# Tag Info

1

If it behave like a particle would this means the animal is conscious like a human? No, it would simply mean that animal's sensing systems and interaction with the photon is well modelled by a quantum observable. You may not have met this word before; in short, an observable is a mathematical model for the measurement itself: it is a operator that ...

5

The claim that during the experiment they let the detector on but did not stored the data so it showed waves, only when they stored the data it showed as particle. is inaccurate and inconsistent with quantum mechanics. In a double-slit experiment, any device that can even in principle provide which-way information will destroy the interference ...

0

In standard EPR experiment, when detectors answer only match or not match , there is no classical solution. But experiments show other cases where one or both detectors don't detect their photon. Only 75% are detected on each arm. Read inside the papers, not only the abstacts. If you take account of the other options, there are classical probabilistic ...

2

$\newcommand{\ket}[1]{\lvert #1 \rangle}$You seem to be confused about what measuring an operator means. Let $A,B$ be two commuting self-adjoint operators as in your question, and let $\{u_n\}$ be a basis of simultaneous eigenvectors, that is $$A\ket{u_i} = a_i \ket{u_i} \ \vee \ B\ket{u_i} = b_i \ket{u_i}$$ Now, a generic state $\psi$ can be written as  ...

8

It's tempting to think of the light as a little ball (the photon), and since little balls have a definite position the little ball has to be in a superposition of a state where it goes through one slit and a state where it goes through the other. However this is not a good description of what actually happens. The light is not a photon, and it's not a wave ...

1

In classical mechanics, each body has an exact position at all times (and hence an exact speed given by its derivative, and the equivalent quantities for rotary motion). To understand the difference to quantum mechanics, think of it as wave mechanics: Each body is described by a wave(function) and properties such as position or speed are only defined to the ...

1

Roughly speaking, and restricting to particles for now, a classical trajectory is a set of exact positions and corresponding velocities (or momenta) of the particle, which (usually) change over time. In quantum mechanics, the uncertainty principle says that it is not possible to know simultaneously the exact position and momentum of the particle, and so it ...

0

If you want to study how to move the boundaries and correctly get the right answers, you can study the SSC (Sufficiency of Subspace Correlations) theorem. There is an entire interpretation (called the Ithaca Interpretation) built around it, and it sounds like exactly what you are describing. You can look up Mermin, or "correlations without correlata" if ...

2

Indeed, in non-relativistic quantum mechanics, the equation of evolution of the quantum state is given by Schrödinger's equation and measurement of a state of particle is itself a physical process and thus, should and is indeed be governed by the Schrödinger's equation. Indeed, people like to predict probabilities using Born's rule, and sometimes they do ...

1

Yes. Nonweak measurements correspond to Hermitian (or self adjoint) operators. The results are 1) an eigenvalue and 2) you project the state vector onto the corresponding eigenspace. The projections onto different eigenspaces produce eigenvectors with different eigenvalues, and eigenvectors of a symmetric operator with different eigenvalues are orthogonal. ...

0

Yes the wave function "collapses" after Alice measures her part. I am not sure what you call the Von-Neumann collapse. Here you have a bipartite measurement with only one photon. And I guess the steering thing had never been done before with only one photon. No there's nothing profound.

3

Actually, I think that what you ask for is impossible, or at least not as physically meaningful as one might expect. This is because of the following fact: any situation in which you have unequal amplitudes between two states can be re-formulated as a bunch of states of equal amplitude. So, as a result, it is possible to describe any state as coming from a ...

0

To say that the spin "is pointed along the $x$-axis [and will] be reoriented into the $\pm z$-direction" isn't quite right to begin with. A quantum-mechanical spin doesn't exactly point in a specific direction; it's just that it only has a definite projection onto (at most) a single axis. Indistinguishable particle questions aside, you can say that an ...

2

I don't understand your example, when you say you have 5 possibilities and the second clearly has two different final outcomes. It seems you want to find a flaw in MWI, and I want to warn you that you going to fail, because it is an interpretation, not a separate theory, so all you can hope for is to show that all of QM is internally inconsistent (unlikely) ...

0

Free-bits have nothing to do with it. We deal with van Inwagen by the following argument. Determinism does not rule out free will, because free will within a system is necessarily deterministic. Otherwise it would be totally useless and would not be able to observe anything, because it would not be able to influence the apparatus used for observation. In ...

Top 50 recent answers are included