scholarly journals Making Mistakes Saves the Single World of the Extended Wigner’s Friend Experiment

2021 ◽  
Author(s):  
Szymon Łukaszyk
Keyword(s):  
Quantum Theory ◽  
Thought Experiment ◽  
Physical Space ◽  
Entangled State ◽  
Freedom Of Choice ◽  
Identity Of Indiscernibles ◽  
Quantum Domain ◽  
Wigner’S Friend ◽  
Ugly Duckling ◽  
Single World

Abstract The Extended Wigner’s Friend thought experiment comprising a quantum system containing an agent who draws conclusions, upon observing the outcome of a measurement of a qubit prepared in two non-orthogonal versions by another agent led its authors to conclude that quantum theory cannot consistently describe the use of itself. It has also been proposed that this thought experiment is equivalent to coherent entangled state (Bell type) experiments. It is argued in this paper that the assumption of the freedom of choice of the first Wigner’s friend invalidates such equivalency. It is also argued that the assumption of locality (physical space) introduces superfluous identity of indiscernibles metric axiom, which is invalid in quantum domain and generally disproven by the Ugly duckling mathematical theorem.

scholarly journals A no-go theorem for the persistent reality of Wigner’s friend’s perception

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Philippe Allard Guérin ◽  
Veronika Baumann ◽  
Flavio Del Santo ◽  
Časlav Brukner
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Thought Experiment ◽  
Joint Probability ◽  
Joint Probability Distribution ◽  
Initial State ◽  
Interpretations Of Quantum Mechanics ◽  
Present Information ◽  
Wigner’S Friend ◽  
Measured System

AbstractThe notorious Wigner’s friend thought experiment (and modifications thereof) has received renewed interest especially due to new arguments that force us to question some of the fundamental assumptions of quantum theory. In this paper, we formulate a no-go theorem for the persistent reality of Wigner’s friend’s perception, which allows us to conclude that the perceptions that the friend has of her own measurement outcomes at different times cannot “share the same reality”, if seemingly natural quantum mechanical assumptions are met. More formally, this means that, in a Wigner’s friend scenario, there is no joint probability distribution for the friend’s perceived measurement outcomes at two different times, that depends linearly on the initial state of the measured system and whose marginals reproduce the predictions of unitary quantum theory. This theorem entails that one must either (1) propose a nonlinear modification of the Born rule for two-time predictions, (2) sometimes prohibit the use of present information to predict the future—thereby reducing the predictive power of quantum theory—or (3) deny that unitary quantum mechanics makes valid single-time predictions for all observers. We briefly discuss which of the theorem’s assumptions are more likely to be dropped within various popular interpretations of quantum mechanics.

Entanglement

2017 ◽  
Author(s):  
Richard Healey
Keyword(s):  
Quantum Theory ◽  
Quantum State ◽  
Physical Condition ◽  
Physical System ◽  
Polarization State ◽  
Quantum Systems ◽  
Ghz State ◽  
Mathematical Representation ◽  
Entangled State ◽  
Physical Relation

Often a pair of quantum systems may be represented mathematically (by a vector) in a way each system alone cannot: the mathematical representation of the pair is said to be non-separable: Schrödinger called this feature of quantum theory entanglement. It would reflect a physical relation between a pair of systems only if a system’s mathematical representation were to describe its physical condition. Einstein and colleagues used an entangled state to argue that its quantum state does not completely describe the physical condition of a system to which it is assigned. A single physical system may be assigned a non-separable quantum state, as may a large number of systems, including electrons, photons, and ions. The GHZ state is an example of an entangled polarization state that may be assigned to three photons.

scholarly journals Experimental test of local observer independence

2019 ◽  
Vol 5 (9) ◽  
pp. eaaw9832 ◽  
Author(s):  
Massimiliano Proietti ◽  
Alexander Pickston ◽  
Francesco Graffitti ◽  
Peter Barrow ◽  
Dmytro Kundys ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Scientific Method ◽  
Free Choice ◽  
Empirical Investigation ◽  
State Of The Art ◽  
Thought Experiment ◽  
Type Inequality ◽  
Repeated Measurements ◽  
Wigner’S Friend ◽  
Local Observer

The scientific method relies on facts, established through repeated measurements and agreed upon universally, independently of who observed them. In quantum mechanics the objectivity of observations is not so clear, most markedly exposed in Wigner’s eponymous thought experiment where two observers can experience seemingly different realities. The question whether the observers’ narratives can be reconciled has only recently been made accessible to empirical investigation, through recent no-go theorems that construct an extended Wigner’s friend scenario with four observers. In a state-of-the-art six-photon experiment, we realize this extended Wigner’s friend scenario, experimentally violating the associated Bell-type inequality by five standard deviations. If one holds fast to the assumptions of locality and free choice, this result implies that quantum theory should be interpreted in an observer-dependent way.

scholarly journals POPPER'S THOUGHT EXPERIMENT REINVESTIGATED

2012 ◽  
Vol 10 (03) ◽  
pp. 1250033 ◽  
Author(s):  
CHRIS D. RICHARDSON ◽  
JONATHAN P. DOWLING
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Thought Experiment

Popper's original thought experiment probed some fundamental and subtle rules of quantum mechanics. He claimed that quantum mechanics was incomplete and devised an experiment to prove it. Two experiments have directly and indirectly tested Popper's hypothesis, and they provide some evidence that Popper's prediction may have been correct. The equations governing these two experiments and Popper's thought experiment will be derived from basic quantum principles. The experimental constants will be inputted and it will show that the two experiments reinforce each other and agree completely with quantum theory.

