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3
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2answers
77 views

What is the qualitative difference between quantum superpostion and mixed states? [duplicate]

As I understand it, if one has a complete knowledge of the state of a quantum system (insofar as one knows the statistical distributions of all the observables associated with the state) then one can ...
2
votes
1answer
42 views

Wavefunction Collapse

I believe my Lecturer and the textbook have contradicted one another. My lecturer gave the example that if the spatial part of the wavefunction of a particle is given by $\psi(x) = c_1\psi_1(x) + ...
0
votes
2answers
41 views

Why is a circuit of linear elements itself linear?

A resistor's voltage is proportional to it's current. V=iR. And a source maintains a constant voltage or current. So these are linear, time independent relations. If I put combinations of them in a ...
3
votes
1answer
55 views

Physiological Significance of Superposition

To what extent is the concept of superposition appropriate to physiology? In other words, can organisms "actually" exist in a state of superposition?
0
votes
1answer
37 views

How to find net wave formed by superposition of two waves with different amplitudes and different frequency? [closed]

The original question was: Choose true or false for each options. The equation of two sound waves are given by $$\begin{align} y_1 &= 3 \sin 100\pi t \\ y_2 &= 4 \sin 150\pi t ...
0
votes
2answers
53 views

What do operations on single Qubits of Unfactorable Superpositions Do?

So suppose I have the following Quantum Circuit: A ---- |Control| -----|Hadamard|---- B ---- |xxxxxxx|------------------------ Which is a 2 input Controlled Gate (applying some gate of two choices ...
4
votes
1answer
51 views

Non coherence of Fermions and Bosons through $U(1)$

I "know" the textbook answer why we cannot write, $$ |\psi\rangle = a|j=\tfrac{1}{2}\rangle + b|j=1\rangle $$ as "each term in the quantum superposition transforms differently under $U(1)$", $$ ...
1
vote
1answer
36 views

Failure of Superposition principle at high amplitudes

Why does superposition principle fail at high amplitudes. Please answer with respect to transverse waves. If possible, plane progressive transverse waves at best.
0
votes
1answer
45 views

Why does phase of a wave change after reflecting from a denser medium?

Why does phase of a wave change when reflected from a denser medium, but no change takes place in phase during transmission?
0
votes
2answers
56 views

Linear Combinations of Energy Eigenfunctions in 1D

Given that a particle is in a state defined by the wavefunction: $$\Psi (x,t) = \psi_0(x)e^{-iE_0t/\hbar}+\psi_1(x)e^{-iE_1t/\hbar}$$ where $\psi_0(x)$ and $\psi_1(x)$ are the energy eigenfunctions of ...
3
votes
1answer
47 views

Is QC with Superpositioned Quantum Gates any different than normal Quantum Computation?

This might be more appropriate for theoretical CS stackexchange, but it feels sufficiently low level to be relevant here. Consider the following thought experiment: I have a Quantum FPGA, it is a ...
0
votes
1answer
14 views

Working out the speed of a object by its frequency and a superposition wave?

Say you have 2 loudspeakers facing each other and they are separated by 20m, but are connected to the same oscillator and so both have a signal frequency of 800Hz. I calculated the separation of the ...
2
votes
2answers
64 views

How can 2 EM waves null each other at a point but continue to propagate?

how can 2 EM waves (travelling in opposite directions) null each other at a point in space but continue to propagate beyond the point in space where they interact to null each other?
64
votes
3answers
3k views

Why do travelling waves continue after amplitude sum = 0?

My professor asked an interesting question at the end of the last class, but I can't figure out the answer. The question is this (recalled from memory): There are two travelling wave pulses moving in ...
1
vote
1answer
71 views

Difference between phase space and Hilbert space? [closed]

Why is the phase space of classical mechanics not a vector space, but Hilbert space of QM is?
1
vote
4answers
175 views

The Theoretical Minimum: Confusion Over Susskind's Reasoning for mutually orthogonal states

There's a better title for this question but my brain is so fried I can't come up with one. Important Note: I am a layman, and my understanding of the mathematical concepts of quantum mechanics is ...
4
votes
1answer
87 views

When does the principle of superposition apply?

