Experimental test of quantum nonlocality in three-photon Greenberger–Horne–Zeilinger entanglement

Pan, Jian-Wei; Bouwmeester, Dirk; Daniell, Matthew; Weinfurter, Harald; Zeilinger, Anton

doi:10.1038/35000514

Cited by 1,099 publications

(698 citation statements)

References 27 publications

(5 reference statements)

Supporting

Mentioning

671

Contrasting

Unclassified

Order By: Relevance

“…3.1), and its Hamiltonian can be decomposed into 36 Note that the values A i = ±m F , which we wish to come out associated with the eigenvalues s i = ±1, are determined from equilibrium statistical mechanics; they are not the eigenvalues ofÂ ≡m, which range from −1 to +1 with spacing 2/N, but thermodynamic expectation values around which small fluctuations of order 1/ √ N occur. For low T they would be close to ±1 37 As S is a spin 1 2 , the onlyĤ S that commutes with the full Hamiltonian has the form −b zŝz , and the introduction of the magnetic field b z brings in only trivial changes (in sec 5) 38 Contrary to the switching on, this switching off need not be performed suddenly since m …”

Section: The Magnetmentioning

confidence: 99%

“…Indeed, these questions have escaped the realm of speculation owing to progresses in experimental physics which allow to tackle the foundations of quantum mechanics from different angles. Not only Bell's inequalities [27,34,36] but also the Greenberger-Horne-Zeilinger (GHZ) logical paradox [37] have been tested experimentally [38]. Moreover, rather than considering cases where quantum interference terms (the infamous "Schrödinger cat problem" [8,13,39]) vanish owing to decoherence processes [40], experimentalists have become able to control these very interferences [41], which are essential to describe the physics of quantum superpositions of macroscopic states and to explore the new possibilities offered by quantum information [22,42].…”

Section: General Features Of Quantum Measurementsmentioning

confidence: 99%

See 1 more Smart Citation

Understanding quantum measurement from the solution of dynamical models

Allahverdyan¹,

Balian²,

2013

View full text Add to dashboard Cite

The quantum measurement problem, to wit, understanding why a unique outcome is obtained in each individual experiment, is currently tackled by solving models. After an introduction we review the many dynamical models proposed over the years for elucidating quantum measurements. The approaches range from standard quantum theory, relying for instance on quantum statistical mechanics or on decoherence, to quantum-classical methods, to consistent histories and to modifications of the theory. Next, a flexible and rather realistic quantum model is introduced, describing the measurement of the z-component of a spin through interaction with a magnetic memory simulated by a Curie-Weiss magnet, including N 1 spins weakly coupled to a phonon bath. Initially prepared in a metastable paramagnetic state, it may transit to its up or down ferromagnetic state, triggered by its coupling with the tested spin, so that its magnetization acts as a pointer. A detailed solution of the dynamical equations is worked out, exhibiting several time scales. Conditions on the parameters of the model are found, which ensure that the process satisfies all the features of ideal measurements. Various imperfections of the measurement are discussed, as well as attempts of incompatible measurements. The first steps consist in the solution of the Hamiltonian dynamics for the spin-apparatus density matrixD(t). Its off-diagonal blocks in a basis selected by the spin-pointer coupling, rapidly decay owing to the many degrees of freedom of the pointer. Recurrences are ruled out either by some randomness of that coupling, or by the interaction with the bath. On a longer time scale, the trend towards equilibrium of the magnet produces a final stateD(t f ) that involves correlations between the system and the indications of the pointer, thus ensuring registration. AlthoughD(t f ) has the form expected for ideal measurements, it only describes a large set of runs. Individual runs are approached by analyzing the final states associated with all possible subensembles of runs, within a specified version of the statistical interpretation. There the difficulty lies in a quantum ambiguity: There exist many incompatible decompositions of the density matrixD(t f ) into a sum of sub-matrices, so that one cannot infer from its sole determination the states that would describe small subsets of runs. This difficulty is overcome by dynamics due to suitable interactions within the apparatus, which produce a special combination of relaxation and decoherence associated with the broken invariance of the pointer. Any subset of runs thus reaches over a brief delay a stable state which satisfies the same hierarchic property as in classical probability theory; the reduction of the state for each individual run follows. Standard quantum statistical mechanics alone appears sufficient to explain the occurrence of a unique answer in each run and the emergence of classicality in a measurement process. Finally, pedagogical exercises are proposed and lessons for future works on m...