The so-called fourth indeterminacy relation

1970 ◽  
Vol 48 (11) ◽  
pp. 1410-1411 ◽  
Author(s):  
Mario Bunge
Keyword(s):  
Quantum Theory ◽  
Thought Experiment ◽  
Time And Energy

The indeterminacy relation between time and energy, suggested by Bohr on the basis of a thought experiment, is shown not to belong to the quantum theory. It is argued that the incorporation of that formula into a theory would require a basic departure from present day physics, consisting in representing time by a suitable operator. It is suggested that the formula be dropped altogether.

scholarly journals Einstein-Podolsky-Rosen correlation seen from moving observers

2003 ◽  
Vol 3 (3) ◽  
pp. 224-228
Author(s):  
H. Terashima ◽  
M. Ueda
Keyword(s):  
Quantum Theory ◽  
Quantum Communication ◽  
Relativistic Quantum ◽  
Entangled State ◽  
Local Correlation ◽  
Relativistic Quantum Theory ◽  
Gedanken Experiment ◽  
Einstein Podolsky Rosen ◽  
Non Local ◽  
Epr Pair

Within the framework of relativistic quantum theory, we consider the Einstein-Podolsky-Rosen (EPR) gedanken-experiment in which measurements of the spin are performed by moving observers. We find that the perfect anti-correlation in the same direction between the EPR pair no longer holds in the observers' frame. This does not imply a breakdown of the non-local correlation. We explicitly show that the observers must measure the spin in appropriately chosen different directions in order to observe the perfect anti-correlation. This fact should be taken into account in utilizing the entangled state in quantum communication by moving observers.

scholarly journals Does Observation Create Reality?

2021 ◽  
Vol 19 (1) ◽  
pp. 11-15
Author(s):  
Daegene Song
Keyword(s):  
Energy Transfer ◽  
Quantum Theory ◽  
Quantum System ◽  
Quantum Entanglement ◽  
Physical System ◽  
Information Transfer ◽  
Thought Experiment ◽  
Particle Creation ◽  
Physical World ◽  
Quantum Vacuum

It has been suggested that the locality of information transfer in quantum entanglement indicates that reality is subjective, meaning that there is an innate inseparability between the physical system being observed and the conscious mind of the observer. This paper attempts to outline the relation between macroscopic and microscopic worlds in the measurement process in regards to whether observation creates reality. Indeed, the Maxwell's demon thought experiment suggests a correlation between a microscopic (quantum) system and a macroscopic (classical) apparatus, which leads to an energy transfer from the quantum vacuum to the physical world, similar to particle creation from a vacuum. This explanation shows that observation in quantum theory conserves, rather than creates, energy.

scholarly journals Emergence of Objective Reality in an Irreversible Friend thought Experiment

2021 ◽  
Author(s):  
Robert Shuler
Keyword(s):  
Thought Experiment ◽  
Hidden Variables ◽  
Ensemble Member ◽  
Irreversible Processes ◽  
Many Worlds ◽  
Objective Reality ◽  
Objective World ◽  
The Public ◽  
Wigner’S Friend ◽  
The Many

Background: Recently some photon models of a Wigner's friend experiment have led investigators to suggest objective reality does not exist, and to publish non-academic articles with such claims. The public is not equipped to evaluate the severe limitations of these experiments. The separation of Wigner from the experiment and use of only reversible coherent processes for the friend allow operations that are not possible in ordinary reality according to the latest quantum research. Methods: We suggest directly testing the implied claim that objective reality, including incoherent objects with irreversible non-destructive memory, can be held in superposition. We suspect it will fail, but provide for a graduated approach that may discover something about the conditions for superposition collapse. To this end we design a thought experiment to model the objective world, investigating under what conditions experimenters in the same world (ensemble member) will be able to record a result and find it does not appear to change. An observer has a viewing apparatus and a memory apparatus. A second uncorrelated viewer of the same recorded result is employed to obtain objectivity. By hypothesis the uncorrelated second viewer obtains the same view of the measurement record as the first observer. There are not two measurements. This is not an investigation of hidden variables. Results: To model the objective world, incoherent and irreversible processes must be included. To test for superposition, coherence has to be established. These seem to present a contradiction. Conclusions: The thought experiment has suggested new places to look other than size for the origin of objective reality from the quantum world, casts doubt on the Many-Worlds interpretation, and provides a method of testing it.

A Fractal Universe and the Identity of Indescernibles

2019 ◽  
Vol 12 ◽  
pp. 86-94
Author(s):  
Matteo Casarosa ◽  
Keyword(s):  
Thought Experiment ◽  
Thought Experiments ◽  
Relational Theory ◽  
Identity Of Indiscernibles ◽  
New Thought ◽  
Classical Sense ◽  
Better Than

The principle of Identity of Indiscernibles has been challenged with various thought experiments involving symmetric universes. In this paper, I describe a fractal universe and argue that, while it is not a symmetric universe in the classical sense, under the assumption of a relational theory of space it nonetheless contains a set of objects indiscernible by pure properties alone. I then argue that the argument against the principle from this new thought experiment resists better than those from classical symmetric universes three main objections put forth against this kind of arguments.

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