|  Semiclassical States of Quantum Systems | 
In General
  > s.a. coherent states; mixed states;
  quantum field theory states; quantum locality.
  * Idea: With respect
    to correlations, a bipartite state is called classical if it is left
    undisturbed by a certain local von Neumann measurement.
  * Idea: Semiclassical
    states are states with a classical interpretation, in which the probability
    distributions for a chosen set of observables are narrowly peaked around
    classical values; Common examples are coherent and Gaussian/squeezed states.
  $ Def: A set of semiclassical
    states is a collection {|ω\(\rangle\)} of states labelled by
    points ω in Γ in phase space, together with a set
    {(Fi,
    εi,
    δi)}
    of observables and tolerances, such that
    |\(\langle\)ω|Fi|ω\(\rangle\)
    − Fi(ω )|
    ≤ εi and
    (ΔFi)ω2
    ≤ δi,
    for all ω and i.
  @ General references: Solovej & Spitzer CMP(03) [semiclassical calculus];
    Genoni et al PRA(07)-a0704 [departure from Gaussianity];
    Badziag et al PRL(09) [there are no "classical" states].
  @ Minimum uncertainty: Trifonov et al PRL(01) [discrete-valued observables];
    Detournay et al PRD(02) [with gup];
    de Gosson PLA(04) [optimal];
    Al-Hashimi & Wiese AP(09)-a0907 [relativistic and non-relativistic];
    Kisil ch(15)-a1312
      [minimal-uncertainty states and holomorphy-type conditions on the images of the respective wavelet transform];
    Korzekwa & Lostaglio a1602 [and classical noise];
    > s.a. coherent and Squeezed States.
  @ With classical behavior:
    Davidovic & Lalovic JPA(98);
    Kuś & Bengtsson PRA(09)-a0905 [most-classical states];
    Koide PLA(15)-a1412 [extracting classical degrees of freedom, and hybrid systems];
    > s.a. macroscopic quantum systems.
  @ Gaussian states: Nicacio et al PLA(10) [generalized Gaussian cat states];
    Olivares EPJST(12)-a1111 [Gaussian Wigner functions];
    de Gosson a1204
      [optimal Gaussian states for joint position-momentum measurements];
    Hagedorn a1301
      [minimal-uncertainty product for complex Gaussian wave packets];
    Buono et al a1609 [quantum coherence of Gaussian states];
    de Gosson a1809
      [separability of bipartite Gaussian mixed states]
  @ Non-classical states: Vogel PRL(00) [sho];
    Foldi PhD(03)qp/04 [and decoherence];
    Hammerer et al a1211-ch;
    Szymusiak a1701
      [states that are "most" quantum with respect to a given measurement];
    Adhikary et al a1710 [framework];
    > s.a. degree of classicality; mesoscopic systems.
  @ Related topics:
    Senitzky PRL(81) [statistics];
    Shvedov AP(02)mp/01 [symmetries],
    mp/01 [group actions];
    de Gosson mp/02 [symplectic area];
    Hájíček FP(09)-a0901 [maximum-entropy states];
    Ishikawa & Tobita PTP(09)-a0906 [wave-packet coherent length];
    Budiyono PRA(09)-a0907
      ["most probable wave function", and finite-size progressing solution];
    Luis PRA(11) [classicality and probabilities of non-commuting observables];
    de Gosson a1205;
    Tsobanjan JMP(15)-a1410 [on finite-dimensional Lie algebras].
  > Related topics:
    see complex structure; conservation laws
    [and symmetries]; dirac fields [wave packets]; entanglement;
    wigner functions; Explanation;
    fluctuation; quantum effects.
 Related
  pages: see quantum state evolution; relationship classical-quantum theory;
  semiclassical effects and degree of quantumness; semiclassical limit.
 Related
  pages: see quantum state evolution; relationship classical-quantum theory;
  semiclassical effects and degree of quantumness; semiclassical limit.
Special Types of Systems > s.a. phase transition.
  * Issue: Is environmental decoherence
    required to prevent classically chaotic systems (e.g., tumbling satellites such as
    Hyperion) from exhibiting non-classical behavior within a short time span?
  @ General references:
    Arsenović et al PRA(99) [spin-1/2];
    Blanchard & Olkiewicz PLA(00) [open systems];
    Yang & Kellman PRA(02) [EBK wave function near resonance];
    Schulman PRL(04) [particles, evolution of spreads];
    Giraud et al PRA(08) [spin states];
    Pedram EPL(10)-a1001 [1D];
    > s.a. oscillators; photon;
      semiclassical quantum gravity [including non-classical];
      thermal radiation.
  @ Constrained systems:
    Shvedov ht/01 [first-class],
    mp/05-conf [linear C, quadratic H];
    Dell'Antonio & Tenuta JPA(04)mp/03 [with constraining potential];
    Ashtekar et al PRD(05)gq [kinematical and physical states];
    Gambini & Pullin a1207 [totally constrained, self-adjointness of the Hamiltonian].
  @ Chaotic systems: Eckhardt PRP(88);
    Ballentine PRA(01),
    PRA(02);
    Kaplan NJP(02);
    Gong & Brumer PRA(03);
    Schomerus & Jacquod JPA(05);
    Wiebe & Ballentine PRA(05) [classical Hyperion tumbling and decoherence],
    comment Schlosshauer FP(08)qp/06,
    reply Ballentine FP(08);
    Everitt NJP(09)-a0712 [SQUID ring];
    Paul a0901;
    Goletz et al PRE(09)-a0904 [semiclassical, long-time quantum transport];
    Wisniacki et al PRL(10)-a0911 [quantum perturbations];
    Giller & Janiak a1108 [classically chaotic, Maslov-Fedoriuk approach].
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