show abstract

Section: The Magnetmentioning

confidence: 99%

Section: General Features Of Quantum Measurementsmentioning

confidence: 99%

Understanding quantum measurement from the solution of dynamical models

Allahverdyan¹,

Balian²,

2013

View full text Add to dashboard Cite

show abstract

“…22, has been used in the observation of multi-photon entanglement 24 23− , and also in a recent proposal for spin-flip-error correction in quantum communication 25 .…”

mentioning

confidence: 99%

“…With the techniques developed in experiments on quantum teleportation 13 , 12 and multi-photon entanglement 24 23− , an immediate experimental verification of our purification protocol should be possible.…”

mentioning

confidence: 99%

Entanglement purification for quantum communication

Pan

Simon

Brukner

et al. 2001

Nature

Self Cite

742

701

View full text Add to dashboard Cite

“…The literature on this remarkable sequence of experiments is extensive, but see, for example, Ansmann et al (2009) ;Cabello, Estebaranz, and García-Alcaine (1996);Fuchs (2010); Giustina et al (2013);Pan, Bouwmeester, Daniell, Weinfurter, and Zeilinger (2000); Rowe et al (2001);Salart, Baas, van Houwelingen, Gisin, and Zbinden (2008);and Weihs, Jennewein, Simon, Weinfurter, and Zeilinger (1998). A gentle introduction to this literature is given by Mermin (1985).…”

Section: Barton Andersonmentioning

confidence: 99%

Probing the interface theory of perception: Reply to commentaries

2015

View full text Add to dashboard Cite

We propose that selection favors nonveridical perceptions that are tuned to fitness. Current textbooks assert, to the contrary, that perception is useful because, in the normal case, it is veridical. Intuition, both lay and expert, clearly sides with the textbooks. We thus expected that some commentators would reject our proposal and provide counterarguments that could stimulate a productive debate. We are pleased that several commentators did indeed rise to the occasion and have argued against our proposal. We are also pleased that several others found our proposal worth exploring and have offered ways to test it, develop it, and link it more deeply to the history of ideas in the science and philosophy of perception. To both groups of commentators: thank you. Point and counterpoint, backed by data and theory, is the essence of science. We hope that the exchange recorded here will advance the scientific understanding of perception and its evolution. In what follows, we respond to the commentaries in alphabetical order.Keywords Bayesian inference . Parameter estimation . Perceptual categorization and identification . Visual perception . Categorization Barton AndersonWhere does fitness fit in theories of perception? doi:10.3758/ s13423-014-0748-5Overview (1) Anderson argues that, BFor the games they considered, the only 'force' of adaptation was through natural selection. In such cases, perception should indeed track utility directly. But the same doesn't hold if animals can adjust their behavior to meet homeostatic demands on ontogenetic time scales.^We reply that time scale and ontogenetics are irrelevant to the issue of tracking utility. (2) Anderson says, BIf the 'payoff' function of homeostasis is nonmonotonic, as is typical, then the perceptual response needs to track resources monotonically so that an animal can know to adapt its behavior to achieve homeostasis.^We explain why this is false. (3) Anderson argues that our characterization of perceptual strategies using an abstract set of world states W assumes a BGod's eye view^of the world and Bmisses a fundamental point about what constitutes both the objects of science and experience; the fundamental elements of system description in science are observables, not unspecifiable 'world states'.^We explain how our abstract approach serves to avoid a God's eye view, and how it engages the standard interaction of theory, observables, and experiments that is central to science. (4) Anderson claims that our argument for redefining the notion of perceptual illusion is that, BSince we have no access to the 'true' world states, it is impossible to ever determine whether perception is veridical (in their sense) or in error, which leads them to the conclusion that such distinctions can only be defined in terms of adaptive behavior.^We explain that this is not our argument, and then explain what our real argument is. (5) Anderson proposes to define veridical perception in terms of the coherence between different observables. We explain why this is misleading an...

show abstract

Experimental test of quantum nonlocality in three-photon Greenberger–Horne–Zeilinger entanglement

Cited by 1,099 publications

References 27 publications

Understanding quantum measurement from the solution of dynamical models

Understanding quantum measurement from the solution of dynamical models

Entanglement purification for quantum communication

Probing the interface theory of perception: Reply to commentaries

Contact Info

Product

Resources

About