States Definition and 1000 Threads

We've solved for several systems, the hydrogen atom for instance, and one of the properties of these is that it doesn't matter what excitation state you look at, they are stationary states, the Hamiltonian is constant in time, so where's the impetus on an excited atom to radiate light if it's in...

Homework Statement I know how to derive the density of states for an ideal gas by using the energy equation: E_n = A*n^2, where A = (h_bar^2*pi^2)/(2mL^2) but what about for a 'photon gas'? Do I use the same energy equation as above, or the following: E_n = (h_bar*pi*c/L)*n...

Hello, So is there any software, that generates the differential equation for the input circuit? I am trying to solve a problem and I want to check if my equation is right. Thanks.

Homework Statement Determine how many terms of the following convergent series must be summed to be sure that the remainder is less than 10^-5. Although you do not need it, the exact value of the series is given. ln(128) = 7*sum[k=1,inf] of (-1)^(k+1)/k Homework Equations [b]3...

Homework Statement 1. Find the density of orbitals (often called 'density of states') for a free electron gas in one dimension, in a box of length L. 2. Find the density of orbitals for a free electron gas in two dimensions, in a box with area A. Compare with the three dimensional case...

How to calculate number of quantumstaes or unit cells within energy range E and E+dE in the phase space to prove the eqn: g(E)dE=[(8π√2V)/h^3]*m^(3/2)√EdE

So the problem is following. The density of states in energy space (3D case) represents the number of states per unit volume per energy. This means that the unit is #(number of states)/(cm^3 eV). This result can be seen in many solid-state physics books. I am reading some articles where the...

Hi, This is probably trivial, but I don't see it and would therefore appreciate receving inputs. Suppose we define a state |\phi_{lr}\rangle = \sum_{n=0}^{N/r - 1}\sqrt{\frac{r}{N}}|l + n r\rangle How is the quantum Fourier transform of this state equal to...

Can one go about creating excited states of a nucleus without using neutrons? For example, Aluminium 26 exists in a ground state that has a half-life of about 70000 years, and decays by beta particle emission. It can also exist in an excited state that decays with a half-life of about 6.3...

Homework Statement The relative population of two atomic population states in equilibrium is given by Boltzmann Distribution: n1/n0 (proportional to) e^(-ε/(κT)) , where ε is the energy difference between the two states, T is the temperature and κ is the Boltzmann constant = (1.38 x...

I’m having a little difficulty understanding the difference between pure states and mixed states. Given a physical system and its associated Hilbert Space, is each member (or ray) of the Hilbert Space always a pure state? Is every linear combination (sum or integral) of pure states in the...

Let's say I have an equation E=iE0cos(kz-wt)-jE0cos(kz-wt), how do I look at this and know, this is linearly polarized? or what if it changes and the kz is negative? or its a sin function with with (wt-kz-pi/4) in it. I just don't understand what this equation is supposed to be telling me and...

I've never heard of any excited states of the proton. Why? By "excited state" I mean something with the same composition (uud) that decays to the proton (plus photons etc.) with nearly 100% branching ratio.

Hi. Coherent states of light, which correspond to classical em wave, are eigenstates of non-Hermite annihilation operator. Fock states are eigenstates of Hermite number operator. Are Fock states are expressed by combination of coherent states? If yes, how? Thank you in advance. ref...

One of the postulates of quantum mechanics, as quoted in any textbook on the subject, is something like the following: "states are vectors in a Hilbert space." But then they go on to solve the problem of the free particle, which should (I guess) be about the simplest problem one can solve...

Suppose we have a photon whose polarization state is unknown, what measurement can be done to determine the state of that photon? How many times are we supposed to make the measurement in order to confirm our results? How can we distinguish a mixed state to a pure state?

Hello everybody I am currently trying to understand attempts to create a framework of generalized probabilistic theories in which quantum theory and classical theory appear as special cases. More precisely, I try to understand the framework which is sometimes called the framework of "convex...

