# Questions tagged [superposition]

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 Schrödinger equation is linear) can be represented as a sum of two or more other distinct solutions, and so can be Fourier/eigenstate resolved to enhance mathematical tractability.

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### Finding the voltage across $R_3$ [closed]

I have the following circuit. $V_B = 18V, R_1=3k\Omega, R_2 = 6k\Omega, R_3 = 10k\Omega, R_4 = 1k\Omega \text{ and } I_A=1,2mA$. What's the value of $V_4$ here?
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### Superposition of waves and interference

For mechanical waves, Is the principle of superposition valid for waves that do not travel in the same plane ? For eg with one wave S1, travels along positive x-direction and another wave S2, is ...
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### Intensity In Superposition Of Waves

I'm not able to quite understand this: Consider a superposition of 2 opposite mechanical waves: when they interfere destructively, we say that the particles in the region of superposition have 0 ...
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### Schrödinger evolution after a position measurement, without collapse

Consider the following physical situation. Two position detectors are located next to each other, each one carries only YES/NO information on whether the particle hit that detector. A particle, let's ...
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1 vote
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### Gluons and their States

I've learned that gluons, which mediate strong interactions among quarks, always exist in a superposition of two or more color charges. To my knowledge, any superposition of eigenstates of an ...
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### Time dependent superposition [closed]

In the case of a particle in a infinite square well. The wavefunction is given by: $\sqrt{\frac{2}{L}} \sin{(\frac{n\pi}{L}x)}$ The probability is given by $|\psi(x)|^2$ Here the maximum value for ...
1 vote
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### Don't seem to understand the behaviour standing waves

I have many confusions regarding standing waves. Firstly, will the frequency of standing waves be the same as the emitted waves that make up the standing wave? What about wavelength? Will wavelength ...
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### Confused regarding the wavelength of standing waves and their relation with wave speed

Suppose we have an air column closed at one end and open at one end. We know, the general formula for the wavelength of the stationary waves of different harmonics will be equal to $4L/n$. My ...
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1 vote
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### How does dual nature of matter affect collision at the quantum level?

I have a question suppose having two fundamental particles collide which each other at the quantum scale , then what will the collision behave as Will the particle nature be dominant and make sure to ...
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### The evolution of observables in the Heisenberg picture

Suppose that a system $S$ undergoes the following time-evolution: $t_{1} \rightarrow t_{2}: |x_{a}\rangle \rightarrow \sum c_{i}|x_{i}\rangle$, where $|x_{a}\rangle$ and each of $|x_{i}\rangle$ is a ...
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1 vote
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### Is there any way to check superposition in a source of photons?

Suppose we are given a box containing 10 photons. We only know that the box contains: 5 horizontally and 5 vertically polarized photons or 5 left-circular and 5 right-circular polarized photons. ...
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### On the field leakage problem in quantum experiments

In a quantum experiment, does the leakage of the electromagnetic fields lead to the suppression of quantum effects? For example if I have an electron in a box, in some quantum superposition. Can I use ...
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### Visualizing 3D Lissajous curves

Lissajous figures are generally 2 dimensional, i.e. X and Y. But if an oscillation along a third axis Z (normal on the XY plane) is introduced, how would the resulting path look like? is there any ...
1 vote
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### Schrodinger's black hole [closed]

Is it possible to have an object that is a quantum superposition of a black hole and an equivalent mass that is not a black hole? Suppose we are adding iron atoms one at a time to a pile somewhere out ...
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### Erratum in Schlosshauer's "Decoherence" textbook (on the outcome of a SG experiment)?

In his textbook on Decoherence, Schlosshauer is trying to explicate the difference between a superposition and a classical ensemble. Considering a two-level system and using fairly standard notation, ...
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### What is the physical meaning of acting an operator on an arbitrary quantum state? [duplicate]

Let |+> and |-> are the two eigenstates of Pauli-X. If an incoming arbitrary state is |psi> = c1|+> + c2|-> and we act on this with pauli-X, then the outcoming state is a different ...
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### Superposition of charge states in the Neutral Pion

The quarks of neutral pions don't exist in a pure flavour state, and instead are described as a superposition of up-antiup with down-antidown: $\frac{u\bar{u}-d\bar{d}}{\sqrt{2}}$ However up and down ...
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1 vote
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### How much does the collapse of the wave function reveal about the state of the quantum prior to collapse?

