# Questions tagged [wavefunction]

A complex scalar field that describes a quantum mechanical system. The square of the modulus of the wave function gives the probability of the system to be found in a particular state. DO NOT USE THIS TAG for classical waves.

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### The matter wave concept, convergence in the macroscopic world and the contradiction

One of the postulates of quantum mechanics states that as the system of interest goes from the microscopic world to the macroscopic world, the quantum physical laws converge to classical physics. I ...
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### Full discription of wave behaviour of particles (e.g. electron diffraction) by wavefunctions

For example, according to the result of electron diffraction experiment, particles show wave characteristics. I also heard that according to Copenhagen interpretation and decoherence theory, before ...
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### Laughlin wave function and CFT

I have a question regarding Eq. (3.5) in Moore & Read's paper. They said \begin{equation} \Psi_{\text{Laughlin}}=\left\langle\prod_{i=1}^{N}e^{i\sqrt{q}\phi(z_i)}\exp\left[-i\int \mathrm d^2z^{\...
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### Contradictory statements on product states for distinguishable particles in Quantum Mechanics

Page no. $5$ in Many-Body Theory Exposed! by Willem H Dickhoff & Dimitri Van Neck states the following: The complex vector space, relevant for N particles, can be constructed as the direct ...
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### How to generalize outer product into its integral form assuming continuous basis?

(My current physics study is undergraduate quantum mechanics) By definition, the inner product is $w^Tu= \sum_i w_iu_i$, the outer product is $wu^T=w_iu_j$. According to Griffith, the inner product ...
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### Finite potential whose (normalisable) wavefunction doesn't vanish at infinity

I can come up with normalisable wavefunctions which don't vanish at infinity. However, I cannot come up with a potential so that it satisfies TDSE (the examples I think of are not differentiable at ...
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### Interpreting group velocity of free particle wave packet

I am trying to understand the concept of group velocity of a free particle wave packet: $$\Psi(x,t) = \frac{1}{\sqrt{2 \pi}}\int_{-\infty}^{\infty} \phi(k)e^{ikx}e^{-\frac{i \hbar k^2 t}{2m}}dk.$$ ...
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### Why do physicists, in quantum mechanics, call average an expectation value, not expected value? [closed]

I guess there is a specific reason for this - calling the expected observation $$\langle\psi|\hat{Q}|\psi\rangle$$ (for a normalised wavefunction) an expectation value. I heard somewhere that, in ...
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### Wheeler delayed choice experiment : why the mirror is not an interaction collapsing the wave?

I came across the Wheeler delayed choice as it is described in Wikipedia : To summerize, the individual photon has many paths and some path leads to detectors that reveals the path taken and some ...
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### Expectation value and the probability of finding a particle [closed]

I'm trying to understand basic quantum physics, as I understand, the expectation value of some random distribution gives us the outcome that we might expect(highest probability) if the event is done ...
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### Am I understanding the scattering amplitude correctly?

Suppose we have a particle, which is described by the wave function Ψ1, which hits another particle. In the final state, we get a superposition of an incident plane wave Ψ1 and a scattered spherical ...
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### Eigenvalue and Eigenfunction for a particle trapped in a 1D infinite asymmetric potential well [closed]

As we're barely scratching the surface of Quantum Physics in class, we haven't been taught about asymmetric potential wells. However, I find it fascinating, moreover difficult, to find the eigenvalues ...
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### Is the energy of the potential step quantized?

I'm solving the Schrödinger equation for a potential step and I was wondering if the energy of the potential step is quantized?
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### Something special about energy eigenstates when it comes to time evolution?

A particle is subject to an infinite square well potential with $$V(x)= \begin{cases} 0 & −a \lt x \lt a\\ \infty & \,\,\,\,\text{otherwise} \end{cases}$$ At a time $t=0$ its ...
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### The expectation value of momentum in an infinite well stationary state [duplicate]

For a particle in an infinite well potential given by: I am able to successful derive the normalized wavefunction as: $$u_n(x) =\sqrt{2/a}\sin(\frac{n\pi x}{a})$$ where this normalization has the ...
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### Why wave function does not vanish at a Dirac delta potential?

I have studied that a wave function should vanish at the location of an infinite potential. Consider a direct Delta delta potential at $x=0$. Why does does function not become zero here at $x=0$?
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### Normalize the variational wave function

I am trying to normalize the following variational wave function: $$\psi(x,\alpha)= |x|^{\alpha} + L^{\alpha}$$ and I'm using this: $$1= \int_{-L}^{L} |\psi(x,\alpha)|^2 dx$$ Solving the integral gave ...
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### Weird quantum linear operator [closed]

For a problem sheet at uni, I need to find eigenvalues and normalised eigenstates of a linear operator. This operator is $\hat{Q}$ and is defined by its action on the normalised eigenstates of the ...
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### What is the physical meaning of multiplication of two wavefunctions?

In the amount of quantum mechanics I'vs learnt I understand what wave functions are, how do we extract information from them and so on, and that addition of two wavefunctions on renormalization gives ...