Questions tagged [quantum-foundations]
19 questions
13
votes
5 answers
Why quantum entanglement for a non-local object needs explanation?
I am a little confused about the usual explanations about quantum entanglement.
In the Schrödinger picture, the state vector evolves in time.
In the Heisenberg picture, the state vector does not evolve in time.
In either case, there is no mention of…
VVM
- 585
12
votes
5 answers
Can the collapse of the wave function be modelled as a quantum system on its own?
Imagine I have an observer $\mathcal O$, a quantum system $\mathcal S$ with Hilbert space $V_{\mathcal S}$, a Hamiltonian $H$, a self-adjoint operator $A$ acting on $V_{\mathcal S}$. The system is in the (normalized) state $|\psi_0\rangle$ at time…
Lorenzo Pompili
- 385
7
votes
4 answers
Confusion around Bell's Theorem and Locality
I recently got interested in foundational aspects of quantum mechanics and I have some questions:
Bell's theorem proves that any local, deterministic theory with statistical independence can't account for certain observed correlations. The standard…
Davyz2
- 779
- 2
- 15
4
votes
2 answers
Why does the path integral formulation not provide an ontological basis for quantum theory?
I have looked at several books on the foundations of quantum theory and found that the path integral formulation is hardly ever discussed in detail. I find this surprising because this formulation of quantum mechanics quite naturally leads to…
Girish Kulkarni
- 742
4
votes
4 answers
Understanding superdeterminism
I was reading about superdeterminism and it was a bit counter-intuitive. The idea of having a hidden variable on the measurement device is very rational. For example, if we emit light to a constrained electron like in a hydrogen atom, only photons…
user123456789
- 61
- 4
3
votes
1 answer
Significance of Pusey-Barrett-Rudolph (PBR) Theorem
I recently read the PBR Theorem and from what I understand it addresses one of the old problems regarding quantum state completeness, one for which there are three possibilities (correct me if am wrong here):
A physical state $\lambda$ corresponds…
Davyz2
- 779
- 2
- 15
3
votes
2 answers
Relation between Locality and Determinism
In a previous question I asked, I was confused about how can you refuse determinism/realism in Bell's theorem without also refusing relativistic locality. I would like to understand where my following argument goes wrong.
Suppose that a physical…
Davyz2
- 779
- 2
- 15
3
votes
6 answers
What was the fallacy in EPRs chain of arguments?
Let's say, there is an entangled system of two electrons with opposite spins; The joint system is in a state of eigenvectors for z-Spin ( $S_z$) with both particles far away from each other:
$$|\Psi\rangle = \frac{1}{\sqrt{2}}(| +\rangle | -\rangle…
MichaelW
- 1,511
3
votes
7 answers
Is electron a quantum observer?
An electron can receive information and can modify internal state according to it. Is electron itself a quantum observer or it's applicable to classic objects only?
ZZ Wave
- 67
2
votes
1 answer
Consistent histories vs. relational interpretation and Qbism
I hope that my question will be suitable for this forum: I would like to understand the difference between the so called consistent history approach to QM and several other interpretations. In this discussion it is remarked that similarly to the…
truebaran
- 315
1
vote
2 answers
How can the Copenhagen and Everett interpretations of quantum mechanics make the same predictions?
Suppose we have a spin $\frac{1}{2}$ particle in the spin-up state along the $z$-axis, $\lvert \uparrow \rangle$, and after $t$ seconds of evolution under the Schrodinger equation it is in state $\alpha\lvert \uparrow \rangle + \beta\lvert…
MBar2269
- 103
1
vote
1 answer
Quantum Behavior and Negativity of Wigner Functions
Let us consider a scenario where we have a dataset $\mathbf{X}$, which is a collection of vectors $\mathbf{x}_i \in \mathbb{R}^n$. We encode each component $x_j \in \mathbb{R}$ of $\mathbf{x}$ in a coherent state $|x_j\rangle$ (not a position…
Song of Physics
- 990
1
vote
1 answer
Do objective collapse equations actually collapse the state?
Why are objective collapse theories stated to collapse the state from a superposition to a single eigenstate (corresponding to the measured eigenvalue)? For this discussion, we are focusing on the mathematics of the equations, not on any…
Jahn Dorian
- 494
1
vote
1 answer
Bell-Kochen-Specker theorem impact on realistic hidden-variable theories
I've read the paper 'Generalizations of Kochen and Specker’s theorem and the effectiveness of Gleason’s theorem', where it says that non-contextual hidden-variable theories are ruled out by a theorem of Bell (1966), which is stated as 'There does…
Studentu
- 140
1
vote
2 answers
Measurement problem and precise mathematical calculation
The infamous measurement problem is a problem in the foundations of quantum mechanics: different people have different views how to understand this problem: some people even deny that there is any problem after all: from the same reason there will…
truebaran
- 315