Quantum and general physics Definition and 151 Threads

Hi, Can someone please explain as to why light beams attract or repel each other even when they don't have charge. Seems like it behaves like two current carrying parallel wires. There is very little material about this which goes completely above the head. Thanks

Homework Statement At ##t = 0##, a particle of mass m in the harmonic oscillator potential, ##V(x) = \frac1 2 mw^2x^2## has the wave function:$$\psi(x,0)=A(1-2\sqrt\frac{mw} {\hbar} x)^2e^{\frac{-mw}{2\hbar}x^2}$$ where A is a constant If we make a measurement of the energy, what possible...

Hello. I am a new member of this forum. My name's Patrick and I'm 1st year Wrocław University of Science and Technology student. I decided to study, as in title, quantuum engineering, because I think, saying succinctly, everything in the future will be based on quantuum technology - AIs, nanobot...

Hello all, I have recently graduated with a BSc in physics and have been accepted into the MSc program for Applied Physics. However, due to the job outlook for the position I actually want to do I am deeply interested in pursuing my second interest, which is, AI. Question: My main question is...

Homework Statement The maximum no of spectral lines for a single atom during it's electron's transition is given by [∆n(∆n+1)]/2 . But I don't seem to arrive at the answer when a group of atoms are present . The question was - What is the maximum number of spectral lines possible for Balmer...

Hi, I am looking for textbooks in QFT. I studied QFT using Peskin And Schroeder + two year master's degree QFT programme. I want to know about the next items: 1) Lorentz group and Lie group (precise adjectives, group representation and connection between fields and spins from the standpoint of...

Hi, does treating neutrons as waves make any difference when it comes to micro cross sections ? , does quantum mechanics help more than classical mechanics in nuclear reactor physics ? Noticing that I am a nuclear engineering student

Are quantum harmonic oscillators, vacuum fluctuations and radiation modes the same? Is vacuum energy caused by vacuum quantum fluctuations?

Hi guys! I'm a high school student and I love Physics. I hope this site will help me learn and understand a lot of (new) things! :)

Hi, I've just gotten started with basic quantum physics in physics class and we've just talked about ionization energy. It is stated that the energy of a hydrogen atom is -13.60eV (or -2.179aJ). I assume this is the potential energy (and that this is the reason the atom has a lower mass than the...

I am going through my Quantum textbook, just reviewing the material, i.e. this isn't a homework question. We are solving the radial equation for the Hydrogen Atom, first looking at the asymptotic behavior. My issue is I am completely blanking on how to solve the differential equation...

I am trying to numerically integrate the following complicated expression: $$\frac{-2\exp{\frac{-4m(u^2+v^2+vw+w^2+u(v+w))}{\hbar^2\beta}-\frac{\hbar\beta(16\epsilon^2-8m\epsilon(-uv+uw+vw+w^2-4(u+w)\xi...

There is an operator in a three-state system given by: 2 0 0 A_hat = 0 0 i 0 -i 0 a) Find the eigenvalues and Eigenvectors of the operator b) Find the Matrix elements of A_hat in the basis of the eigenvectors of B_hat c) Find the Matrix Elements of A_hat...

Homework Statement Consider an experiment on a system that can be described using two basis functions. We begin in the ground state of a Hamiltonian H0 at a time t1, then rapidly change the hamiltonian to H1 at the time t1. At a later time tD>t1 you preform a measurement of an observable D...

How can we harness that energy? Is there any engine, heater, battery or other thing that uses it?

It is usually referred to as Phonons for sound waves in solid. But, where it gets confusing, is in gases and air. Some still call it Phonons, others say, Phonons can only be used in solid states. So what is the Quantum of Sound in Gases/Air? And if possible, refer to any text which speaks of...

I have to calculate the Expectation Value of an Energy Eigenstate : < En > The integral is ∫ ψ* En ψ dx I have : A ) ψ = √L/2 sin nπx/L , a single standing wave of the wave function B ) ψ = BsinBcosD , the wave function of the particle C ) ψ = ΣCn ψn = C , sum of all the...

Homework Statement A simplified E versus k curve for an electron in the conduction band is given. the value of a is 10 Å. Determine the relative effective mass m* / m0. Homework Equations [/B] m* = ħ2 / (d2E /dk2) m0 = 9.11 E-31kg 3. The Attempt at a Solution The second derivative must...

