States Definition and 1000 Threads

Hi all, I were wonder how the particles which consisting of four quarks like Z(4430) state ( ##c\bar{c}d\bar{u}## ) can be theoretically explained ? Of course, this is beyond the the quark model, where the SU(3) group has for example, representations with dimensions 3 (corresponding to...

Recently, the properties of nonequilibrium many-body quantum systems have aroused great curiosity of physicists. Numerous papers have been published about this area. But how do we measure how far the system is from equilibrium states? There are several proposals have been published, for...

Hi, can smart people please assist me with understanding something: why doesn't the "final" observation at the back screen create the same kind of effect as an observation made before the particle hits the back screen? Simple term please; no PhD here. Thanks.

For school my teacher told me there were 3 states of matter but the internet told me there were 5. Help?

Are lower energy electron orbitals always closer to nucleus than higher energy orbitals? Is this energy proportional to the inverse square law and Coulomb's law? When an electron jumps down to a lower energy orbital, is potential energy not just converted to kinetic energy, and so where does...

Hi everyone I am investigating spontaneously generated coherence(SGC), I found that it happens when an excited atomic state decays to one or more closed atomic levels so that atom goes to a coherent superposition of states , Effect of State Superpositions Created by Spontaneous Emission on...

Hello Forum, When a system is in a particular state, indicated by a |A>, we can use any basis of eigenvectors to represent it. Every operator that represents an observable has a set of eigenstates. I bet there are operators with only one eigenstate or no eigenstates. There are operators, like...

Hi guys, Sorry if this isn't quite the right place to post this, but I have a few conceptual questions that I'd like to clear up about time evolution of a quantum state. Firstly, what is the exact argument for the evolution operator \hat{U}\left(t,t_{0}\right) being independent of the initial...

Dear All, for different oxidation states of the same element in X-ray photoelectron spectroscopy measurements, should the full width half maximum (FWHM) value be the same for all? Is this a parameter to fix in this case for the fitting? I am studying an amorphous transition metal oxide thin...

Hi all, Just a quick theory based question regarding the Zeeman Effect. The effect of the applied magnetic field in the Zeeman effect separates the possible angular momentum states (each of which has a magnetic dipole associated with it) into different energy levels. However, if the...

I've heard any many places that the density of states (DOS) can be determined from an x-ray photoelectron spectroscopy (XPS) spectrum. Perhaps someone more knowledgeable than me can explain how this is done, or can direct me to a good resource? Thanks!

Hi I'm going through some course notes for QM. A state for a 2 qubit system is called non-entangled (or separable) if it can be decomposed in a tensorproduct of 2 single qubit states. If we write a general state as |\psi> = a_{00}|00>+a_{01}|01>+a_{10}|10>+a_{11}|11> A theorem states...

Hello. I have been in contact with some papers that use DFT softwares for calculating properties of solids, nanoparticles, etc and a lot of them comes with colorfull plots of density of states. I know the density of states gives the number of electrons in the range of energy, but what I don't...

[SIZE="4"]Definition/Summary This term most commonly refers to the number of quantum states having energy within a given small energy interval divided by that interval. [SIZE="4"]Equations g(E)=\sum_{s}\delta(E-E_s) N=\int dE g(E) The "density of states" need not (but it...

The relativistic mass-energy-momentum relation m^2=E^2-p^2 predates quantum mechanics by a couple of decades. It allows a particle such as an electron to have a negative mass-energy. If it's 1906, and you're shown this equation, do you have any way to show that the negative-energy solutions...

Homework Statement let [1> and [2> mutually orthogonal states (eigenstates of some Hermitian operator). the Hamiltonian operator is given by H=c[1><2]+c[2><1], where c is a real number. (a) calculate the eigenstates and corresponding eigenvalues of H (b) if the initial state of the system...

It's known that the Density of States in 2D is given by, g_2(E)dE = \frac{a^2m}{\pi\hbar^2}dE The density of states in 1D and 3D are as follows, g_1(E)dE = \left(\frac{a}{\pi}\sqrt{\frac{2m}{\hbar^2}}\right)\frac{1}{\sqrt{E}}dE g_3(E)dE =...

