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# 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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84 views

### Double slit experiment- light intensity

The standard explanation for the interference pattern is one of constructive and destructive interference between the light waves from the two slits. But, am I right in thinking that light intensity ...
118 views

### Interference of Schrödinger's Cat states?

A "Schrödinger's cat state" is a macroscopic superposition state. Quantum states can interfere in simple experiments (such as the Mach-Zehnder/Hong-Ou Mandel/etc). Can Schrödinger's cat states be made ...
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### Does the non-linear Schrodinger equation satisfy quantum mechanics rules?

Thinking about the 0+1 dimensional (time-only) non-linear Schrodinger equation: $$i\frac{\partial}{\partial t} \psi(t) =\kappa |\psi(t)|^2 \psi(t).$$ Treating $\psi$ as a wave function instead of a ...
266 views

### Constructive interference derivation

What is the difference between using $y=A\sin\omega t$ and $y=A\sin(ct-x)$ in a wave formula? I am not a math student and I am not getting this.
172 views

### The superposition principle for linear waves

As far as i've seen, the proof for that principle is to show that, the equation representing linear waves has the perk of being linear, thus if y(x,t) and z(x,t) are solutions of the linear equation,...
173 views

### Principle of interference between two waves of same wavelength

We have two waves with the same wavelength that have a path difference. Why does the path length difference have to be an integer multiple of the wavelength in order to obtain constructive ...
73 views

### How can you know an unmeasured quantum particle is in several states at once?

If a quantum particle/system has not been measured/observed yet, how can you know it is in several places/states at the same time?
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### Does it make sense to ask: what is the probability of a particle being found in a certain state at time $t>0$?

I am dealing with a problem which involves a quantum system of orthonormal two states, $\left|\nu_1\right>$ and $\left|\nu_2\right>$, which are eigenstates of a time-independent Hamiltonian, ...
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### Can two semi-infinite plane waves undergo perfectly constructive interference?

This is building off of a question I asked here. When discussing the linked problem with some friends, the consensus seemed to be that the reason two identical semi-infinite plane waves cannot ...
72 views

### Three slits experiments [closed]

What is the results of three slits experiments ? What is the difference between it and 2 slits experiments?? How can measure superposition by three slits experiments
3k views

### If I was Schrödinger's cat, what would I feel? [closed]

What I'm doing Note before reading: I've made two edits for clarification The first starts at: "To clarify based on answers, I think ya'll are missing the meat of the question:" The second starts ...
150 views

### Time evolution of eigenstates superposition

If a system is in a state $\psi$ which is superposition of, let's say two, energy eigenfunction, namely $\psi_1$ and $\psi_2$, so that $$\psi(t)=\psi_1e^{-i\omega_1t}+\psi_2e^{-i\omega_2t}$$ (I am ...
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### Polarization of light using QM principles [duplicate]

If we have vertical linearly polarized light and if we put it through a polarizing filter oriented at 45 to the vertical, then only half of the light passes through. I am able to intuitively grasp ...
45 views

### Can light of different frequencies interfere with each other?

In principle I'm aware of superposition and how it works. Nevertheless I'm not really able to answer the following: Will two light beams of different frequencies interfere with each other? More ...
105 views

### Would Schroedinger's cat smell 50% like death? [duplicate]

If we left Schroedinger's cat in a superposition for a week would it begin to start smelling 50% like a dead cat and 50% like a living cat? Would the smell of death immediately disappear if we opened ...
119 views

### Quantum superposition in density matrix formalism

I was thinking about quantum superposition and stumbled into something that made me quite uncomfortable. Consider a qubit with Hamiltonian eigenstates $|0\rangle$ and $|1\rangle$. To each of these ...
161 views

### Superposition principle in electrostatics

Poisson's equation in electrostatic does not satisfy the linear superposition principle. Can I say that since Laplacian operator is a non-linear operator so it does not follow the linear superposition ...
191 views