I assumed from my general physics courses that the principle of superposition was just an empirical fact about forces. Then I could understand that derived quantities like the $E$ and $B$ fields ...
0
votes
0answers
49 views

Classical wave equation - validity

I know that classical wave equation carries for spherical wave fronts. In addition, Huygens' principle states that any wave front is a superposition of many spherical wavelets, so why does the ...
2
votes
2answers
79 views

Can gravity prevent quantum superposition of positions for a massive object?

Theoretically, nothing prevents a really massive object to be in a superposition of two spatial locations, even far away one from the other. Then I guess spacetime would also show the superposition of ...
0
votes
1answer
58 views

Why superposition is useful just for linear functions?

I saw a problem which said that we have a bar between two walls and we increase the temperature. and as you know walls push a force to the bar so the length of it does not change. in the solution I ...
0
votes
1answer
81 views

Relationship between Quantum superposition and Uncertainty principle

I'm an amateur in quantum mechanics. I am confused after reading the following in the wikipedia article about quantum superposition: If the operators corresponding to two observables do not ...
0
votes
1answer
33 views

Using superposition to find current

I'm given the following problem I'm a little bit confused about superposition problems when current flows through a voltage source but not the resistor. 1) When I looked at the solution for this ...
1
vote
1answer
49 views

Understanding amplitude amplification in quantum computing

In short, what is the essence of amplitude amplification type of techniques that appear in quantum computing? More precisely, my main questions are, relating them more to Grover's search which ...
0
votes
3answers
60 views

Is the sum of two stationary states of different energies also a stationary state?

The question title kind of speaks for itself really. I was thinking of maybe using the orthogonality relation to try to show this: $$\int_{-\infty}^{\infty}\phi_n(x)\phi_m(x)dx=\delta_{nm}.$$ ...
0
votes
1answer
38 views

How do we acquire c-coefficients (“weights”, “probabilities”), when dealing with superposition of stationary states? [closed]

I searched quite a lot textbooks to answer this question, but I couldn't find anything satisfactory. This could be more general question, but it will be easier to just restrain to particle (say ...
-2
votes
1answer
95 views

Why is particle superposition still part of quantum mechanics? [duplicate]

After reading an article on Schrodinger's Cat, it seems that if we take the environment as an observer, that superposition cannot occur because all atomic and subatomic entities would be observed all ...
2
votes
1answer
89 views

Why do we hear the square of the wave?

Assume we superpose two waves of frequencies $\omega_1, \omega_2$. Then what we get are beats. Adding the two sines gives us $$\psi = A\sin(\omega_1 t) + A\sin(\omega_2 t) = 2 \sin ...
1
vote
1answer
37 views

Re-entering superposition

I've realized that I'm somewhat familiar with what happens when an system in a superposition is "measured". But not at all with what happens after. Example: If there is an electron in a ...
2
votes
1answer
79 views

How to calculate the frequency of oscillation of superposition states [closed]

Been working on this question for a while and I'm not sure how to go about it. Could someone point me in the right direction, particularly for the frequency question. The question is as follows: A ...
2
votes
1answer
75 views

Entanglement, superposition, and propositional logic [duplicate]

From what I am understanding, there is entanglement in a system if there is a correlation between elements of that system. For an example that I found, If you have only two cards and know that one is ...
2
votes
1answer
155 views

Hydrogen atom in superposition of energy eigenstates

Suppose a single hydrogen atom is in a superposition of energy eigenstates: $$ \psi = \frac{1}{\sqrt{2}}\psi_{100} + \frac{1}{\sqrt{2}}\psi_{200} \,.$$ Then energy will be $E = ...
0
votes
1answer
66 views

Current quantum theory of interference

I have always thought that the quantum theory states that interference occurs when photons behave like waves and two or more possible paths exist. Interference can then be destroyed if the path of the ...
0
votes
1answer
100 views

What exactly is Schrodinger's Cat? [closed]

What exactly is Schrodinger's Cat? The little bit reading I did led me to believe that he wanted to assert the cat is dead OR alive only if you observe. What does it signify? How did it affect the way ...
0
votes
0answers
45 views

Proving law of reflection using Huygens principle

So I was reading the proof of law of reflection using Huygens principle but as I am new on this website so I can't attach a picture,so I will try to explain by writing only. The problem I face is ...
1
vote
1answer
33 views

