as by the Aragon (Grupo FENOL) and the EU Project PROMISCE.Peer Reviewe
Quantum error correction with dissipatively stabilized squeezed cat qubits
Noise-biased qubits are a promising route toward significantly reducing the
hardware overhead associated with quantum error correction. The squeezed cat
code, a non-local encoding in phase space based on squeezed coherent states, is
an example of a noise-biased (bosonic) qubit with exponential error bias. Here
we propose and analyze the error correction performance of a dissipatively
stabilized squeezed cat qubit. We find that for moderate squeezing the bit-flip
error rate gets significantly reduced in comparison with the ordinary cat qubit
while leaving the phase flip rate unchanged. Additionally, we find that the
squeezing enables faster and higher-fidelity gates.Comment: updated and accepted versio
Stationary discrete solitons in circuit QED
We demonstrate that stationary localized solutions (discrete solitons) exist
in a one dimensional Bose-Hubbard lattices with gain and loss in the
semiclassical regime. Stationary solutions, by defi- nition, are robust and do
not demand for state preparation. Losses, unavoidable in experiments, are not a
drawback, but a necessary ingredient for these modes to exist. The
semiclassical calculations are complemented with their classical limit and
dynamics based on a Gutzwiller Ansatz. We argue that circuit QED architectures
are ideal platforms for realizing the physics developed here. Finally, within
the input-output formalism, we explain how to experimentally access the
different phases, including the solitons, of the chain.Comment: 10 pages including appendix, 7 figure
Continuous matrix product states for quantum fields
Martes Cuantico is an initiative for discussion in Zaragoza on recent advances in Quantum Mechanics.Peer reviewe
Universal Gate Set for Continuous-Variable Quantum Computation with Microwave Circuits
We provide an explicit construction of a universal gate set for
continuous-variable quantum computation with microwave circuits. Such a
universal set has been first proposed in quantum-optical setups, but its
experimental implementation has remained elusive in that domain due to the
difficulties in engineering strong nonlinearities. Here, we show that a
realistic microwave architecture allows to overcome this difficulty. As an
application, we show that this architecture allows to generate a cubic phase
state with an experimentally feasible procedure. This work highlights a
practical advantage of microwave circuits with respect to optical systems for
the purpose of engineering non-Gaussian states, and opens the quest for
continuous-variable algorithms based on a few repetitions of elementary gates
from the continuous-variable universal set.Comment: 6+6 pages, 2 figure
Co-evolutionnary network approach to cultural dynamics controlled by intolerance
Starting from Axelrod's model of cultural dissemination, we introduce a
rewiring probability, enabling agents to cut the links with their unfriendly
neighbors if their cultural similarity is below a tolerance parameter. For low
values of tolerance, rewiring promotes the convergence to a frozen monocultural
state. However, intermediate tolerance values prevent rewiring once the network
is fragmented, resulting in a multicultural society even for values of initial
cultural diversity in which the original Axelrod model reaches globalization
Generating Multimode Entangled Microwaves with a Superconducting Parametric Cavity
In this Letter, we demonstrate the generation of multimode entangled states
of propagating microwaves. The entangled states are generated by parametrically
pumping a multimode superconducting cavity. By combining different pump
frequencies, applied simultaneously to the device, we can produce different
entanglement structures in a programable fashion. The Gaussian output states
are fully characterized by measuring the full covariance matrices of the modes.
The covariance matrices are absolutely calibrated using an in situ microwave
calibration source, a shot noise tunnel junction. Applying a variety of
entanglement measures, we demonstrate both full inseparability and genuine
tripartite entanglement of the states. Our method is easily extensible to more
modes.Comment: 5 pages, 1 figures, 1 tabl