1,954 research outputs found
Spin state readout by quantum jump technique: for the purpose of quantum computing
Utilizing the Pauli-blocking mechanism we show that shining circular
polarized light on a singly-charged quantum dot induces spin dependent
fluorescence. Employing the quantum-jump technique we demonstrate that this
resonance luminescence, due to a spin dependent optical excitation, serves as
an excellent readout mechanism for measuring the spin state of a single
electron confined to a quantum dot.Comment: 11 pages, 4 eps figure
Tensor networks for Lattice Gauge Theories and Atomic Quantum Simulation
We show that gauge invariant quantum link models, Abelian and non-Abelian,
can be exactly described in terms of tensor networks states. Quantum link
models represent an ideal bridge between high-energy to cold atom physics, as
they can be used in cold-atoms in optical lattices to study lattice gauge
theories. In this framework, we characterize the phase diagram of a (1+1)-d
quantum link version of the Schwinger model in an external classical background
electric field: the quantum phase transition from a charge and parity ordered
phase with non-zero electric flux to a disordered one with a net zero electric
flux configuration is described by the Ising universality class.Comment: 9 pages, 9 figures. Published versio
Real-time Dynamics in U(1) Lattice Gauge Theories with Tensor Networks
Tensor network algorithms provide a suitable route for tackling real-time
dependent problems in lattice gauge theories, enabling the investigation of
out-of-equilibrium dynamics. We analyze a U(1) lattice gauge theory in (1+1)
dimensions in the presence of dynamical matter for different mass and electric
field couplings, a theory akin to quantum-electrodynamics in one-dimension,
which displays string-breaking: the confining string between charges can
spontaneously break during quench experiments, giving rise to charge-anticharge
pairs according to the Schwinger mechanism. We study the real-time spreading of
excitations in the system by means of electric field and particle fluctuations:
we determine a dynamical state diagram for string breaking and quantitatively
evaluate the time-scales for mass production. We also show that the time
evolution of the quantum correlations can be detected via bipartite von Neumann
entropies, thus demonstrating that the Schwinger mechanism is tightly linked to
entanglement spreading. To present the variety of possible applications of this
simulation platform, we show how one could follow the real-time scattering
processes between mesons and the creation of entanglement during scattering
processes. Finally, we test the quality of quantum simulations of these
dynamics, quantifying the role of possible imperfections in cold atoms, trapped
ions, and superconducting circuit systems. Our results demonstrate how
entanglement properties can be used to deepen our understanding of basic
phenomena in the real-time dynamics of gauge theories such as string breaking
and collisions.Comment: 15 pages, 25 figures. Published versio
Trimer liquids and crystals of polar molecules in coupled wires
We investigate the pairing and crystalline instabilities of bosonic and
fermionic polar molecules confined to a ladder geometry. By means of analytical
and quasi-exact numerical techniques, we show that gases of composite molecular
dimers as well as trimers can be stabilized as a function of the density
difference between the wires. A shallow optical lattice can pin both liquids,
realizing crystals of composite bosons or fermions. We show that these exotic
quantum phases should be realizable under current experimental conditions in
finite-size confining potentials.Comment: 5 pages, 3 figures plus additional material; Accepted for publication
in Phys. Rev. Let
Probing topology by "heating": Quantized circular dichroism in ultracold atoms
We reveal an intriguing manifestation of topology, which appears in the
depletion rate of topological states of matter in response to an external
drive. This phenomenon is presented by analyzing the response of a generic 2D
Chern insulator subjected to a circular time-periodic perturbation: due to the
system's chiral nature, the depletion rate is shown to depend on the
orientation of the circular shake. Most importantly, taking the difference
between the rates obtained from two opposite orientations of the drive, and
integrating over a proper drive-frequency range, provides a direct measure of
the topological Chern number of the populated band (): this "differential
integrated rate" is directly related to the strength of the driving field
through the quantized coefficient . Contrary to the
integer quantum Hall effect, this quantized response is found to be non-linear
with respect to the strength of the driving field and it explicitly involves
inter-band transitions. We investigate the possibility of probing this
phenomenon in ultracold gases and highlight the crucial role played by edge
states in this effect. We extend our results to 3D lattices, establishing a
link between depletion rates and the non-linear photogalvanic effect predicted
for Weyl semimetals. The quantized circular dichroism revealed in this work
designates depletion-rate measurements as a universal probe for topological
order in quantum matter.Comment: 10 pages, 5 figures (including Sup. Mat.). Revised version, accepted
for publicatio
Long Distance Coupling of a Quantum Mechanical Oscillator to the Internal States of an Atomic Ensemble
We propose and investigate a hybrid optomechanical system consisting of a
micro-mechanical oscillator coupled to the internal states of a distant
ensemble of atoms. The interaction between the systems is mediated by a light
field which allows to couple the two systems in a modular way over long
distances. Coupling to internal degrees of freedom of atoms opens up the
possibility to employ high-frequency mechanical resonators in the MHz to GHz
regime, such as optomechanical crystal structures, and to benefit from the rich
toolbox of quantum control over internal atomic states. Previous schemes
involving atomic motional states are rather limited in both of these aspects.
We derive a full quantum model for the effective coupling including the main
sources of decoherence. As an application we show that sympathetic ground-state
cooling and strong coupling between the two systems is possible.Comment: 14 pages, 5 figure
Strongly correlated gases of Rydberg-dressed atoms: quantum and classical dynamics
We discuss techniques to generate long-range interactions in a gas of
groundstate alkali atoms, by weakly admixing excited Rydberg states with laser
light. This provides a tool to engineer strongly correlated phases with reduced
decoherence from inelastic collisions and spontaneous emission. As an
illustration, we discuss the quantum phases of dressed atoms with dipole-dipole
interactions confined in a harmonic potential, as relevant to experiments. We
show that residual spontaneous emission from the Rydberg state acts as a
heating mechanism, leading to a quantum-classical crossover.Comment: 4 pages, 4 figure
Forages for Horses Workshop Meets the Needs of a Growing Clientele
A growing number of people are purchasing horses for pleasure riding but have very limited knowledge about basic forage production practices. The Ohio State University Extension Forages for Horses workshop was developed by agents and specialists to teach horse owners and stable managers basic forage management concepts. Topics taught in this 2-evening workshop included: anatomy and physiology; plant growth; soil fertility; species selection; pasture renovation; hay storage; and poisonous plant identification. Evaluation of the program was positive, and participants indicated they gained new knowledge as evidenced by pre and post-test scores
Mesoscopic Rydberg Gate based on Electromagnetically Induced Transparency
We demonstrate theoretically a parallelized C-NOT gate which allows to
entangle a mesoscopic ensemble of atoms with a single control atom in a single
step, with high fidelity and on a microsecond timescale. Our scheme relies on
the strong and long-ranged interaction between Rydberg atoms triggering
Electromagnetically Induced Transparency (EIT). By this we can robustly
implement a conditional transfer of all ensemble atoms among two logical
states, depending on the state of the control atom. We outline a many body
interferometer which allows a comparison of two many-body quantum states by
performing a measurement of the control atom.Comment: published versio
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