Superposition Definition and 673 Threads

What is the "superposition principle"? I have a confusion about one of the fundamental concepts of quantum mechanics, the principle of superposition This sounds, more or less: a linear combination with arbitrary coefficients of different quantum states is a new quantum state If I have (for...

My question is, "Is superposition necessarily and only related to the time between triggering and observation?" And further on that point, in the MWI theory, as opposed to the Copenhagen interpretation, do quantum particles actually enter and "exist" in a superposed realm before observation? Or...

Homework Statement y1(x,t) = 5.00sin(2.00x - 10.0t) y2(x,t) = 10.0cos(2.00x - 10.0t) a) Prove that the wave that is the result of the superposition is a function of sin. b) What's the phase angle and amplitude of said wave? Homework Equations y = y1 + y2 The Attempt at a Solution...

I suspect the following reasoning is faulty, but I am not sure why. Hence I would appreciate someone pointing out the errors. That is, which, if any, of the following statements are incorrect, and why? 1) Theoretically, albeit not practically due to the large numbers involved, the laws of...

Is anyone aware of a concise review of the experimental evidence of the nature of the gravitational field due to an entity in spatial superposition? Is it known (or generally presumed) that photons exert gravitational attraction through the stress-energy tensor at all points in space related to...

When measured/viewed particles in superposition collapse and take the form of one state. So how do we know they are in superposition in the first place. And do we know why they collapse into one state?

Imagine two electromagnetic waves are traveling in opposing directions such that they eventually meet, overlap, and continue traveling as usual after the superposition/overlapping event. Just before they overlap there is some superposition effect taking place but not enough to fully merge the...

It is said that no Hermitian operator gives a time evolution where "I observed the spin to be both up and down" is a possible result. If you use non-Hermitian operator.. then it's possible.. and what operator is that where it is possible in principle where "I observed the spin to be both up and...

Say you flip a coin and place your hand above it before you view it. Now the coin is in a super position where it's both heads and tails. Once you look at it, you'll know what side is up and the wave function collapse. Say you are flipping two coins instead. The odds of both being heads is 25%...

In another thread, that is now closed, someone said that 1000's of experiments support the proposition that a particle can be in two, mutually exclusive states at the same time. The results of experiments show just the opposite. The measured result is not a superposition state. They never...

Pages 20 and 21 of this article, http://www.quantum.umb.edu/Jacobs/QMT/QMT_Chapter1.pdf, appear to prove that electrons in the double slit experiment must be thought of as actually being in the superposition of two states at the same time. He uses the interference term in the probability...

Would there be destructive interference if I had two waves that are superimposed and the peak of one wave met the trough of the other but they both have different amplitudes? If there isn't total destructive interference, then what does the final wave look like?

Can someone please explain what's going on at 47:40 Thanks in advance.

I don't get the first part. why did he make the angle of sin equal to n pi.

The way I am coming to understand it, the allowed states that an observable can be "observed/measured" in are defined by the eigenvectors (and associated eigenvalues) of the observable's operator. Since those eigenvectors form a basis and span the space of vectors defined by the operator, a...

This ought to be some simple gap in my knowledge, but it bugs me nonetheless. Let me present the argument as I see it, I'm fairly certain that there is just some tiny part that I didn't learn correctly. Let us assume a wavefunction $$\Psi$$ is defined as a superposition of two wavefunctions...

Has anyone considered the possibility that the passing of time is simply the rate of observation of particles collapsing from superposition? And once collapsed, then this is what we understand as the Past, while those still in a probabilistic state is what we understand as the Future?

It's well known that a single particle can exist in superposition, but what about the gravity of the particle? Is the gravity also in superposition? I suppose this makes it difficult to write a wavefunction, since we can't express it in terms of a field over a single spacetime. But what if we...

[Mentor's note: Split off from this thread] I hope I am not hijacking this thread, but I noticed something. When a system is in a superposition of quantum states, as in the six atoms example, isn't that an expression that, from the probability viewpoint, they do not know what state it is in...

Homework Statement Hi, I was wondering if anybody has an idea how to divide the forces on this structure to get the dispacement of the node 4. 2. Formulas I would like to solve this task by superpositioning forces working on different elements of the construction. (note different EI) using...

Hello, sorry, I do realize that this question has been asked before but there are just a few things I would like to figure out. So, in my mind the differences lie in knowing the states that the system could end up in, and also the difference in the probabilities. Is this thinking correct...

Is it in a Quantum superposition, and then only in a mixed state when finding the reduced state of a qubit from an entanglement of multiple qubits?

Hello, just a quick question. I am aware that a a state in a space can be written as a linear combination of the basis kets of that space ψ = ∑ai[ψi] where ai are coefficients and [ψi] are the basis vectors. I was just wondering is this a linear superposition of states or just a linear...

Homework Statement Two waves are produced simultaneously on a string of length L = 1 m. One wave has a wavelength λ of 0.5 m. The other wave has a wavelength λ of 0.2 m. The amplitudes of the waves are the same. At t=0, at what locations x0 is the displacement y(x0) equal to zero? At what...

Hi all, I'm a computer scientist who has been getting an increasing fascination with quantum physics. I admit I am a novice in this respect. I had a question just for my own learning and understanding, not related to a class or anything like that. :) In learning more about superposition and...

I am wondering is someone could comment on a question I have recently answered. I have attached the question and my answer. Apologies for not following the standard procedure of Latex but there are drawings associated with this question. I answered section A and my results are written on the...

Does a superposed state of an electron exist over a larger amount of space than the state of an electron as a particle?

