998 research outputs found
Classical and quantum complementarity
Two complementary observables can be measured simultaneously so that the
exact individual distributions can be recovered by a proper data inversion. We
apply this program to the paradigmatic example of the Young interferometer from
the classical and quantum points of view. We show complete parallelism between
complementarity in the quantum and classical theories. In both domains,
complementarity manifests in a pathological behavior for the inferred joint
distribution.Comment: 6 pages, 2 figure
CaracterizaciĂłn de haces Ăłpticos vĂa tomografĂa en el espacio de fases
Tesis inĂ©dita de la Universidad Complutense de Madrid, Facultad de Ciencias FĂsicas, Departamento de Ăptica, leĂda el 12-09-2014Depto. de ĂpticaFac. de Ciencias FĂsicasTRUEunpu
Quantum metrology with nonclassical states of atomic ensembles
Quantum technologies exploit entanglement to revolutionize computing,
measurements, and communications. This has stimulated the research in different
areas of physics to engineer and manipulate fragile many-particle entangled
states. Progress has been particularly rapid for atoms. Thanks to the large and
tunable nonlinearities and the well developed techniques for trapping,
controlling and counting, many groundbreaking experiments have demonstrated the
generation of entangled states of trapped ions, cold and ultracold gases of
neutral atoms. Moreover, atoms can couple strongly to external forces and light
fields, which makes them ideal for ultra-precise sensing and time keeping. All
these factors call for generating non-classical atomic states designed for
phase estimation in atomic clocks and atom interferometers, exploiting
many-body entanglement to increase the sensitivity of precision measurements.
The goal of this article is to review and illustrate the theory and the
experiments with atomic ensembles that have demonstrated many-particle
entanglement and quantum-enhanced metrology.Comment: 76 pages, 40 figures, 1 table, 603 references. Some figures bitmapped
at 300 dpi to reduce file siz
Entanglement and Complete Positivity: Relevance and Manifestations in Classical Scalar Wave Optics
Entanglement of states and Complete Positivity of maps are concepts that have
achieved physical importance with the recent growth of quantum information
science. They are however mathematically relevant whenever tensor products of
complex linear (Hilbert) spaces are involved. We present such situations in
classical scalar paraxial wave optics where these concepts play a role:
propagation characteristics of coherent and partially coherent Gaussian beams;
and the definition and separability of the family of Twisted Gaussian Schell
Model (TGSM) beams. In the former, the evolution of the width of a projected
one-dimensional beam is shown to be a signature of entanglement in a
two-dimensional amplitude. In the latter, the partial transpose operation is
seen to explain key properties of TGSM beams.Comment: 7 pages Revtex 4-
Multiphoton Quantum Optics and Quantum State Engineering
We present a review of theoretical and experimental aspects of multiphoton
quantum optics. Multiphoton processes occur and are important for many aspects
of matter-radiation interactions that include the efficient ionization of atoms
and molecules, and, more generally, atomic transition mechanisms;
system-environment couplings and dissipative quantum dynamics; laser physics,
optical parametric processes, and interferometry. A single review cannot
account for all aspects of such an enormously vast subject. Here we choose to
concentrate our attention on parametric processes in nonlinear media, with
special emphasis on the engineering of nonclassical states of photons and
atoms. We present a detailed analysis of the methods and techniques for the
production of genuinely quantum multiphoton processes in nonlinear media, and
the corresponding models of multiphoton effective interactions. We review
existing proposals for the classification, engineering, and manipulation of
nonclassical states, including Fock states, macroscopic superposition states,
and multiphoton generalized coherent states. We introduce and discuss the
structure of canonical multiphoton quantum optics and the associated one- and
two-mode canonical multiphoton squeezed states. This framework provides a
consistent multiphoton generalization of two-photon quantum optics and a
consistent Hamiltonian description of multiphoton processes associated to
higher-order nonlinearities. Finally, we discuss very recent advances that by
combining linear and nonlinear optical devices allow to realize multiphoton
entangled states of the electromnagnetic field, that are relevant for
applications to efficient quantum computation, quantum teleportation, and
related problems in quantum communication and information.Comment: 198 pages, 36 eps figure
MuSR method and tomographic probability representation of spin states
Muon spin rotation/relaxation/resonance (MuSR) technique for studying matter
structures is considered by means of a recently introduced probability
representation of quantum spin states. A relation between experimental MuSR
histograms and muon spin tomograms is established. Time evolution of muonium,
anomalous muonium, and a muonium-like system is studied in the tomographic
representation. Entanglement phenomenon of a bipartite muon-electron system is
investigated via tomographic analogues of Bell number and positive partial
transpose (PPT) criterion. Reconstruction of the muon-electron spin state as
well as the total spin tomography of composed system is discussed.Comment: 20 pages, 4 figures, LaTeX, submitted to Journal of Russian Laser
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