QCD-Process with superposition-particle

I am a total beginner with non-abelian gauges. To write down a process from a neutral pion ($\pi^0 = \frac{1}{\sqrt{2}}(u\overline{u}-d\overline{d})$) I expect to have to write it as this ...
3
votes
1answer
79 views

Superposition State in Coin Toss

I was reading the following lines from Quantum Computation and Quantum Information by Nielsen and Chuang on page 278 of chapter 7. A coin has two states and makes a good bit but a poor qubit ...
2
votes
1answer
94 views

Electric field of a Uniformly charged sphere with a cavity [closed]

I have the following question: Consider a sphere of radius $R$, uniformly charged with a volume density $\rho$. The sphere has a spherical hole of radius $R/4$ at a distance $R/2$ from the ...
1
vote
1answer
75 views

Physical interpretation of the constant coefficient appearing in solution to the Schrodinger equation

The product solution to the Schrodinger's equation is $$\Psi_{n} \left ( x,t \right )=\psi\left ( x \right )\phi\left ( t \right )$$ By superposition, the solution becomes $$\Psi \left ( x,t ...
1
vote
0answers
34 views

Superposition of discrete level and continuum: Electron bound and free [duplicate]

Superposition between discrete states of a system is widely considered in the literature, but this system, e.g., a $H$ atom, can also have a continuum in its energy spectrum. Can the state of a ...
0
votes
1answer
219 views

Combination of Simple Harmonic Motions

Will the combination of 2 Simple Harmonic motions will be an SHM in itself? For example for simple functions such as $$\ f(t)=\sin\omega t-\cos\omega t$$ I can use trigonometry to show that it can ...
1
vote
2answers
167 views

How can the central maximum in a double slit experiment have greater intensity than the original beam?

I have read in more than one place that the maximum intensity in a double slit experiment can be defined as the sum of the amplitudes of the light in each slit. For example, if the intensity of a ...
11
votes
3answers
2k views

Quantum Joke (not a real joke, not a riddle)

Supposing I want to make a quantum joke, like writing this on a coffee machine: $$| \text{Status}\rangle = \frac{1}{\sqrt{2}}\ \big( | \text{Working}\rangle \color{red}{\pm} | \text{Down}\rangle ...
0
votes
0answers
40 views

Classical string as a limit case of elastic quantum states superposition

The usuall way to "half-popularly" show that the quantum mechanics formalism is not unconnected to the classical mechanics is to demonstrate a classical case as a limit of a quantum case. The main ...
4
votes
5answers
182 views

Looking for clarification on superposition [closed]

I have always had a hard time accepting the concept of superposition from quantum mechanics. I know that the leading physicists say that the cat is both alive and dead until it is observed and that an ...
1
vote
1answer
58 views

Kim delayed choice experiment

In Kim's delayed choice experiment as described in Wikipedia, you get interference patterns or not depending on whether you look at detectors D3 and D4 (which give you path information) or look at ...
2
votes
2answers
74 views

Measurement on a particle described by a quantum superposition of quark states

Some particles are described as a quantum superposition of quark states. For example, the pion meson: $$ |\pi^0⟩=\frac{|u\bar u⟩−|d \bar d⟩}{\sqrt{2}} $$ Is it possible to design an experiment giving ...
3
votes
3answers
664 views

A quantum particle moving from A to B will take every possible path from A to B at the same time

If a quantum particle can take an unlimited number of paths to get from point A to point B wouldn't a quantum particle never get from point A to point B? A quantum particle takes every path at the ...
1
vote
2answers
126 views

Does this quote from my textbook imply that not all states are superpositions?

I read this at a book; The difference between bits and qubits is that a qubit can be in a state other than $|0\rangle$ or $|1\rangle$. It is also possible to form linear combinations of ...
1
vote
2answers
328 views

Problem in understanding the concept of 'superposition' as explained by Dirac

The concept of 'superposition' has really made me insane, actually. What I thought it was just simple superposition of matter waves. For instance, let's take the Double-Slit experiment: take the ...
0
votes
3answers
374 views

Is the superposition of stationary states a stationary state? If not, then why not?

I am a beginner in Quantum mechanics and as I understand,the superposition of stationary states is also a solution of time-independent Schrödinger equation (TISE). The wave functions that are the ...