States Definition and 1000 Threads

Hi all, I've been reading section 5.3 of Peskin and Schroeder, in which the authors discuss the production of a bound state of a muon-antimuon pair close to threshold in electron-positron collisions. Here \xi,\xi' are the Weyl spinors used to construct the Dirac spinors for the muon and...

I recently got (re)interested in C* algebras. Poking around, I gathered that there is some way of constructing a C* algebra corresponding to a finite graph. I'll put some links here in case anyone knows anything about this. At the moment I'm ignorant but hope to find out more. No idea in...

Homework Statement This is a two part question I can do about half of each but get a little lost when trying to finish. I have written all the values below but just in case the full question is here (sorry about clarity) - http://screencast.com/t/jHQTMFnYOhp λ = 308nm T = 2000K population...

Hey, I have question on Helium with one electron in it's ground state orbital 1s and the other in the 2s orbital. We have S=1 states reffering to the spin symmetric triplet state and S=0 reffering to the spin antisymmetric singlet state, due to quantum effects of the electron-electron...

Hi all, I was deriving the free electron gas for practice in 1, 2, and 3 dimensions, and I started wondering why they have different dependencies on energies and what that means. I got: 1D: ##g(E) = \frac{1}{\pi\hbar} \sqrt{\frac{2m}{E}}## 2D: ##g(E) = \frac{m}{\pi\hbar^2}## 3D: ##g(E) =...

Bound vs "not"bound states Homework Statement Hi, I do not understand how two bound state wavefunctions differ from not bound state wavefunctions. To be more precise I m thinking about the graphical representation. [b]ons[/b2. Relevant equati The Attempt at a Solution I speculate that bound...

I have diagonalized a Hamiltonian matrix many times with a varying parameter (varying magnetic field). This gives me the eigenstates and eigenvalues of the matrix for the different field values. I now need to track the diabatic states through (avoided) level crossings of the eigenvalues...

Hi everyone. I'm trying to give myself a primer in quantum mechanics/chemistry as I'm doing a literature review on NMR and its applications. I have a few questions. (I'm an electrical engineer, I understand our troubled past, and hopefully our peoples can find a peace) I'm trying to...

can particles be entangled on any property having more than two states? Photons can be entangled on spin. however spin has only two states: Up or down, plus or minus So the question is: is there any property (having more than two states) on which photons/electrons/bucky-ball can be...

Hello, I am trying to understand the idea of using analytic continuation to find bound states in a scattering problem. What do the poles of the reflection coefficent have to do with bound states? In a problem that my quantum professor did in class (from a previous final), we looked at the 1D...

Hi everyone Homework Statement I have to particles without a potential. The coordinates are r_1 and r_2 (for particle 1 and 2). Both have orthonormal states |↑> and |↓>. I shall show that the expectation value is the following, where as |↑↓> is a product state d^2=\langle \uparrow...

Hey, I have to express the combined system state of j=5/2, m=5/2 in terms of the products of states j1,m1 and j2,m2. \mid j,m> =\mid\frac{5}{2},\frac{5}{2}>\: ,\: |j_1,m_1> \& |j_2,m_2> I know that one way of achieving this is for j1=3/2 and j2=1 but I'm not sure how to express this - I...

Alright, I'm back with yet another question... So the prof was explaining that the energy in an infinite cubical well is E((h2∏2)/2ma2))(nx2+ny2+nz2) Which is all well and good, and he gave us the example of: ψ1,2,1 = E = 6((h2∏2)/2ma2)) And with little explanation mixed it up once...

Hi, Hope you can give me an answer regarding this trellis diagram. why in this picture of a general first-order markov chain of 2 states,we should know the prob. of each state at each time? A general first-order markov chain, can be Time-dependent(non stationary) so Transition prob. can change...

Maybe the answer to this should be obvious, but if the quantum harmonic oscillator has a natural angular frequency \omega_0, why do the excited states vibrate with higher and higher angular frequencies? How do we obtain these frequencies? Thanks!

