Macroscopic Quantum Systems  

In General > s.a. classical limit [including correspondence principle, localization]; classical-quantum relationship; many-particle quantum systems.
* Idea: A macroscopic quantum state emerges in a sample of matter when the particles' thermal wavelength approaches the interparticle spacing; The particles then lose their individual identities and merge into a single correlated quantum state of matter, whose behavior differs markedly from that of a collection of distinguishable pointlike particles.
* Examples: Superfluid helium, superconductors, gaseous Bose-Einstein condensates, and the interiors of neutron stars.
@ General references: Bose et al PRA(99); Gomatam JCS(99)-a0708; Carati & Galgani FP(01); Sewell 02; Björk & Mana JOB(04)qp/03 [criterion]; Biswas qp/03; Pitowsky PRA(04); Helland qp/05; Khrennikov a0705 [quantumlike description]; Schützhold PoS-a0712 [back-reaction]; Zeh EPJH(11)-a0804 [Feynman, and gravitational fields]; Chou et al JPCS(11)-a1106 [framework, large-N expansion]; Brezinski & Rupnick a1312; Sekatski et al PRL(14)-a1402 [quantumness]; Fröwis et al RMP(18)-a1706 [rev]; > s.a. experiments; logic.
@ Condensed-matter type: Bene qp/97/PRL; Balucani et al PRP(03) [correlations]; Grandy FP(04), FP(04), FP(04) [time evolution]; Khrennikov FP(05)qp/04 [concept]; Pitowsky PRA(04) ["combinatorial"]; Bruus & Flensberg 04; Lipparini 08 [fluid]; Caldeira 14 [magnetism, superconductivity, dissipation]; Quandt-Wiese a1701 [solids in quantum superpositions]; news pw(18)jun [nanocrystals]; >  s.a. condensed-matter physics.
@ Examples: O'Connell Nat(10)apr + news ns(10)mar [mechanical resonator]; Jääskeläinen PRA(12) [spherical mass, gravitational self-localization]; Chen JPB(13)-a1302 [optomechanics, theory and experimental concepts]; Hu et al PRA(17)-a1606 [violation of classical physics in a mesoscopic system]; Stamper-Kurn et al Nat(16)sep-a1607, reply Kovachy et al a1607 [macroscopic quantum superpositions still experimentally unestablished].
@ Quantum behavior: news nat(07)nov; Banks a0907 [locality and deviations from classical behavior]; Poot & van der Zant PRP(12)-a1106; Yadin & Vedral PRA(15)-a1407 [new quantumness criterion]; Kryukov JMP(17)-a1710 [evolution]; Dalton a1808 [Bell non-locality].
@ Other foundations / interpretations: Finkelstein qp/98 [many-worlds and pilot-wave]; Lanz et al JPA(07)qp; > s.a. quantum foundations.
@ And measurement: Leggett PTPS(80); Prosperi IJTP(94); Jeong et al JOSA(14)-a1404 [detecting macroscopic quantumness]; news cosmos(18)may [quantum drum from silicon nitride membrane and light]; > s.a. Leggett-Garg Inequality.
@ Related topics: Van Zandt AJP(77)jan [and interference]; Banks a0809 [and locality]; Galvan a0910 [permanent spatial decomposition]; Fröwis & Dür NJP(12)-a1205 [measure of macroscopicity for quantum states]; Altaisky NAP-a1607 [two partial orders, and consciousness].
> Related topics: see classical mechanics [non-quantum systems]; decoherence; Ehrenfest Time; electricity [thermoelectric devices]; Emergent Systems; origin of quantum mechanics; quantum chaos; quantum mechanics formalism [ambiguities]; quantum statistical mechanics [relationship with classical]; Superfluids.

Systems at the Classical-Quantum Boundary > s.a. types of states [semiclassical].
@ General references: Aerts & Durt FP(94) [intermediate systems]; Baseia et al PLA(98) [obtaining non-classical states]; Frasca JPCS(07)qp/06 [and thermodynamic limit]; Doubochinski & Tennenbaum a0711-conf [amplitude quantization, or Macroscopic Quantum Effect, as bridge]; Margolus a0805; Aristov & Nikulov a1006-proc [nanostructures]; Kofler & Brukner a1009 [limits to applicability of quantum mechanics]; Chafin a1308 [wave functions for classical bodies]; Jeong et al OC(15)-a1407 [quantumness]; Zinner EPJwc(16)-a1510 [1D cold atoms, few- to many-body crossover].
@ Specific systems: Alicki PRA(02)qp/01 [fullerenes]; Tebbenjohanns et al PRL(19) [optically levitated nanosphere].
@ Emergence of macroscopic realism: Portolan et al PRA(06) [for photons]; Kofler & Brukner PRL(07)qp/06; Kofler & Brukner PRL(08)-a0706 [conditions for quantum violation of macroscopic realism]; Nimmrichter & Hornberger PRL(13) + news ns(13)apr, pw(13)apr [degree of macroscopicity]; Colin et al PRA(16)-a1403 [spread in position of a freely falling nanosphere]; Clemente & Kofler PRA(15)-a1501 [conditions for macroscopic realism]; Romero-Rochin a1504.
@ Dequantization: Isidro JPA(02)ht/01; Abrikosov et al AP(05)qp/04 [geometric].
> Related topics: see Correspondence Principle; fluctuations; Superpositions [meso- and macroscopic].

