Entanglement of Quantum States  

In General > s.a. correlations; quantum experiments and foundations; uncertainty.
* Idea: A linking that persists between the wave functions of particles (photons, ions) even when isolated from one another; Two subsystems are entangled if the total wave function is not factorizable, and values cannot be assigned to observables for the individual systems; 2007, a notion of generalized entanglement has emerged, defined through expectation values of preferred observables, without reference to a subsystem decomposition.
* History: 2000, Long the subject of discussion by philosophers of quantum theory, has recently come to play an essential role for physicists in their development of quantum information theory; Entangled state of 4 particles, and between Be atoms achieved; 2001, Entangled state of two trillion-atom gas clouds achieved; 2003, Two solid-state superconducting qubits entangled over 0.7 mm (earlier only micron scale); 2003, Effects seen in the bulk properties of a magnetic salt crystal [@ news pw(03)sep]; 2004, 3- and 4-photon entanglement produced, beating the diffraction limit [@ news pw(04)may]; 2005, Entangled states of 6 Be atoms and 8 Ca atoms [@ news pw(05)dec]; 2007, entanglement sudden death observed [@ news pw(07)may].
* And non-locality: It is often assumed that the most non-local states are the maximally entangled ones; This is not the case.
@ II: Kwiat & Hardy AJP(00) [quantum cakes]; Aczel 02; Terhal et al PT(03)apr; Adesso a0706 ["social aspects"].
@ Reviews, intros: Eckert et al qp/02-in; Eisert & Plenio IJQI(03)qp [continuous variables]; 4 · Horodecki qp/07/RMP; Bengtsson & Zyczkowski 06.
@ General references: Corwin AJP(84); Zyczkowski PRA(99) [volume]; Brukner et al qp/01; Kauffman & Lomonaco NJP(02)qp [quantum vs topological]; Terhal qp/03-in ['monogamy']; Viola et al qp/04-in [for sets of observables]; Kirkpatrick qp/04 [interpretation]; Shih a0706 [conceptual].
@ Subsystem-independent: Barnum et al qp/03, Viola & Barnum qp/07-in [based on observables].
@ Related topics: Schlienz & Mahler PRA(95); Lo & Popescu qp/97; Peres PS(98)qp/97; Yu Shi AdP(00)qp/98 [Gedankenexperiments]; D'Ariano et al PLA(00)qp [Bell measurements]; Ghirardi et al JSP(02)qp/01; Verstraete et al PRL(04)qp/03 [vs correlations]; Ghirardi & Marinatto PRA(04)qp [and indistinguishability], O&S(05)qp [identical particles, criteria]; Hewitt-Horsman & Vedral PRA(07)qp/06 [in Heisenberg picture]; Vedral qp/07/JMO [from higher-dimensional classical correlations]; Naudts & Verhulst PRA(07) [ensemble-averaged].
@ And non-locality: Methot & Scarani QIC(07)qp/06; Barrett et al PRL(06)qp [maximally entangled states]; Koashi et al a0709.