It is said that all non-strange non-baryonic states are eigenstates of G-parity. And all members of an isospin multiplet have the same eigenvalue. Can anyone give me a proof to these two statements, or show me where I can find one? In addition, the composite state consisting of K^{+}K^{-} should...

Hello, I need help with 2 homework questions: Also this question:

Given a simple atom like the Bohr atom (and possibly generalized to any other atom), I know that an electron can transition from one energy level to another, either by absorbing or releasing a photon of a precise hf. How much time does an electron take to make a transition from one energy level...

I was taught that a particle is assigned to a unique quantum state. As a specific example, two bound electrons can't have the same quantum numbers in an atom. And likewise one and only bound electron is assigned to one quantum state in an atom. Yet, I am reading several solid state books and...

I'm working on a problem with a Harmonic oscillator which suddenly goes from the frequency ω_a to ω_b and I'm trying to find the expansion coefficients in |0 \rangle _a = \sum_{n = 0}^\infty \alpha_n |n\rangle _b where |0>_a is the ground state right before the change in frequency. The...

If one has already known the dispersion dataset, for example, for 2D crystal, we know the 1000*2000 dataset for E=E(k_x,k_y), How to find the density of states numerically?

I always thought they were the same, but now I am reading a question that says "which of he following time-independent functions describe stationary states of the corresponding quantum systems?" Is there something I am missing? It's written like there is something to solve, but to me it seems...

I have a classic infinite, linear chain of atoms, each of mass m, each separated by a spring with spring constant b and equilibrium distance a between each adjacent one. I know from my textbook that the dispersion relationship you get for this is: \Omega(k) = 2\sqrt{\frac{b}{m}} |sin(ka/2)|...

When we speak about wave function of an electron, we write it as ψ_{n,σ} (x,ζ) so that we specify here the orbital quantum number by n and spin quantum number by σ. σ can take two values according to spin up or down. x is space position and ζ has two discrete values related to spin up and down...

While studying about k-points, etc. I came across the terms density of states. What is it's physical meaning. research papers often have DOS graphs in which they segregate s, p, d contributions and talk about fermi level etc. Is this DOS the same as the kohn-sham orbitals that are solved for in...

Hi everyone, I've hit a bit of a snag with part c of this problem (can't figure out how to invert a function T(ν)), so I'm starting to question whether I have the previous parts correct. Homework Statement Consider a system of N identical but distinguishable particles, each of which has a...

Why must it be true that a system that has a bound state must have its scattering amplitude have a pole in the upper half of the complex wave-number plane? For example, if the scattering amplitude as a function of the initial wave number magnitude |k| is: A=\frac{1}{|k|-iB} with B>0, then...

Hi, Just a little thing that's been puzzling me: Consider a state \mid \psi \rangle = \frac{1}{\sqrt{2}} \mid A \rangle + \frac{1}{\sqrt{2}} \mid B \rangle This is normalised since [\frac{1}{\sqrt{2}}]^2 + [\frac{1}{\sqrt{2}}]^2 = 1 Now let A = B: \mid \psi \rangle =...

Homework Statement A hydrogen atom in an excited state absorbs a photon of wavelength 434 nm. What were the initial and final states of the hydrogen atom? Homework Equations 1/λ=1/91.127 * (1/nf2-1/ni2) The Attempt at a Solution Tried to use the equation, but keeping the initial...

Homework Statement I must prove that the set of coherent states \left\{ \left| \lambda \right\rangle \right\} of the quantum simple harmonic oscillator (SHO) is a complete set, i.e. it forms a basis for the Hilbert space of the SHO. Homework Equations The coherent states are defined as...

Just an idea: is there an index theorem for an n-dimensional Hamiltonian H = -\triangle^{(n)} + V(x) which "counts" the bound states (H - E) \,u_E(x) = 0 i.e. eigenfunctions and eigenvalues in the discrete spectrum of H?

I am aware and well read on the decoherence approach to understanding how conglomerations of micro quantum systems will tend to lose quantum coherence via interaction with the environment. The cross terms in the density matrix for the system will tend to zero (due to the partial trace...