Hi. I am currently studying about representations of Lie algebras. I have two questions: 1. As I understand, when we say a "representation" in the context of Lie algebras, we don't mean the matrices (with the appropriate Lie algebra) but rather the states on which they act. But then, the...

Hi all, So I was recently set straight on the fact that bound state does *not* necessarily mean E<0 but rather is the statement that E<V(+/- infinity). So how do we apply this definition to the infinite square well where the potential at +/- infinity vanishes, and yet the bound states have...

I am watching James Binney's QM lectures on iTunes University, and also going through his free textbook. He is a tough teacher, but I love how many misconceptions he points out, and some of the points he makes are very subtle and mind blowing when the lightbulb comes on. I am confused on...

Is is possible to find unoccupied states below fermi energy?? Or all states below fermi energy are always occupied?

Yale professor James Rothman, winner of the 2013 Nobel Prize in Medicine, to prospective biomedical researchers at a panel discussion about declining federal funds for science research in Washington, D.C. last year...

Hi everyone, I have a rather fundamental question about building oscillator wavefunctions numerically. I'm using Matlab. Since it's 1/√(2nn!∏)*exp(-x2/2)*Hn(x), the normalization term tends to zero rapidly. So for very large N (N>=152 in Matlab) it is zero to machine precision! Though asymptotic...

Hello everyone. I was yesterday asked in an interview to draw a gaussian curve. I drew. And then they asked in what region would this give rise to bound states? I am really confused how to conclude if a function gives bound state or not. Please help. Thanks.

Is it true that there always exist a unitary matrix that can take a state vector of an arbitrary pure state to another arbitrary pure state ? (of course assuming same hilbert space). If true, how do we prove it ? it look like it is true via geometrical arguments but i have not been able to...

Hi everyone, I've been studying the so-called XYZ spectroscopy and the existence of possible 4-quark states. The LHCb collaboration recently confirmed the existence of a particle called Z(4430)^-. This particle is the unambiguous evidence for the existence of 4-quark states. From what I...

Homework Statement Particle originally sits in ground state about x=0. Equilibrium is suddenly shifted to x=s. Find probability of particle being in new first excited state. Homework Equations The Attempt at a Solution Shifted wavefunctions are for ground state: ##\phi'_0 =...

Homework Statement Part (a): Plot fermi energy as a function of N Part (b): Derive the density of states and find its value Part (c): How many atoms reside at 20% of fermi energy? Estimate diameter of cloud Part (d): For the same atoms without spin, why is the cloud much smaller...

Homework Statement Given the potential V(x) = - 1/ sqrt(1+x^2) Consider this in a 50x50 matrix representation of the hamiltonian in the basis of a one dimensional harmonic oscillator. Determine the eigenvalues and eigenvecotrs, the optimal parameter for the basis, and cop ate the...

Please help me with the question in the picture about pull-up and pull-down networks.

Greetings, I have been studying stat mech lately, and while I have gotten good at using partition functions to solve problems, I wanted to check my interpretation of what a partition function is, and especially to contrast it with the number of states. So, I'm just looking for a yes or no to...

We've been assigned Griffiths QM for undergraduate physics. I don't particularly like it, but anyway. It says that if the eigenvalues an observable are continuous then the eigenfunctions do not represent physically realisable states. So the eigenfunctions of the hamiltonian are discrete and...

Homework Statement Part (a): Show probability to transit from state i to j is given by: Part (b)i: Use answer in part (a) to find probability Part (b)ii: Use time evolution to find probability Homework Equations The Attempt at a Solution Part (a) was alright, bookwork question on time...

The question is to calculate the time evoution of S_{x} wrt <\Psi(t)\pm l where <\Psi\pm (t) l= ( \frac{1}{\sqrt{2}}(exp(^{+iwt})< \uparrow l , \pm exp(^{-iwt})< \downarrow l ) [1] Sx=\frac{}{2}(^{0}_{1}^{1}_{0} ) Here is my attempt: - First of all from [1] I see that l \Psi\pm (t) > = (...

