States Definition and 1000 Threads

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...

Hello everyone, My understanding is that a two-quantum state system is simply a system that can only be in two states. That is equivalent to say that the observable of interest that is being considered can only have possible values. Is that the case? If so, a classical bit can have two values...

I was just reading a paper <predatory publisher reference deleted> There is an argument (originally by Spekkens), in Section 2.1, that is supposed to be against psi-ontic interpretations. As I understand it, it's that if someone hands you a particle in state x+ or y+ you cannot tell the...

Hello. I think excited states of Argon atom is described by j,l coupling written as (2s+1)[K]J. However, when I read some papers describing cross section data for Argon atom, data are quoted with strange notation, Paschen notation. I tried to study the Paschen notation and found that its form...

I was reading Peskin&Schroeder's QFT book, and there was some discussion about how ##\left|0\right>##, the ground state of a free field and ##\left|\Omega \right>##, the ground state of an interacting field differ from each other, and they outlined how the latter can be obtained by propagating...

Does energy have different states analogous to the solid, liquid, gas, and plasma states of matter? Would they be the same as "forms of energy" described here? https://en.m.wikipedia.org/wiki/Forms_of_energy

Homework Statement Calculate the single-particle density of states ##g(\epsilon)## for the dispersion relation ##\epsilon(k) = ak^{\frac{3}{2}}## in 3D. Use ##g(k) = \frac{Vk^2}{2\pi^2}##. Homework EquationsThe Attempt at a Solution This question is worth lots of marks. My solution is a few...

Hi guys! I study Electrical Engineering and, don't-know-why, I don't know anything about state space. Now I'm working on a project where I have a non-linear system. The first task in the project is to separate the linear and the non-linear part of this system, and then obtain the state space...

If there are 3 positive charges of +1, +3, +5 coulombs equidistant from a negative charge of 1 coulomb what positive charge will this negative charge be attracted to ? Is the result different if the charges exist in a “bound” state (resulting in electrovalent compounds) where a positive charge...

It will sound a little bit stupid, but Ill ask anyways: I have two series systems, the second is an UKF (Uscented Kalman Filter). I was told to reduce the first system in order to that the UKF estimate less states. My question is: What exactly do the states represent? I mean, if I have a...

In solid state physics you can calculate the band structure of a material, which is effectively the dispersion E_n(k), which depends on the wavevector as well as the band index. What I don't understand is this: Which states are occupied in a band? With this I mean: Which k values correspond to...

I read that states are positive operators of unit trace - not elements of a vector space. Is it referring to quantum states or all classical states? I know operators are like minus, plus, square root and vectors are like rays in Hilbert space.. but why can't quantum states be vectors when in...

Hello everybody, - In quantum mechanics, the state ## | \psi \rangle ## of a system that is in thermodynamic equilibrium can be expressed as a linear combination of its stationary states ## | \phi _n \rangle ## : $$ | \psi \rangle = \sum_n c_n | \phi _n \rangle $$ It permit us to express the...

What is the difference between two single-photon Fock states ##|1\rangle |1\rangle## and one two-photon Fock state ##|2\rangle## (all in the same mode)? In both cases the mean photon number is 2. How do we distinguish them experimentally?

We learned that we can use the ladder operator to obtain the states of a quantum oscillator. However, I see no direct evidence to show that the solutions are complete. I mean, how can we know the energy state follows E is (E+hw). Why can't we have some more states in between? Does the derivation...

I read that hadrons are in colour singlet state and that gluons are not and that the colour singlet gluon is forbidden for the reason of making strong force a long range force otherwise (and that SU(3) has 8 generators and thus 8 gluons) but my question is: are mesons in a colour singlet state...

No. This is a noncovariant, observer-specific view.In the covariant, observer-independent view of fields, states are labeled instead by the causal classical solutions of hyperbolic field equations. On the collection of these the Peierls bracket is defined, which is the covariant version of the...

Homework Statement Consider a spin state |n; +> where n is the unit vector defined by the polar and azimuthal angles θ and φ and the spin state |n'; +> where n' is the unit vector defined by the polar and azimuthal angles θ' and φ'. Let γ denote the angle between the vectors n and n': n⋅n' =...