Homework Statement This is something I should know, but I keep getting mixed up when I try to think about it. A quantum state can be written as a superposition of basis states such as \left | n \right \rangle So let's say I have a particle in a potential with discrete energy levels...

I am confused about mixed quantum states, if the only observable states are pure eigenstates, since we have to measure to observe, what is the physical meaning of a mixed state?

I was reading Mandle QFT book, and it says: "If we require the vacuum states to be invariant under Lorentz transformations and under translations, then this field must be a scalar field, $\phi(x)$, and its vacuum expectation value must be constant". Could anybody explain to me why is that?

My calculus textbook says the populations of each of the fifty states is a vector quantity. I know what a vector is but I'm not grasping this particular example. Any help? I would think that maybe it's because the populations may increase or decrease but I thought a vector quantity was...

Homework Statement Determine the total number of energy states in silicon from the edge of the conduction band to Ec + kT for T = 300K. Homework Equations N = \intg(E)dE The Attempt at a Solution I'm pretty sure I know how to do this one. The only problem is, when I get to the...

Homework Statement Given state: |ψ> = |0> + α|1> + σ^2/√2 |2> find the wavefunctions. I am confused between states and wavefunctions, everywhere I've read it says that state (ie the wavefuctions), really need some enlightenment here..

How I am supposed to explain why with three forces on a force table there is only one equilibrium state. Also I need to explain the reasons for when there are four forces on the force table it is possible to have two equilibrium states. And if it is possible to have more than 2. I think my...

For my Java programming course, I have been asked to create a class called Parliament & describe its key states and behaviours. I know that key states describe what an object is and behaviours describe what an object does. I've also been advised to base an object's state and behaviour by picking...

so all my american books have that label (i live in Europe) what content could possible be different between these two versions, i know you use the metric system for science just like us...is it that you keep all the juicy secrets in the us version??

So my initial question was whether or not light was considered matter. While googling this question, I came across this answer: http://answers.yahoo.com/question/index?qid=20080717210504AAngJQO In the top answer given, it is inferred that photons (light) are included in the definition of...

1) What is adiabatic availability? 2) How can the state of a system change without changing amounts of constituents or without changing parameters? 3) Does anyone really use the concept of "adiabatic availability" other than Gyftoppoulas and Paolo? I am reading the book, "Thermodynamics...

Homework Statement It's easier to post a picture of the problem: Homework Equations In picture, and boson occupation number: \left\langle n_k \right\rangle = \frac{1}{e^{\beta E(k)} - 1} Where E is the energy of the state with k and \beta = 1/k_B T The Attempt at a Solution Goal: Find...

I was reading this article, http://www.nature.com/news/2009/090122/full/news.2009.50.html, and it was talking about how they 'teleported' a Ytterbium ion (Yb+) and mid-way through the article it said that they had to destroy the quantum state of the original Ytterbium ion and they did that by...

Homework Statement Let q be a mixed state which we mix from pure states. What are the weights we must take for the pure states, respectively? Let us start the solution with the two-state system. The Attempt at a Solution My problem is I can't decypher what the problem actually is, from...

Homework Statement the first two energy eigenstates of a 1 nm wide finite well of barrier height 8vo have energy eigen values of 0.66ε and 2.6ε. calculate the expectation value of a linear superposition of these states? Homework Equations airy equations The Attempt at a Solution...

Water at 0°C was placed in a dish inside a vessel maintained at low pressure by a vacuum pump. After a quantiti of water had evaporated, the remainder froze. If 9.31 g of ice at 0°C was obtained, how much liquid water must have evaporated? The heat of fusion of water is 6.01 kJ/mol and its heat...

speaking of solid, liquid, gas, and plasma, where in nature do these four states of matter interact to form a discrete system? the only example i know of, with my limited knowledge, is sun (plasma), Earth (solid), sea (liquid), and sky (gas) ... all work together to form something like a...

Could somebody point me in the right direction on how to go about starting this question please? In need of some guidance on where to begin. Homework Statement Calculate the separation between the two lowest energy states for an electron confined in an infinite potential well of width 1nm...