Measures of Entanglement > s.a. entropy in quantum mechanics; phenomenology and examples.
* Idea: The standard entanglement measure for a pure state is sin2, where is the angle between the state and the closest separable one.
@ Reviews: Bruß JMP(02); Myhr qp/04-ms; Plenio & Virmani QIC(07)qp/05.
@ General references: Popescu & Rohrlich PRA(97)qp/96 [entropy]; Schulman & Mozyrsky qp/97; Vedral et al PRL(97)qp; Nielsen PRL(99)qp/98 [partial order]; Virmani & Plenio PLA(00)qp/99; Rudolph JMP(01)mp/00; Blanchard et al JPA(01) [decoherence-based]; Majewski qp/01-in; Zyczkowski & Bengtsson AP(02)qp/01; Eisert et al JPA(02)qp/01 [infinite-dimensional systems]; Vidal & Werner PRA(02) [computable]; Nagel & Raggio qp/03; Partovi PRL(04)qp/03; Yukalov PRL(03)qp [as operator action]; Christandl & Winter JMP(04); Cavalcanti et al PRA(05)qp [maximal entanglement and purity]; Mintert et al PRP(05)qp [and dynamics]; Pawlowski & Czachor PRA(06)qp/05 [ambiguity, photon]; Datta et al PRA(07)qp/06 [bounds]; Mintert & Buchleitner PRL(07) [for mixed states]; Ostapchuk et al a0707 [interpretation]; Gour & Roy a0711; Blasone et al PRA-a0712 [geometric].
@ Experimental: Gühne et al PRL(07)qp/06 [estimate]; Kothe & Björk PRA(07)qp/06 [through local observable correlations]; Badziag et al PRL(08) [experimentally friendly sufficient conditions]; Zhang et al a0806 [for mixed states].
@ Uniqueness: Rudolph JMP(01)qp; Donald et al JMP(02)qp/01.
@ Multipartite: Eisert & Briegel PRA(01)qp/00; Meyer & Wallach qp/01; Miyake PRA(03); Heydari & Björk JPA(04)qp/04; Pitowsky qp/06-wd [entanglement classes]; Adesso et al qp/06; Facchi et al IJQI(07)qp/06; Cardy a0708-in [and von Neumann entropy]; Facchi et al a0803 [statistical mechanics]; Teresi a0805.

Other References > s.a. geometric phase; hidden variables; phase transition; wigner functions.
@ And information theory: Cerf & Adami PhyD(98)qp/96 [and measurement]; Plenio & Vedral CP(98)qp [rev]; Macchiavello PhyA(04); Eisert qp/06-PhD; Ainsworth FP(07).
@ Dynamics: Zyczkowski et al PRA(02)qp/00; Zanardi PRA(01) [entanglement of evolution]; Giovannetti et al EPL(03)qp/02; Doronin PRA(03)qp; Suarez qp/03 [no time flow]; Durt qp/04 [and interactions]; Ghose & Sanders PRA(04)qp [chaotic systems]; Viguie et al NJP(05)qp [work extraction]; Batle et al PRA(05)qp [and speed of evolution]; Dahlsten et al JPA(07)qp [emergence in 2-party random process].
@ Production: Franson a0704 [superluminal]; Abrey & Vallejos PRA(07) [bounds]; Ficek & Tanas a0802 [delayed].
@ Loss, disentanglement: Mor qp/98; Dodd & Halliwell PRA(04)qp/03, Carvalho et al PRL(04) [and decoherence]; Dodd PRA(04)qp/03 [dissipative open systems]; Rey et al cm/07 [noise-resistant entanglement]; Buscemi a0802-in [irreversibility]; Maniscalco et al PRL(08) [protection, using Zeno effect].
@ Sudden death: Almeida et al Sci(07)apr + pw(07)may; O Terra Cunha JNP(07); Al-Qasimi & James a0707; Ann & Jaeger a0707-PLA.
@ Limits to entanglement: Gambini et al a0708 [from use of realistic rods].
@ Multiscale entanglement renormalization ansatz: Cincio et al PRL(08) [2D Ising model].
@ Geometry: Kus & Zyczkowski PRA(01); Bertlmann et al PRA(02)qp/01; Lévay JPA(04)qp/03; Leinaas et al PRA(06)qp; Zyczkowski & Bengtsson in(06)qp [intro]; Sugita a0704-in [and topological links]; Basu & Bandyopadhyay IJGMP(07) [and geometric phase]; Cavalcanti et al a0709 [and geometry of set of quantum states].
@ Thermodynamics: Horodecki et al PRL(02); Vedral a0706 [dissipative systems]; > s.a. quantum statistical mechanics.
@ Classical analog: Spreeuw FP(98); Massar et al PRA(01)qp/00; Lakshminarayan qp/01; Collins & Popescu PRA(02)qp/01.
@ Conceptual: Esfeld SHPMP(04) [and metaphysics of relations].


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