The best way I can pose this question is through an example: suppose a photon passes through a beamsplitter, putting the photon into a superposition of the two paths (reflected or passed through), and ...
1 vote
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### Confusion with quantum superposition

I have been studying QM and I think doing research on quantum superposition got me more confused about the topic. So I have two interpretation that I came across: A quantum state that is in ...
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### Confusion about superposition of bound and scattering states in QM

My understanding is that bound states are solutions to the Schrodinger equation where $\lim_{x\to\pm\infty} V(x)=0$ and $\min V(x)\leq E \leq 0$, in which case there are discrete allowed energies. In ...
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### Question on notation of eigenvectors of position operator in quantum mechanics

From the first postulate of quantum mechanics we known that the vector $|\psi\rangle$ is the mathematical entity that says, intuitively, "in a time $t$, the (state of a) system is a vector". ...
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### ODE solutions for a driven oscillator in higher resonance modes

An ODE for a driven, undamped, oscillator might be written as $$m\frac{d^2y}{dt^2}+ky=\sin{(\sqrt{k/m})}t$$ If the initial conditions are $y(0)=0$ and $y'(0)=0$ and the values of parameters are $m=1$...
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### Feynman diagrams and path integral

In a Feynman diagram, can we consider that the propagator specifying the transition amplitude of a particle (let's say, of a "real" electron, or of a "virtual" photon) between two ...
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### Does a non-stationary quantum particle in a potential well approach a stationary solution of the Schrödinger Equation?

I have come across this video on Youtube where someone simulated the wave function of a moving particle in an unspecified harmonic potential well. (Link: https://www.youtube.com/watch?v=hHAxLE181sk , ...
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### Why does quantum superposition not cancel out the whole universe?

Sorry if this is a stupid question. My layman's understanding is that quantum mechanics describes the universe as a wave function, which can be understood as a weighted superposition (linear ...
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1 vote
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### Is all information of the quantum numbers $m\ell$ lost in a superposition?

I have learned that to create real spherical harmonics, a superposition of degenerate spherical harmonic eigenfunctions can be created using ±ml. For example, the px and py (l = 1) spherical harmonics ...
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### Is it correct to say that all nonstationary states in a superposition of nondegenerate eigenfunctions of the Hamiltonian? [closed]

Stationary states no not evolve with time, whereas nonstationary states do the opposite. I have essentially a two small questions (assume a time-independent Hamiltonian): Is it true to say that a ...
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### Is "high impedance" state analogy with "superposition" state? [closed]

In digital logic (classical bit), there's a state called "1" which is a defined high voltage, for example 2.7 V - 5.0 V. To achieve it we must connect it to VCC. And "0" which is a ...
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### A question on Faraday's law of electromagnetic induction

Faraday's law states that $$\varepsilon=-\frac{d{\phi}}{dt}$$ where $\phi$ is the magnetic flux and $\varepsilon$ is the induced emf. If the object is symmetric, it's easy to determine across which ...
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### Why, in low energy situations like atomic physics, are massive particles found to be in integer number states?

In quantum field theory electrons are conceptualized as quantized excitations of the quantum electron field. Generically the electron field can be in a superposition of number states. This is related ...
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### Does a waveform of frequency $f+\Delta f$ beat against a wave of frequency $2f$?

In the elementary treatment of waves, beating occurs between two waves of similar frequencies because $$\cos(2\pi f_1 t)+\cos(2\pi f_2 t) = 2\cos(2\pi \frac{f_1+f_2}{2}t)\cos(2\pi \frac{f_1-f_2}{2}t)$$...
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### Phase of the standing wave constituents

Do 2 superimposed waves have to be 180/0 degree apart to form a standing wave? It seems to be the necessity for forming nodes of 0 displacement (taken that their amplitudes are the same) but can they ...
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### How do different $|\text{Alive}\rangle+|\text{Dead}\rangle$ kind of states behave under decoherence?

I am looking for literature that investigates said behaviour for spins. So far I found many papers on how to measure the macroscopicity of states and therefore a classification of macroscopic states. ...
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