Questions tagged [wavefunction-collapse]

Wavefunction collapse amounts to the apparent reduction of a wavefunction consisting of a superposition of several eigenstates to a single eigenstate (by "observation"). It underlies measurement in quantum mechanics and connects the wave function with classical observables, in a thermodynamically irreversible interaction with a classical environment, normally disfavoring future QM interference.

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How can the pre-measurement be fulfilled?

In the decoherence program, the pre-measurement refers to the evolution in which the system and apparatus form a Schmidt state. In Maximilian Schlosshauer's review article(2005), I read "the linearity ...
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Published claimed falsifications of objective collapse theories

My main source of information about objective collapse theories is this review article by Bassi et al. There seem to be some problems with the theory that its practitioners readily admit to, such as ...
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How are weak measurements taken into account in collapse models?

Collapse models have been introduced to solve the measurement problem in quantum mechanics. In collapse models the localization of wavefunction is not considered to be due to any kind of measurement ...
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Wave function collapse for experimental quantum state preparation

Has the John von Neumann projection, or the wave function collapse, been used in the experimental preparation of quantum states? As an illustration, for a pair of EPR-type entangled 2-level atoms $$|\...
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Quantum Observation

Bear with me if I present a lack of knowledge - QM is not my field. There's a common notion in QM that until a particle is observed (measured), its properties are not definite, but rather are spread ...
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In the electron's double slits experiment, what causes the electron's wave function to collapse at the screen?

In this figure from Wikipedia, we know that electron's wavefunction collapse at screen F, causing an interference pattern. Does it mean that in this case when the wavefront arrives at the screen, the ...
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What influence has quantum-gravity on the “collapse” of a free wave-function belonging to one of many in the free quantum field?

When in Quantum Field Theory a free field has an interaction with quantum-gravity (gravitons) will this interaction has as a result that wavefunctions (or better put, one of the many) will collapse?
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Bohmian vs Copenhagen Interpretation

Is there any experiment that could settle the debate between De Broglie - Bohm Pilot Wave Theory and the Copenhagen Interpretation?
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What is an interaction (Quantum Mechanics) and is the wavefunction collapse an objective phenomenon?

First of all, I'm an undergrad. student of engineering physics, so I must explicit my lack of formal knowledge on the subject and total confusion with its implications. I also understand it may be ...
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Penrose experiment

I just read about Penrose interpretation theory about the wave function collapse: https://en.wikipedia.org/wiki/Penrose_interpretation, which could be confirmed/infirmed by the following experiment: ...
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Is it certain that “experimental physics has not already detected an unexpected spontaneous collapse”

The WikiPedia page for the Ghirardi–Rimini–Weber theory states that "experimental physics has not already detected an unexpected spontaneous collapse". Is this really true? What would be the ...
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Wave function collapse, EPR paradox and information transfer

For a classical formulation of the EPR paradox, two particles are produced, with total momentum zero and separated by a long distance. So say we measure the momentum of one particle first, and measure ...
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76 views

How is the wavefunction of an electron affected by the presence of an atom at the slits in the double-slit experiment?

I'm reading on page 107 of this Van Kampen's paper that the apparatus influences the electron even without detecting it. The interference pattern we obtained ...
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Can we measure without collapsing (too much) the wave function, according to decoherence theory?

According to decoherence theory, the collapse of the wave function is a continuous process due to interaction with environment. In a measure, there are interactions with photons (for example). Can we ...
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Decoherence time of quantum decoherence and appearance of wavefunction collapse

If decoherence time of quantum decoherence is zero, or if off-diagonal elements of density matrix of quantum system (without environment considered) vanished immediately after interaction with ...
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Quantum eraser experiment with unbalanced interfereometers

In quantum eraser experiments, which path information is made available and then destroyed before the photon hits the screen. Now, say we had an experiment in which a photon is sent to a double slit ...
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How does the apparatus in QM cause the interruption of the interference pattern in the Pilot-Wave theory?

