1,905 research outputs found
Quantum Many-Body Phenomena in Coupled Cavity Arrays
The increasing level of experimental control over atomic and optical systems
gained in the past years have paved the way for the exploration of new physical
regimes in quantum optics and atomic physics, characterised by the appearance
of quantum many-body phenomena, originally encountered only in condensed-matter
physics, and the possibility of experimentally accessing them in a more
controlled manner. In this review article we survey recent theoretical studies
concerning the use of cavity quantum electrodynamics to create quantum
many-body systems. Based on recent experimental progress in the fabrication of
arrays of interacting micro-cavities and on their coupling to atomic-like
structures in several different physical architectures, we review proposals on
the realisation of paradigmatic many-body models in such systems, such as the
Bose-Hubbard and the anisotropic Heisenberg models. Such arrays of coupled
cavities offer interesting properties as simulators of quantum many-body
physics, including the full addressability of individual sites and the
accessibility of inhomogeneous models.Comment: overview article, 27 pages, 31 figure
Quantum Many-Body Phenomena in Coupled Cavity Arrays
The increasing level of experimental control over atomic and optical systems gained in the past years have paved the way for the exploration of new physical regimes in quantum optics and atomic physics, characterised by the appearance of quantum many-body phenomena, originally encountered only in condensed-matter physics, and the possibility of experimentally accessing them in a more controlled manner. In this review article we survey recent theoretical studies concerning the use of cavity quantum electrodynamics to create quantum many-body systems. Based on recent experimental progress in the fabrication of arrays of interacting micro-cavities and on their coupling to atomic-like structures in several different physical architectures, we review proposals on the realisation of paradigmatic many-body models in such systems, such as the Bose-Hubbard and the anisotropic Heisenberg models. Such arrays of coupled cavities offer interesting properties as simulators of quantum many-body physics, including the full addressability of individual sites and the accessibility of inhomogeneous models
An experimental approach for investigating many-body phenomena in Rydberg-interacting quantum systems
Recent developments in the study of ultracold Rydberg gases demand an
advanced level of experimental sophistication, in which high atomic and optical
densities must be combined with excellent control of external fields and
sensitive Rydberg atom detection. We describe a tailored experimental system
used to produce and study Rydberg-interacting atoms excited from dense
ultracold atomic gases. The experiment has been optimized for fast duty cycles
using a high flux cold atom source and a three beam optical dipole trap. The
latter enables tuning of the atomic density and temperature over several orders
of magnitude, all the way to the Bose-Einstein condensation transition. An
electrode structure surrounding the atoms allows for precise control over
electric fields and single-particle sensitive field ionization detection of
Rydberg atoms. We review two experiments which highlight the influence of
strong Rydberg--Rydberg interactions on different many-body systems. First, the
Rydberg blockade effect is used to pre-structure an atomic gas prior to its
spontaneous evolution into an ultracold plasma. Second, hybrid states of
photons and atoms called dark-state polaritons are studied. By looking at the
statistical distribution of Rydberg excited atoms we reveal correlations
between dark-state polaritons. These experiments will ultimately provide a
deeper understanding of many-body phenomena in strongly-interacting regimes,
including the study of strongly-coupled plasmas and interfaces between atoms
and light at the quantum level.Comment: 14 pages, 11 figures; submitted to a special issue of 'Frontiers of
Physics' dedicated to 'Quantum Foundation and Technology: Frontiers and
Future
QUANTUM MANY-BODY PHENOMENA IN ULTRA-COLD ATOMS IN OPTICAL LATTICES
Two models are discussed here to illustrate the quantum many-body phenomena in mixtures of ultra-cold atoms in optical lattices. The first model describes a mixture of two species of bosonic atoms of equal masses in optical lattices and the second describes a mixture of heavy bosonic atoms and light fermionic atoms in optical lattices. For both models, we assume the trap is present and use parameters typical in experiment.