According to Sabine http://backreaction.blogspot.com/2016/03/dear-dr-b-what-is-difference-between.html you can make superposition go away by just changing the basis state.. "All this is just to say that whether a particle is or isn’t in a superposition is ambiguous. You can always make its...

Homework Statement Find the expression for the electric field at point M(a,a,0) if the linear charge density is known ( ##Q'## ) Homework Equations 3. The Attempt at a Solution [/B] I tried something like this and would like your feedback on it. I separated the triangle into three parts...

Homework Statement Using the superposition principle, determine the current i(t. 2. Homework Equations Zc = 1/jwC Zl = jwL V = I*R I = V/Z The Attempt at a Solution First, I converted inductor/capacitor to impedance: L = 1.5H -> jwL = j * 10 * 1.5 = 15j C = 10mf = 1/(jwC) =...

Are quantum superposition, Heisenberg uncertainty principle, wave/particle duality the same thing? Do they imply each other? They all seem the same to me like the wave-like nature of photons -> superposition, and superposition means there's not definite position -> uncertainty principle. Sorry...

As I understand Coulomb potential associated with charged particle is described classically. My question is if there is a way how to describe Coulomb potential of charged particle that is in quantum superposition of being "here" and "there"? My motivation for question is that I am trying to...

I apologize if this question seems like gibberish, Its been annoying me. I tried to ask this once but i didnt ask it properly. If there was a complex structure of sub atomic particles, and each sub atomic particle was in its individual space time vector, or eigenstate, and they where each...

For properly normalized extensive macroscopic properties (and this includes the center of mass operator), there is such a proof in many treatises of statistical mechanics. It is the quantum analogue of the system size expansion for classical stochastic processes. For example, see Theorem 9.3.3...

First let me ask this: Consider a pair of entangled photons fired at a respective detector after passing respective polarisation filters. If a photon passes a polarisation filter, is it in a superposition of having passed and not having passed? Is the measuring device (that detects the...

While studying the wiki article for Quantum Superposition, I find this sentence: “An example of a physically observable manifestation of superposition is interference peaks from an electron wave in a double-slit experiment.” Can someone explain how interference proves (shows? demonstrates?)...

Hi. I have read many times that the Schrodinger equation is a linear equation and so if Ψ1 and Ψ2 are both solutions to the equation then so is Ψ1 + Ψ2. Is this use of the word linear the same as generally used for differential equations ? As the Schrodinger equation is also an eigenvalue...

I've seen a couple of lectures by Penrose where he describes an experiment to test superposition of physical location of a very small, but macroscopic object. I can't find a reference to it online, but the experiment involved sending a photon through a half-mirror, and depending on the route...

This relates to a homework question which I have spent considerable time on and although I understand the concepts, the process of getting to the answer is difficult because of several different 'versions' of the right answer I see. The relevant threads are...

I was watching a MIT opencourseware video on quantum mechanics. The first video is on superposition. The link is here: http://ocw.mit.edu/courses/physics/8-04-quantum-physics-i-spring-2013/lecture-videos/lecture-1/ In short the lecture shows a series of experiments done on electron spin in the...

I am confused about pure state or in mixed states. I've seen several threads on this forum, but I still can't get the grasp of it. I only have very little quantum chemistry to know what these means. So instead, I want to know the answer for specific examples so that I can get an idea. So I...

Hello everyone. I've gotten interested in quantum mechanics after binge watching a ton of documentaries about it. I've grown particularly interested in superpositions and the measurement problem. I'm not very good at math, so I can't understand the math behind it, but I like to take the...

I googled a bit about this and managed to find this http://arxiv.org/abs/quant-ph/0505056 http://physics.bu.edu/~mohanty/physica-decoherence.pdf Since I can't make much out of them, maybe except this interesting phrase in the first one "First of all it is intriguing that even at absolute zero...

Hi all, I asked for help with one part of this question here. But after thinking about another part of the question, I realized I didn't understand it as well as I'd thought. Homework Statement Ψ(x,0)=A(iexp(ikx)+2exp(−ikx)) is a wave function. A is a constant. Can Ψ be normalised? Homework...

Homework Statement Exercise 4.15 on the image. The exercise asks for the value of the current I using superposition Homework Equations Superposition theorem, nodal and mesh analysis The Attempt at a Solution I think i am doing the mesh analysis wrong, but can't see where. Can someone...

Homework Statement The problemas statement is: "Find Vo and Io by the superposition principle" Homework Equations Nodal Analysis and The Superposition Theorem. The Attempt at a Solution So, I tried to shutdown first the independent 30V tension font. It led me to Vo = 8V. Then, turning off...

I decided to perform a little thought experiment -- without the mathematics. Assume we have two Schrodingers' Cats. After a while, they will be in a superposition of being alive and dead at the same time. Now assume that they are entangled, and we open the boxes at the exact same time. Cases...

Hi, I can't quite understand how to do this question please could someone help :) Show, by the principle of superposition, that u(x, t) = ∞ ∑ An sin(npix)e2n2pi2t n=1 where A1, A2,..., are arbitrary constants. Thanks

I understand that if we have a quantum mechanical system, then its state at some given time ##t## is fully described by a state vector ##\lvert\psi(t)\rangle## in a corresponding Hilbert space. This state vector containing all possible information about the distributions (of all possible values)...

One of my students asked me the seemingly innocuous question of "how does wind affect the speed of sound?". My immediate thought was that the velocity of the wave would be the vector sum of the velocity of the wind and the velocity of sound waves in still air. However, upon further reflection I...