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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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Video of Double Slit Experiment Observer Effect

I have been watching a lot of videos of the double slit experiment and trying to wrap my head around it. I found examples of where the experiment has been done, however the videos cut out and only ...
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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 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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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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Mathematical formulation of partial wave function collapse

If given a wave function which is an element of a Hilbert space $\mathcal{H}$ which is a tensor product of two other Hilbert spaces $\mathcal{H}_1\otimes\mathcal{H}_2$, how do you formulate ...
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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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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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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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Finding an energy of a particle in an infinite potential well

This question arises from a discussion I recently had with my friend. We were talking about a particle in an infinite potential well. The particle is in an arbitrary wavefunction $\Psi$. When one ...
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What is the physical basis of Born's interpretations?

Did anyone has any idea how Born came up with the probabilistic interpretation of quantum mechanics. It is by all means very bizarre. And then it leads to the idea of copenhagen interpretation. Also ...
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Wave function collapse of entangled photons?

If we have two entangled photons then they are described by the same wave function. But if I measured the position of the signal photon and it collapses into a position, would the idler photons ...
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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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Could we interpret search for the Pitch as a process similar to the collapse of the wave function?

According to Wikipedia: In quantum mechanics, wave function collapse is said to occur when a wave function—initially in a superposition of several eigenstates—appears to reduce to a single eigenstate ...
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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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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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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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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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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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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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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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Double sit experiment and Uncertainty

If we try to an electron with a high energy photon, we precisely detect its position, while its momentum becomes totally uncertain. On the other hand, if we detect it using a low energy photon, its ...
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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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Wave function collapse when it is spread over large space

Imagine there is an atom whose wavefunction is uniformly spread across a whole room. Can we estimate the time it will take for the atom interact with other atoms in the room leading to the collapse of ...
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can any eigenfunction be normalizable ? If not why? and If yes How?

As it is told in quantum mechanics that a wave function has to be normalizable otherwise it won't express any physical situation. And this is too known that measurement or observations collapses ...
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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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How Do We Know That It Is Measurement

How do we know that it is measurement that collapses wave functions, and not just the other forces at play in all of the different measurement devices that collapse wave functions? Thanks