For the first model, the discussion is aimed at providing a thorough description of the collective behavior of the binary mixture in various interaction regions, with emphasis on two many-body phenomena, pairing and anti-pairing, as a result of the inter-species interaction. The pairing leads to a new type of superfluid order, called the paired superfluid (PSF) and the anti-pairing leads to another type of superfluid order, called the counter-flow superfluid (CFSF). In addition, we discuss the coexistence of charge density wave order with the three superfluid orders in the strong interaction region. We use both Luttinger liquid theory and the time evolving block decimation (TEBD) method to study this model in one dimension. The discussion is organized in three parts: the phase diagram and the correlation functions; the noise correlation functions; and the transport properties. Two phase diagrams are constructed to map the different orders in the parameter space. The correlation functions, include noise correlations, are carefully examined for the determination of the orders and for possible detection methods. In the end, the transport properties of the PSF and CFSF orders are studied through the dipole oscillation induced by trap displacement.
For the second model, examining a mixture of heavy bosons and light fermions, the discussion is oriented toward determining the thermal properties of the mixture for attractive inter-species interactions. This work is motivated by experiments creating artificial molecules through optical and magnetic control of ultra-cold atoms. We use the strong coupling (SC) expansion method to evaluate the density profile, the onsite inter-species correlations, the density fluctuations and the entropy per particle. Analytical expressions are derived for all the quantities above as well as the partition function. To benchmark the accuracy, the SC calculations are compared with inhomogeneous dynamical mean field theory (IDMFT) and Monte Carlo (MC) simulation. From the calculations, we find that 1) the efficiency of creating pre-formed molecules is significantly increased by confining the mixtures onto optical lattices; 2) the temperature of the mixtures in optical lattices can be reliably estimated through the density gradient and the density fluctuations
Bose-Einstein Condensation and strong-correlation behavior of phonons in ion traps
We show that the dynamics of phonons in a set of trapped ions interacting
with lasers is described by a Bose-Hubbard model whose parameters can be
externally adjusted. We investigate the possibility of observing several
quantum many-body phenomena, including (quasi) Bose-Einstein condensation as
well as a superfluid-Mott insulator quantum phase transition.Comment: 5 pages, 3 figure
Probing spatial spin correlations of ultracold gases by quantum noise spectroscopy
Spin noise spectroscopy with a single laser beam is demonstrated
theoretically to provide a direct probe of the spatial correlations of cold
fermionic gases. We show how the generic many-body phenomena of anti-bunching,
pairing, antiferromagnetic, and algebraic spin liquid correlations can be
revealed by measuring the spin noise as a function of laser width, temperature,
and frequency.Comment: Revised version. 4 pages, 3 figures. Accepted for PR
A Quantum Dot in the Kondo Regime Coupled to Superconductors
The Kondo effect and superconductivity are both prime examples of many-body
phenomena. Here we report transport measurements on a carbon nanotube quantum
dot coupled to superconducting leads that show a delicate interplay between
both effects. We demonstrate that the superconductivity of the leads does not
destroy the Kondo correlations on the quantum dot when the Kondo temperature,
which varies for different single-electron states, exceeds the superconducting
gap energy
Many-Body Physics with Ultracold Gases
This article reviews recent experimental and theoretical progress on
many-body phenomena in dilute, ultracold gases. Its focus are effects beyond
standard weak-coupling descriptions, like the Mott-Hubbard-transition in
optical lattices, strongly interacting gases in one and two dimensions or
lowest Landau level physics in quasi two-dimensional gases in fast rotation.
Strong correlations in fermionic gases are discussed in optical lattices or
near Feshbach resonances in the BCS-BEC crossover.Comment: revised version, accepted for publication in Rev. Mod. Phy
Photon-Photon Interactions via Rydberg Blockade
We develop the theory of light propagation under the conditions of electromagnetically induced transparency in systems involving strongly interacting Rydberg states. Taking into account the quantum nature and the spatial propagation of light, we analyze interactions involving few-photon pulses. We show that this system can be used for the generation of nonclassical states of light including trains of single photons with an avoided volume between them, for implementing photon-photon gates, as well as for studying many-body phenomena with strongly correlated photons
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