Hello, In the four maximally entangled two-qubit Bell states, what is the difference between the first and the second states, similarly, the difference between the third and the fourth states. What the different in signs mean( +,-)...

Let's say there are two 1/2 spin particles, one in state 1/√2 |up> + 1/√2 |down> and the other in the state - 1/√2 |up> - 1/√2 |down> Both particles then have an equal chance of being measured to be in either the up or down states. Is there any physical difference between these or are they...

Hello, can someone give an example for an incoherent State --> a formula is here on page 7 : http://quantumcorrelations.weebly.com/uploads/6/6/5/5/6655648/2016_robustnessofcoherencetalk.pdf I know that coherenc is e.g. a superposition of e.g. Spin-Up and Spin-Down [z] or so... But i have no...

As the title says, why does the set of hydrogen bound states form an orthonormal basis? This is clearly not true in general since some potentials (such as the finite square well and reversed gaussian) only admit a finite number of bound states.

Consider a simple two level atom system,|1>,|2> (not degenerate) interacted with monochromatic laser, of which the frequency is exactly resonant with the |1> to |2> transition. The evolution start from {1>. As far as I understand, the dressed degenerate state |1>|n> and |2>|n-1> will get...

We are doing spectroscopy on some semiconductors covered by a layer of Aluminium. My professor says it might be a challenge for to see the valence band structure of the semiconductor because the metal has a high density of states at the fermi level. Does this make sense to you? Does a metal have...

Here is an interesting article off of phys.org that I really liked. http://phys.org/news/2012-08-caught-camera-quantum-mechanics-action.html What I found interesting is its premise of visually capturing multiple quantum states so that one could personally inspect a lot of these issues that...

Hello! (Wave) I want to find a DFA equivalent with the following: Do we have to follow the following procedure? If so do we have to find the transition function having the following states? $$\{A\} , \{ B \}, \{ C \}, \{ A,B \}, \{ A,C \}, \{ B,C \}, \{A,B,C\}$$

I've found online that the coherent state of the harmonic oscillator is |\alpha \rangle = c \sum_{n=0}^\infty \frac{\alpha^n}{\sqrt{n!}} | n\rangle where |n\rangle = \frac{(a^\dagger)^n}{\sqrt{n!}} |0\rangle and |0> is called the initial state. I've some code where I need to have this...

Someday if there are experiments that can show it.. it's still a possibility that in Quantum Darwinism or Everettian, pointer states are primitives? This means if there are no pointer states. The universe won't be classical at all. Because there are arguments that they have to conform to...

Can anybody give a natural interpretation of operators and states in the Heisenberg Picture? When I imagine particles flying through space, it seems that the properties of the particles are changing, rather than the position property itself. Is there any way I should be thinking about these...

I am following the derivation shown in this link on adiabatic passage. I have posted one part below: I am simply wondering how this expression was derived and how it indicates the probability of being in a state that is different from the initial state? How exactly is this represented by...

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...

In statistical physics the calculation to obtain the density of states function seems to involve an integral over an eighth of a sphere in k-space. But why do we bother moving from n-space to k-space, if there's a linear relation between n and k i.e. n = (L/π)k ? Why don't we just integrate over...

Hi, I'm trying to learn some QFT at the moment, and I'm trying to understand how interactions/nonlinearities are handled with perturbation theory. I started by constructing a classical mechanical analogue, where I have a set of three coupled oscillators with a small nonlinearity added. The...

Hi. I don't understand what is meant by the eigenvalue α of a coherent state where a | α > = α | α >. The eigenket |α > is an infinite superposition of the number states , ie | α > = ∑ cn | n > and for each number state a | n > = √n | n-1 >. So for each number state the eigenvalue of the...

Hello, I'm stuck with this exercise, so I hope anyone can help me. It is to prove, that the density of states of an unknown, quantum mechanical Hamiltonian ##\mathcal{H}##, which is defined by $$\Omega(E)=\mathrm{Tr}\left[\delta(E1\!\!1-\boldsymbol{H})\right]$$ is also representable as...