Homework Statement This is not a homework question, just me trying to wrap my head around things. My probability class talked about Markov chains for less than 2 hours worth of lecture, and I've been super sick lately, so I'm still a little confused. If we're considering real world...

In order to apply perturbation theory to the ψ_{200} and ψ_{210} states, we have to solve the matrix eigenvalue equation. Ux=λx where U is the matrix of the matrix elements of H_{1}= eEz between these states. Please see the matrix in attachment 1. where <2,0,0|z|2,1,0>=<2,1,0|z|2,0,0>=3a_{o}...

Homework Statement Consider an ideal system of 5 non-interacting spin 1/2 particles in the absence of an external magnetic field. What is the probability that n of the five spins have spin up for each of the cases n = 0, 1, 2, 3, 4, 5? Homework Equations I'm guessing \frac{N!}{n!(N-n)!}...

Number of Spin "s" States Homework Statement For a system of two identical particles with spin s, determine the number of symmetric and anti-symmetric spin states. 2. The attempt at a solution This does not seem like a problem that is that difficult, but I am having some trouble...

Homework Statement I am studying my lecturer's notes and in this part he uses a delta potential to illustrate a simple example of Fermi's golden rule, that the rate of excitation is ##\propto t##. Homework Equations The Attempt at a Solution I've managed to get the bound states, by solving...

Why are exited states of an Isotope metastable? Is it because they have a large spin and therefore the final states they decay to have to be excited as well? And therefore they have less energy gain? I am thinking about 116 In (the 1+ and 5+ state) both can undergo a β- decay. Thank you!

Does atoms in a crystal have energy states like electronic states? it is according to Einstein relation for harmonic oscillator.E=nhw

Homework Statement Calculate the single particle density of states for massless particles with dispersion E=h_bar ck for a 3D cube of volume V Homework Equations E=pc, p=E/c, dp=dE/c, d^3p = 4pi*p^2 dp k=sqrt(k_x^2+k_y^2+k_z^2) k_j = 2pi/L l_j (j=x,y,z) The Attempt at a Solution I...

I am a little confused by an elementary point. Something must be wrong with the following: On one hand, a Hermitian operator (which is not necessarily unitary) takes one state to another state. Hence a state need not be represented as a unit vector; its norm can be greater (or less than)...

I am reading an article on wikipedia about ground state and it says - The ground state of a quantum mechanical system is its lowest-energy state; the energy of the ground state is known as the zero-point energy of the system. An excited state is any state with energy greater than the...

why massless particle, such as photon, can only have two helicity states? Photon's helicity is 1,-1. Helicity zero is forbidden. why?

Given the half reaction: 2H2O(l) → O2(g) + 4H+(aq) + 4e- How would you set up the Q equation for this reactions? Would it be Q = [H+]4 only or do we assume the partial pressure of oxygen gas is 1 atm? Is there a general way to write the Q value for species in different states?

As mixed states and density matrices are the generalization of pure states, i wondered if it was possible to prepare a given mixed state. I know that decoherence give mixed states. Are there other ways to get them? measurements on pure states always give pure states (POVM also). So how?

Greetings, While attempting to learn something about cryptography, I have repeatedly encountered a commonly quoted argument about the minimum energy required to cycle a 256 bit counter through all its states. It says that the absolute minimum energy required to change the state of a bit is...

I am a retired electrical engineer, now able to get back to studying what I really enjoy - mathematics and physics. As a genuine old geezer, my modern physics knowledge, which was never very deep, is now way out of date. I purchased a copy of "Modern Physics", by Kenneth Krane, and have been...

Homework Statement An LTI system is given in state-space form, \left( \begin{array}{cc} \dot{x_{1}} \\ \dot{x_{2}} \end{array} \right) = \left( \begin{array}{cc} -1 & 0.5 \\ 1 & 0 \end{array} \right) \left( \begin{array}{cc} x_{1} \\ x_{2} \end{array} \right) + \left( \begin{array}{cc} 0.5 \\...