Hello, here there are 2 things (one about hologramic universe and the other about a quantum physics test similar to the slit lamp. The first one is about the Bohm and Pibram as well as one about Alain Aspect 1982 study: articles about their theories...

Suppose instead of moving at the speed of light , someone moves at a speed of 2*10^8 m/s .Then will his mas and energy exist simultaneously ? I mean mostly energy and some mass ?

I am reading Cohen-Tannoudji's Atom photon interactions (2004 version), in the Appendix he explains that for atom-light interaction, the electric dipole Hamiltonian (d.E form) is got from the original, "physical" (in line with his language) p.A form Hamiltonian by a time-independent unitary...

What exactly does class of time correlation functions measure of particle in quantum mechanics? In particular, I would love to know the answer in the context of Kubo-transform time correlation function.

Hey everyone, I've been doing some quantum mechanics but I think I have yet to fully grasp the meaning of eigenstate. What I mean is, I understand that an eigenstate ##x## is such that, if we have an operator ##\hat{A}##, it satisfies ##\hat{A} x=\lambda x## and so ##\hat{A}## represents a...

Greetings everyone! I have been trained as a mechanical engineer, but I retain a strong interest in quantum theory and read what I can. In case you didn't know, my handle is a reference to Richard Feynman's comment on angular momentum from The Feynman Lectures on Physics. I look forward to...

Good day, I try to differentiate GHZ-state and W-state using three tangle. Suppose The value three tangle for GHZ-state equal to 1 while W-state equal to 0. I used three tangle formula, $$\tau_{ABC}=\tau_{A(BC)}-\tau_{AB}-\tau_{AC}=2(\lambda^{AB}.\lambda^{AB}+\lambda^{AC}.\lambda^{AC})$$...

Good day, May anyone help me to confirm the formula use for three tangle using concurrence. From my reading, three tangle, $$\tau=\tau_{A(BC)}-\tau_{AB}-\tau_{AC}$$ and it can be related to concurrence $$\tau=C^2_{A(BC)}-C^2_{AB}-C^2_{AC}$$ and I used formula for C is...

According to observations and known models mass is equal to the amount of atoms in a given space, and gravity is proportional to the amount of mass in a given space (ie. Sun > Earth > Moon) If those observations are undeniable then my question remains: is gravity directly related to groupings of...

From my reading, the X between SU(4)XSU(2) mean Cartesian product. But How the way to mutiply two matrix A in SU(4) and B in SU(2). Example the matrix A=\begin{pmatrix} a & b & c & d \\ e& f & g & h \\ i & j & k & l \\ m & n& o & p \end{pmatrix} and B=\begin{pmatrix} 1 &2 \\ 3 &4...

<< Mentor Note -- thread moved from Homework Help forums to General Math >> Good day, I run coding in Mathematica. But, I get singular matrix A at certain loop. In theory, how can I make matrix A become orthogonal A=\begin{pmatrix} 0& 0 & 0 & 0 & 0 & 0 & 0 & 0\\ 0& 0 & 0 & 0 & 0 & 0 & 0 &...

Have any experiments on the Casimir effect tried what happens if the plates are temporarily magnetized when they are pulled together by the effect? E.g. measurements of what happens to passing laser beams and the like?

Given the equation ##\frac{d^2 \psi (x)}{{dt}^2}+\frac{2m}{{\hbar}^2}(E-V(x))=0## the general solution is: $$\psi (x)=A_1 e^{ix \sqrt{\frac{2m}{{\hbar}^2}(E-V(x))}} +A_2 e^{-ix \sqrt{\frac{2m}{{\hbar}^2}(E-V(x))}}$$ If we have an infinite potential well: ## V(x)=\begin{cases} \infty \quad x\ge...

Good day, I get confuse about the term used. Can anyone help me to explain: Tripartite system. Three qubit system. Tripartite entanglement. I really need help for me clarify these term. Thank you very much for helping me.

Hi, For a harmonic oscillator in 3D the energy level becomes En = hw(n+3/2) (Note: h = h_bar and n = nx+ny+nz) If I then want the 1st excited state it could be (1,0,0), (0,1,0) and (0,0,1) for x, y and z. But what happens if for example y has a different value from the beginning? Like this...

Everybody knows what is the Wave Function is. $$\Psi=\space e^{i(kx-\omega t)}$$ or $$\Psi=\space cos{(kx-\omega t)} \space - \space isin{(kx-\omega t)}$$ But can anyone tell me how it is derived. Since Schrodinger Equation is derived so easily using this Wave Function. I think it is necessary...

