Questions tagged [quantum-mechanics]
Quantum mechanics describes the microscopic properties of nature in a regime where classical mechanics no longer applies. It explains phenomena such as the wave-particle duality, quantization of energy, and the uncertainty principle and is generally used in single-body systems. Use the quantum-field-theory tag for the theory of many-body quantum-mechanical systems.
10 questions from the last 7 days
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Does pre-shared entanglement eliminate the need for a classical channel? [duplicate]
I've been thinking about a quantum communication device and have a specific question about the no-communication theorem. I used AI to help me write this, btw, as I was having a hard time wording this ...
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Does quantum non-commutativity constrain the Tomita-Takesaki modular flow to be one-dimensional for physically realizable observer states?
The Tomita-Takesaki theorem, applied to a faithful normal state $ρ$ on a von Neumann algebra, always produces a one-parameter automorphism group — mathematically, this is built into the theorem. My ...
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Quantum Entanglement and No-communication theorum [closed]
I am trying to conceptually find a workaround for FTL communications. My idea is to use quantum entanglement to transmit information, but differently than currently done.
Basically, instead of ...
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8
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1
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How does $\hat{a}_j^\dagger \hat{a}_k$ act on anyonic Fock states?
I am familiar with bosonic models, where the annihilation and creation operators act on Fock states in the "usual" way:
\begin{equation}
\hat{b}_j^\dagger \hat{b}_k \, |n_j, n_k\rangle = \...
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3
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Conservation of Energy or also Number of Atoms?
For those who are experts in science or quantum science, I want to ask, has the number of atoms in the universe from the beginning until now stayed the same or could it have increased? As far as I ...
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1
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Is continuity equation mean to be solved?
Honestly i never see any solving continuity equation. I only see examples that EM or QM can derive the continuity equation, but never see solving it. Is the equation means to be solved? Or is it just ...
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6
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1
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Speed of light as limit of information or limit of energy transfer
We say that the speed of light is the limit at which information can be transferred and resolve the EPR issue with non-determinism and how effective information transfer is still limited to $c$.
This ...
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2
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What does the conservation of probability density in QM mean?
This question can go in many directions. Let me clarify which direction I am asking about. The mathematics of the conservation is often introduced by $|{\psi(t)}|^2$; it has to remain unchanged under ...
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2
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63
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Why does the thermodynamic limit give Type II Von Neumann algebra for $\theta=\pi/4$ but Type III for $\theta\neq\pi/4$ in entangled spin systems?
I am trying to understand a point from Section II~E of the lecture notes ``Lectures on entanglement, von Neumann algebras, and emergence of spacetime''.
Consider two copies (labeled $R$ and $L$) of a ...
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Angular Momentum conservation in superfluids
If we rotate a superfluid above the critical temperature and then cool it down to a superfluid transition the conservation of angular momentum will create vortices. This is fine because as long as we ...
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