States Definition and 1000 Threads

Homework Statement Given the coherent state of the harmonic oscillator |z>=e^{-\frac{|z|^2}{2}}\sum_{n=0}^\infty\frac{z^{n}}{\sqrt{n!}}|n> compute the probability for finding n quanta in the sate |z> and the average excitation number <z|n|z>Homework Equations...

A voltaic cell is composed with reactants and products in their standard states.So when it operates,the concentration of all substance must change,it should no be hold.Am i right?

Is there any state of matter for fire or electricity ? If yes, then what is the state of matter ?

Homework Statement The wavelength of the radiation emitted when the outermost electron of Al (Aluminum) falls from the 4s state to the ground state is about 395 nm. Calculate the energy separation (in joules) between these two states in the Al atom. Draw an energy level diagram of the states...

In basic chemistry, we "fill up" the energy levels of an atom by putting two electrons in each energy level. The justification for this (that I've seen) is that the Pauli exclusion principle only allows one electron per state and there are two states in each energy level (spin up and spin down)...

Homework Statement I'm supposed to calculate all the states for a system with ##l=1## and ##s=1/2##. Let's say ##\vec{J} = \vec{L} + \vec{S}##. I want to find the Klebsch-Gordon coefficients. I know that said system has 2 towers, one with ##j=3/2## and the other with ##j=1/2##. I've...

Homework Statement The emission spectrum of thermally excited sodium atoms practically consists of a single intensive line at 589 nm wavelength. What is the energy difference (in eV units) between the excited and ground states of the sodium atom? Homework Equations E = hc/lambda, we also know...

Hello I'm trying to work through a see-saw model derivation and I've become a bit stuck. I've tried lots of sources but the difference in conventions doesn't fill me with confidence when combining these sources. I need to get from ## \overline{ \nu_L^c } \nu_R^c + h.c ## to ## \overline{...

Let: $$x_1=A\sin{\omega t}$$ $$x_2=\dot{x}_1=A\omega \cos{\omega t}$$ $$y=A\omega$$ We want to represent this system in a state space model. The state transition matrix read: $$A=\begin{bmatrix} 0 & 1 &\\ -\omega^2 & 0 \\ \end{bmatrix}$$ I am not sure what the output matrix will be like. Can we...

Homework Statement A certain system has 6 × 10^24 degrees of freedom. Its internal energy increases by 1%. By what factor does the number of accessible states increase? Homework Equations \Omega = E^{N\nu/2} \nu is the degrees of freedom, and N is just 1, so we can ignore that. So the exponent...

In my particles course, it says we will use Fermi's golden rule to work out rates. FGR is: Γ=2π|Mfi|ρ For the case of non-relativistic phase space, my notes say the density of states can be found as follows (pretty much word for word): Apply boundary conditions Wave-function vanishing at box...

Tell me if the following is correct. For a simple infinite square well potential, the solutions to the Schrodinger equation are \Psi_n(x)=\sqrt{\frac{2}{a}}sin(\frac{n\pi x}{a}), then you plug in the appropriate value for n and operate on the function accordingly to get your observables. Then...

Homework Statement (a) the density of k-states g(k) = L^2*k/2*Pi. (b) the density of states g(E) = L^2*m/Pi*h^2 (c)The density of states per area n2D(E)=m*/Pi*h^2 (d) Sketch a graph of n2D(E) vs E. (e) Calculate n2D(E) as a quantity. The questions don't have to be answered in full a...

1)So from my understanding, as long as ##E>0## you will have scattering states and these scattering states will always result in an imaginary ##\psi##, but bound states can also have an imaginary ##\psi##? Is this correct and or is there a better way of looking at this maybe more conceptually...

I'm working on a problem out of Griffith's Intro to QM 2nd Ed. and it's asking to find the bound states for for the potential ##V(x)=-\alpha[\delta(x+a)+\delta(x-a)]## This is what I'm doing so far: $$ \mbox{for $x\lt-a$:}\hspace{1cm}\psi=Ae^{\kappa a}\\ \mbox{for $-a\lt x\lt...

I am a little confused about exercise 1.2 in the book "Quantum Computation And Quantum Information" By Michael Nielson. The question is: Explain how a device which, upon input of one of two non-orthogonal quantum states |a> or |b> correctly identified the state, could be used to build a device...

Homework Statement Consider a particle of mass m in the ground state of a potential well of width 2 a and depth. the particle was in the ground state of the potential well with V0 < Vcritical, which means the well is a narrow one. At t = 0 the bottom of the potential well is shifted down to Vo'...

In some quantum textbooks [1], the tunneling transmission formula depends only on the density of states of 2 regions (DOS) involved in tunneling. (T(E)=C×DOS1(E)×DOS2(E), where C is constant). However, in Landauer transmission formula (without tunneling) the transmission depends on both DOS and...

Hi, Following electromegnetic field quantization, one ends up with the fock states as the energy eigenstates of the quantized field. Considering a single mode field, the set of fock states are the single-mode energy eigenstates. Yes, these fock (or number) states are just the eigenstates of the...

I am writing a book, and since I am a science layman, just wanted to check to see if you find the following paragraph I wrote to be correct from a physics standpoint. The idea here is that "a single, simple substance or field can contain regions which are in different states." I would greatly...

Homework Statement Hi! My issue here is that I need to find the bound states (if any) of the potential: U(r)=-C\frac{s_1\cdot \hat{r}\, s_2\cdot \hat{r}-s_1\cdot s_2}{r}. Here s_1 and s_2 are the spins of the two spin-one particles involved in this interaction. The two particles have...

I have learned the fact from Peskin QFT book,that one-particle state presents a delta function form in spectral function at s=m^2,while multiparticle states present a continuous form begin at s=4m^2,but i don't really understand the reason.What cause the difference between one-particle state and...

Homework Statement For an electron in a uniform magnetic field, say B\hat{z} with no angular momentum, the Hamiltonian can be expressed as \hat{H}=\frac{1}{2m}\Big(\hat{p}_x^2+\frac{mω^2}{2}\hat{x}^2\Big)+\frac{1}{2m}\Big(\hat{p}_y^2+\frac{mω^2}{2}\hat{y}^2\Big) Which is equivalent to two...

Homework Statement A particle is moving in one dimension, estimate the number of quantum states available to that particle if it is an electron confined in a region 10-9m long with speed less than 107 m/s (less than meaning velocity is between 107 and -107 m/s) Homework Equations...

Homework Statement These are rather simple questions but the rules for all of this are not quite clear to me yet. I'm to determine whether or not the following states are "legal" and if not I should normalize them. a. ##\frac{1}{√385} ∑_{x=1}^{10}x^2 |x>## b. ##\frac{1}{√2}...

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...

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. Equations g(E)=\sum_{s}\delta(E-E_s) N=\int dE g(E) The "density of states" need not (but it most often does) refer...

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...