Good day, From my reading according to negativity for tripartite state, it is given as below; $$N_{ABC}(\rho)=(N_{A-BC}N_{B-AC}N_{C-AB})^{1/3}$$ with $$N_{I-JK}=-2\Sigma_i\sigma_i(\rho^{TI})$$ where $$\sigma_i(\rho^{TI})$$ being the negative eigenvalues of $$\rho^{TI}$$, the partial...

like in sound waves pressure varies(oscillates) and in light electric and magnetic field oscillates

If the amplitude of gravitational waves, frequency of gravitational waves and the vector potential of magnetic field in surrounding of such waves are known then what would be the easiest way to calculate resultant acceleration of electrons? My above question is based on the various researches...

Good day, Homework Statement I want to make a measurement on qubit by using formula von Neumann entropy using Mathematica given as below; Homework Equations (ρ)=−Tr(ρlog2ρ) The Attempt at a Solution The ρ={{0.5,0},{0,0.5}}My problem is, when I make the log2{{0.5,0},{0,0.5}} I get the...

Are metals better conductors in the presence of visible light? Considering photons in visible spectrum are not energetic enough to induce emission from a metal surface but they do cause the ejection of 'conduction electrons' which are bound to the metal by a few electron volts.

$$|\psi(x_1,x_2)|^2=|\psi(x_2,x_1)|^2$$ $$\psi(x_1,x_2)=+/-\psi(x_2,x_1)$$ How do they convert they former into the latter one? Is it due to the modulus? I know the latter can also be written as $$\psi(x_1,x_2)=e^{i\alpha}\psi(x_2,x_1)$$ where the exponential is the phase used to replace +/-...

Hi. I'm wondering how different potentials, such as the Dirac-Delta potential, linear potential, quandratic potenial, etc., are implemented experimentally. I only understand how the Schrodinger equation is solved if these are the potentials and I'd like to have a better understanding of quantum...

Hello everyone. A Philosophy of Science friend showed a site where you can upload your paper and then you will be fairly quickly reviewed by your peers and this will be published alongside your paper. It seems to me this is a very good way to proceed; you may get assessment from the very top...

i know it sounds stupid, but i can't seem to find an answer to it where did the energy went? you can't just just destroy energy, but when you red shift a gamma CMB into a microwave CMB, the energy has go to go somewhere...? it's not like one gamma photo spitted into many microwave, cause that...

Hello. Well, each and everyone of us know that Like Charges repel, while unlike charges attract. That's a normal high school physics fact. But what's the reason for that? Is it just an experimental fact, or even does have theoretical significance? Please do help. Thanks a lot Swapnil Das.

Hi, I just completed my second year of my physics undergraduate degree. And recently did a course on Quantum Mechanics. I have a few questions regarding the basic theory and postulates, probably, because due to lack of full clarity. So, Consider a wave function ψ(x,o), which is well behaved and...

Using electrical potential energy =1/4πεo Q1Q2/r , a particle further away from nucleus has lower magnitude of energy Using coulomb's law, a particle further away from nucleus experiences weaker attraction, hence less energy is needed to maintain orbit* around that e-shell compared to a...

Using electrical potential energy =1/4πεo Q1Q2/r , a particle further away from nucleus has lower magnitude of energy Using coulomb's law, a particle further away from nucleus experiences weaker attraction, hence less energy is needed to maintain orbit* around that e-shell compared to a...

As Avagadro states: "One mole of an ideal gas at STP occupies 22.4 liters." This doesn't seems counterintuitive since we know that we need a volume to compress the gas. But how can we explain quantum ideal gases. Especially in my case, Bose gases. Since well-known example is Helium 4, we might...

Homework Statement I have a spin operator and have to find the eigenstates from it and then calculate the eigenvalues. I think I managed to get the eigenvalues but am not sure how to get the eigenstates.Homework Equations The Attempt at a Solution I think I managed to get the eigenvalues out...

Homework Statement For a 1-dimensional simple harmonic oscillator, the Hamiltonian operator is of the form: H = -ħ2/2m ∂xx + 1/2 mω2x2 and Hψn = Enψn = (n+1/2)ħωψn where ψn is the wave function of the nth state. defining a new function fn to be: fn = xψn + ħ/mω ∂xψn show that fn is a...