Hi, guys. If you are given one state of the baryon decuplet (the upper-right state ##\Deltaˆ{++}=uuu##, for instance), you can use the ladder operators to get the other states of the decuplet. When I apply ##T_-## to uuu and normalizing, I get ##\frac{1}{\sqrt{3}}(duu+udu+uud)##. However, in...

Hi, I know how to calculate density of states for both cases, but it is not clearly to me how I can go from 3D case to 2D. I have energy from infinite potential well for 3D $$E=\frac{\hbar \pi^2}{2m}(\frac{n_x^2}{l_x}+\frac{n_y^2}{l_y}+\frac{n_z^2}{l_z})$$ let make one dimension very small...

Hello! When computing the density of states of electrons in a lattice, a material with dimensions L_x, L_y, L_z can be considered. The allowed \mathbf{k} vectors will have components k_x = \displaystyle \frac{\pi}{L_x}p k_y = \displaystyle \frac{\pi}{L_y}q k_z = \displaystyle \frac{\pi}{L_z}r...

Why cannot we represent mixed states with a ray in a Hilbert space like a Pure state. I know Mixed states corresponds to statistical mixture of pure states, If we are able to represent Pure state as a ray in Hilbert space, why we can't represent mixed states as ray or superposition of rays in...

We are taught that the forces of attraction in a liquid are lesser than those in a solid. What is the reason? Is it because the intermolecular spaces are large or is it because the individual attractive force of the molecule is less?

If I have a spin 1/2 particle eg electron in an isolated box can I state for definite that there is a 50% chance of it being spin up and 50% spin down ? If I know the probability of it being spin up and spin down how do I know if it exists as a pure state of a superposition of spin up and spin...

Homework Statement Consider the following example from a previous exam. We are to predict the spin and parity for F(A=17,Z=9), Florine, in the ground state and the first two excited states using the shell model. Ground state: Neutrons: (1s 1/2)^2 (1p 3/2)^4 (1p 1/2)^2 Protons: (1s 1/2)^2...

I have a question, and it is this: why is it that your hand can go through a gas or liquid while the same can't be done with solids? Is it because of density?

Homework Statement What are S, L and J for the following states: ##^1S_0, ^2D_{5/2} ^5F_1, ^3F_4## Homework Equations The superscript is defined as: 2S + 1 The subscript is defined as: J = L + S The letter denotes the angular momentum number (s, p, d, f...) starting at s = 0. The Attempt at a...

Homework Statement The three lowest energy states of an infinitely deep square well (of width L, between x=0 and x=L) are: Ψ1(x,t) = N sin(πx/L) e-iω1t Ψ2(x,t) = N sin(2πx/L) e-iω2t Ψ3(x,t) = N sin(3πx/L) e-iω3t N = sqrt(2/L) is the normalization, to make the total probability = 1. Each wave...

'In the SU(3) quark model there are two singlet vector states $$|\omega_8 \rangle = \frac{1}{\sqrt{6}} \left(|u \bar u \rangle + |d \bar d \rangle - 2 |s \bar s \rangle \right) $$ belonging to the octet and the pure singlet state $$|\omega_1 \rangle = \frac{1}{\sqrt{3}} \left(|u \bar u \rangle +...

Hello, I am a 40 year old Computer Scientist by education and profession. Education in general is my hobby. I am currently listening to a lecture on quantum mechanics: The Teaching Company's Quantum Mechanics Physics of the Microscopic World. Very good. So please excuse my nievity and ignorance...

Homework Statement Here is the problem: http://imgur.com/XEqE4SY Homework Equations |psi_s_ms> = |s, ms> ⊗ Σ D_i_j |psi_i, psi_j>[/B]The Attempt at a Solution I know the singlet state in the |s, ms> basis is |0,0> = (1/sqrt(2))[ |up, down> - |down, up>] and that the hamiltonian for this...

Can someone explain the difference using concrete examples. I will attempt to explain my current understanding by example; A H atom has different energy levels which can be exactly described by algebraic functions with quantum numbers n, l etc. An electron can be excited from say the ground...

Looking (if possible for some of you) a concise but non mathematical explanation of the terms localization and delocalization? This questions is related to Quantum Molecular Physics. When reading a paper of Spectroscopy and allowed transitions, I encounter the following phrase " [Intersystem...