Coupled / Hybrid Classical and Quantum Systems > s.a. states in quantum field theory [hybrid field systems].
* Issue: Is a system with coupled classical and quantum degrees of freedom consistent? It can be, provided it is stochastic.
* Rem: Hybrid systems are sometimes used as a tool to simplify the analysis of many-body systems, as in mean-field theory.
@ General references: Blanchard & Jadczyk PLA(93) [model]; Anderson qp/95-proc [backreaction of quantum variables on quasiclassical ones]; Salcedo PRA(96); Halliwell PRD(98)qp/97 [from decoherent histories]; Prezhdo & Kisil PRA(97)qp/96; Antoniou et al MPLA(99) [Hamiltonian]; Caro & Salcedo PRA(99) [impediments]; Dias JPA(01)qp/99 ["half quantization"]; Diósi qp/99-in; Peres & Terno PRA(01)qp/00; Prezhdo & Brooksby PRL(01), comment Salcedo PRL(03)qp [quantum backreaction and the Bohmian interpretation]; Kowalski et al PLA(02); Sahoo JPA(04)qp/03 [observable algebras]; Kisil EPL(05)qp [2 copies of Heisenberg group]; Hall & Reginatto PRA(05)qp [classical and quantum ensembles]; Grigorescu CJP(07)qp/06 [quantum particle + classical environment, variational principle]; Zhang & Wu PRL(06) [Lorentz-like geometric force]; Zhan et al JChemP(08)-a0803 [approaches]; Hall PRA(08)-a0804 [consistent formulation]; Reginatto & Hall JPCS(09)-a0905; Gerasimenko JChemP(09)-a0909; Elze et al JPCS(11)-a1103 [path-integral formulation], PRD(12)-a1111; Salcedo PRA(12)-a1201 [consistency requirement]; Elze JPCS(12)-a1202 [four questions]; Barceló et al PRA(12)-a1206; Elze JPCS(13)-a1306 [summary]; Gil & Salcedo PRA(17)-a1612 [canonical structure]; Gay-Balmaz & Tronci a1802 [from Koopman-von Neumann theory]; Bhole et al JPComm(20)-a1812 [witnesses of non-classicality]; Amin & Walton a2009 [hybrid quantum-classical bracket]; Tronci & Gay-Balmaz LNCS-a2104, LNCS-a2104 [from Koopman-van Hove theory].
@ Inconsistency: Terno FP(06)qp/04, reply Sudarshan qp/04; Ahmadzadegan et al PRA(16)-a1510 [robustness of classicality]; Ares et al a1801; Braak & Mannhart a1811 [inconsistency between quantum theory and thermodynamics].
@ Examples: Semenov et al JPB(06)qp/05 [oscillator + thermal bath]; Metaxas PRD(07)ht/06 [two scalar fields, path-integral approach]; Aguilar & Berglund JMP(08)-a0805 [two-level system + classical noise]; Mousavi & Golshani PS(08) [2-level atom + classical field]; Poma & Delle Site PRL(10) [molecular models, path-integral description]; Chua et al PRA(11)-a1109 [harmonically coupled particles]; Treutlein et al a1210-ch; Restrepo et al PRL(14) [optomechanical resonator with a quantum dot inside]; Sergi TCA(15)-a1502 [systems with light and heavy degrees of freedom, non-Hermitian]; Koide a1602 [simplified model of QED]; Rubin a1610 [density matrix embedding theory as a tool]; news pw(17)sep [measuring quantized mechanical oscillations]; Reginatto & Hall a1809 [quantum fields and classical gravity]; Oppenheim et al a2011 [toy models]; > s.a. Mean-Field Theory.
@ Ground state and coherent state: McDermott & Redmount qp/04 [2 oscillators].
@ Intervention, measurement: Diósi & Halliwell PRL(98)qp/97; Peres PRA(00), PRA(00); > s.a. types of measurements [continuous].

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