### What happens in an organ pipe at frequencies other than the harmonics?

I learned that, at frequencies corresponding to harmonics, standing waves are formed. But what actually happens at other frequencies? Won't the reflected wave superimpose with the original wave? Do ...
77 views

### Destructive Interference of two wave pulses [duplicate]

Suppose two identical transverse wave pulses are travelling towards each other on a string where one is inverted with respect to the other. When they meet, destructive interference will occur and the ...
101 views

### On Superposition In Diffraction

I am a high school student learning Physics. I am currently learning about diffraction of waves, be it water waves, light waves each, in systems where there are 2 slits for it to diffract through. I ...
172 views

### Solution of Schrodinger equation

I am reading 'Particle in 1 dimensional box' and 'Potential step' in Quantum Mechanics. In the figure shown we have two same looking schrodinger equations, equation 1 and equation 2. Why solutions of ...
214 views

### Linear combination of wavefunction

What does plus or minus sign indicate in linear combination of wave functions?
267 views

### How to interpret a wavepacket in quantum field theory: is it one particle or a superposition of many?

In 'classical' quantum mechanics, a wave packet is a (more or less) localized particle. The wave packet can be expanded in a superposition of plane waves, each with a defined momentum and energy. This ...
132 views

### Which-way experiment with electrons

Consider the double-slit experiment done with a stream of electrons, sent individually toward the double-slit screen and detection plate. A moving electron is a moving electric charge, which by ...
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### De Broglie Wavelength interpretation

I've just started learning about the double slit experiment (just in the short appendix section in Schroeder's Thermal Physics), and I'm extremely confused by this one thing: In it, out of basically ...
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### How to conduct the electron double slit experiment

I am planning to conduct the electron double slit experiment for a project in my school. Even after researching quite a bit online, I wasn't able to find a proper guide that explains the materials and ...
160 views

### Can a superposition of a travelling wave and a standing wave give a standing wave?

I have two similar questions: 1) I have heard, that a travelling wave can be understood as a superposition of standing waves. Can you exaplain this (some images would be wonderful)? 2) Can a ...
82 views

### Never ending quantum superposition? [closed]

So I am wondering over the Copenhagen Interpretation how can a decoherence or measurement ever happen. If in the beginning of the universe everything was in a state of coherence being in ...
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### Supposing that a quantum system is in a degenerate ground-state, is it valid to call this a “superposition” of the possible groundstates?

According to the adiabatic theorem, a quantum system can be prepared in the ground-state of some Hamiltonian $H_f$ if it starts in the ground state of some Hamiltonian $H_I$ and is varied "slowly" ...
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### Direction of wave propagation unchanged after superposition?

It's quite confusing.Principle of superposition states that the amplitude of two superposing wave eqauls their indivisual amplitude vector sum.But what about direction.Souldnt't wave direction of ...
275 views

### Why is electrostatic force a function of the product of charges, not the sum?

When you have two forces , you ADD them to get the total. If both of us push on a car, the total force on the car is the sum of our forces. But, If we have an electron approaching another electron, ...
177 views

### Linear and non-linear systems

When I read about the superposition principle, it says that it works only on linear systems, my problem is that I cannot really understand the difference between a linear and a non-linear system. I ...
101 views

### Rules of addition of electric field

According to the principle of superposition of Electric Fields , we know that Electric fields add using laws of vectors. However while adding the electric fields , if for example one field is ...
161 views

### Is this assertion by Landau and Lifshitz's QM equivalent to the axiom that state spaces are vector spaces?

Many expositions of Quantum Mechanics begin by stating axioms of the following type: "The state of a quantum mechanical system is given by a nonzero vector in a complex vector (or Hilbert space) ...
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### Double-Slit experiment and the role of observation in the distribution

so I am still having difficulty understanding the role of measuring/observing the wave function. Many of the videos I have watched says that when we are not looking at the wave function it makes an ...