In the wikipedia page, it is written that the apparent collapse of the wave function in the Pilot-Wave theory happens because "the environment registering the detection effectively separates the ...
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Different realizations of single-electron double-slit experiment

Recently I was reading about the real world realization of the double-slit experiment, in which we shoot single electrons. The final detection on the rear screen is done "by collecting the transmitted ...
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What is algebraic structure, operation or relation explains relationship between the 2 diagonal terms of the 2 density matrices?

Quantum decoherence therefore prescinds from the observer and from the measurement process in a certain way preceding it and simulating the collapse of the wave function. In particular, "...
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Does the energy and/or mass of an electron change during the act of measurement and so the wavefunction collapse?

In the double-slit experiment, if we want to know which slit did the electron go through, we have to use a laser that gives an energy to the electron. Now, I have two questions: 1. Does the energy of ...
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Instantaneous quantum features

Two of the most striking quantum oddities are entanglement and the wave-function collapse or state vector reduction. Firstly, quantum entanglement is the quantum phenomena involving states of ...
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Will there be two cats in the box (superposition) if I use virtual particles (magnetic field) to open the box in Schrodinger's experiment?

I have read this question: How does a Wavefunction collapse? Where annav says: More specifically, what conditions cause a wavefunction for a quantum particle to collapse? A ...
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64 views

Can wave collapse during measurement be avoided with a better experiment / measurement apparatus?

Or to restate the question, does quantum mechanics or the quantum field theory state or imply that we can only observe the wave in a collapsed state? And if they don't, do we have any promising ...
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Collapse of quantum state after measurement of degenerated eigenvalue (From textbook Shankar) (Closed)

I want to ask an easy question from Problem 4.2.1, Quantum Mechanics(2nd) by Shankar. Let's say Operators, $L_{x}$, $L_{y}$, $L_{z}$ are $$L_{x}$ = $1/2^{1/2}$ $\begin{pmatrix} 0& 1 &0 \\ ...
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Decoherence/wave function collapse between entangled photon pair

If photon 1 and 2 are position entangled and they go in different directions, would making a measurement on photon 1 effect photon 2? If photon 1 is detected can photon 2 still create interference?
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What are the exact setups to observe a wave function and its collapsed state?

I was reading this article: http://io9.com/5528321/how-smart-do-you-need-to-be-to-collapse-a-wave-function and I need some clarification on the experiment setup. My current understanding is that if ...
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Examples of symmetric field collapse to produce asymmetry

It would really help me with an idea I have if I could see how something such as a symmetric field could collapse to something asymmetric. I know that if $x$ occures before $y$ is symmetric, then $y$ ...
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Decoherence, collpse, and WHEN does the collapse occur?

The idea that decoherence stands behind the so-called collapse (reduction) of the wave-function doesn't seem satisfactory. Consider a quantum particle whose wave-function is of the form (1) $$\left|...
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Quantum mechanical measurement

Suppose, a particle has non zero probability to be in any between x = 1 and x = 10. Let, we measure its position with a very low energy photon. It will collapse it’s wave function, since it disturbs ...
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105 views

Minimum criteria for quantum state dissolution

What are the minimum conditions required to cause the colapse of the quantum state ? Or, what forces/equations determine when an object (for instance an electron) is forced out of its quantum state in ...
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282 views

What the wave function looks of a particle in the infinite square well looks like after collapse for measurements of position and energy

Consider a particle in a the infinite square well from x=0 to x=L. At t=to, I make a measurement of position and get x=L/2. What is the resulting wave function at t=to? My understanding, from reading, ...
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291 views

Wave Function Collapse and Which Path Information

From what I understand, wave function collapse occurs when a photon/wave/particle/whatevertheheckitis which was previously in a superposition of states, collapses to one state. Now, in a double slit ...
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Wave-function collapse query

A distant star emits photons towards Earth, where they can be detected and observed, however there is a very dense object (a galaxy) directly between the distant light source and our observation ...
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Does the anthropic principle rule out the many worlds interpretation of quantum mechanics?

TAP says that the set of observations of things we have is not a random set of all things; there is observer bias. TMWI of QM says that the universe splits to accommodate every possible collapse ...