# Tagged Questions

A basic principle of solutions of *linear* differential (often wave) equations, ensuring that the sum ("superposition") of two solutions is automatically a solution as well. Conversely, solutions (amounting to quantum states in quantum mechanics, since the SchrÃ¶dinger equation is linear) can be ...

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### What is the Meaning of the Superposition Principle

I am a bit confused as to what the superposition principle actually means. Does it merely mean that you can express any given state as the linear combination of two vectors? If so, isn't that kind of ...
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### Linear combination of eigenstates problem [closed]

Let's say that we have a system such that $$\Psi(x,0)=\frac{\sqrt3}{2}\phi_1(x)+\frac12\phi_2(x)$$ where both $\phi(x)$ are eigenfunctions of the Hamiltonian operator. I want to find $\Psi (x,t)$ ...
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### Why is a wave pulse a superposition of sine waves?

I have learned that to construct a wave pulse, we need to superimpose multiple sine waves of different frequencies which all interfere to produce the pulse. What I don't understand is that a wave ...
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### Extension of Schrödinger's cat thought experiment

My question is quite simple. In the thought experiment of Schroedinger's cat: When the scientist measures the state of the cat, its wavefunction collapses into either the alive or dead state. But ...
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### What happens if we measure the two entangled systems of the Bell test simultaneously?

Consider the Bell state $|\psi\rangle =\frac{|00\rangle +|11\rangle}{\sqrt{2}}$. When measuring one of the individual systems, the superposition is projected onto one of the eigenstates $|00\rangle$ ...
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### Standing waves due to two counter-propagating travelling waves of different amplitude

Suppose I have two counter-propagating travelling waves of the same frequency but of different amplitude, like the transverse waves produced in a string by partial reflection off an endpoint. I read ...
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### What does coherent superposition mean?

There is only one coherent state: $$|\alpha\rangle=e^{-\frac{|\alpha|^2}{2}}\sum_{n=0}^\infty \frac{\alpha^n}{\sqrt{n!}}|n\rangle$$ Also, a pure state does not mean a coherent state. But when does ...
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### Can a quantum mechanical system have more than one wave-function?

I was told that a quantum mechanical system is completely determined by its wave function. But superposition principle says that given two wave functions of some system, a linear combination of them ...
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### How to visualize an electron existing in two different places at the same time?

Let's consider a hypothetical situation where there are two electrons. The first electron is in superposition, simultaneously existing in two different locations. Let the locations be ...
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### Can coherent superpositions of a neutron and antineutron exist?

In my recent post I learned that electric charge is always conserved in contrast to strangeness quantum number, which limits the types of Hadrons that can be build. Furthermore, also different masses ...
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### Which arrangement of pipe and sources can create a standing wave?

A loudspeaker emitting sound of frequency f is placed at the open end of a pipe of length l which is closed at the other end. A standing wave is set up in the pipe. A series of pipes are then set up ...
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### Is superposition state of SHO ever observed? [closed]

Feynman says, "It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong." So, is superposition state of Simple ...
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### When two waves interfere, how to calculate the amplitude of the wave?

As the theory of superposition of waves express the amplitudes of the interfering waves do algebraically sum up. But when we sum up the the total energies of a particle doing a harmonic motion due to ...
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