The nucleus of an atom has discrete energy states. And most of the time it emits gamma rays and x-rays from the nucleus. If I pack enough atoms into a solid or some other configuration could I get the nucleus to emit visible light. Is there any way I could manipulate the states to get them to...

this wikipedia article http://en.wikipedia.org/wiki/Qubit says i am kind of comfortable with the physics of it, but i am totally lost on the thing about vector space over the complex numbers can someone please lend me a hand? it seems that the more i try to read about it, the less i know

Homework Statement In lecture for stats and thermal, we briefly talked about quantum states and went through an example. However, the lecturer simply told us the answer to the second part of the question without going through it. Here's the question: 1a.) How many molecules of H2O are in...

Homework Statement The figure (see attachment) shows part of a energy-state-diagram for an atom. Three energy states are included. At energy transition 1 & 2 the atom emit radiation with the wavelengths of 2.56 \cdot 10^{-8} m and 3.04 \cdot 10^{-8} m, respectively. Find the wavelength...

From Ryder: "We can now see how a supermultiplet of ten baryons may arise. Baryons are made of three identical fermions, so the possible states may be classified according to their symmetry under interchange of quark labels. Altogether there are 27 states. One of these is totally...

I am reading an introduction to quantum computing and I have a question about one thing I don't understand. "In classical physics, the possible states of a system of n particles, whose individual states can be described by a vector in a two dimensional vector space, form a vector space of 2*n...

Say you have a free particle, non relativistic, and you want to calculate the density of states (number of states with energy E-E+dE). In doing that, textbooks apply periodic boundary conditions (PBC) in a box of length L, and they get L to infinity, and in this way the states become countable...

Hi, I'm studying statistical mechanics from Reif's book. In his book Reif is reaching the conclusion that the number of states avaiable to a system at energy E (up to some small uncertainty in the energy due to finite observation) with f degrees of freedom is proportional to E^f . There is...

Homework Statement I am trying to retake an old course in statistical mechanics but run into integrals that i simply have forgotten how to solve. Given an denstiry of states such that f(\epsilon)= \frac{1}{|\epsilon |} for \epsilon_{min} \leq \epsilon < 0 and 0 elsewhere Using the mean...

I'm brushing up on squeezed coherent state and have seen them defined in terms of position and momentum squeezing and in terms of amplitude and phase squeezing...is there a relation between the two? Am i missing something obvious :p ?

With constant talks about cutting spending with respect to scientific research in the United States do any of you feel that looking for work outside of the U.S. is the best option? Especially if let's say a tea party candidate were to win the presidency in 2012 or 2016. I'm still an...

http://www.sciencedaily.com/releases/2011/03/110331104014.htm ScienceDaily (Mar. 31, 2011) — Do the principles of quantum mechanics apply to biological systems? Until now, says Prof. Ron Naaman of the Institute's Chemical Physics Department (Faculty of Chemistry), both biologists and physicists...

Many economists are predicting that America will get downgraded from AAA by at least one agency regardless if congress raises the debt limit. There has already been a great deal of damage caused from the political posturing in Washington. If the central government's debt gets marked down, I...

Title may sound weird,but I think it might be worth exploring In axiomatic formulation of quantum mechanics, quantum states are postulated as vectors residing in Hilbert space. The only apriori requirement that Iam aware of ,for a quantity to qualify as a quantum state, is that it should...

Hello, I am a beginner on the sbject so please correct if I'm using some sloppy terminology. I'll try to be clear. Consider a Hamiltonian with degenerate energy eigenstates (say the degeneracy is on angular momentum as in hydrogen atom). Which of the degenerate eigenstates would the wave...

hello friends, Many of my friends tell me that there are 7 states of matter.Could anyone explain the 6th and 7th for me?

Hi. In the book I'm reading I've come to a question regarding degenerate states in one dimension. It says that in one dimension there are no degenerate bound states. But say I have a stationary state with some energy E, and assume that it is normalizable. You can easily show that the complex...

I am an Engineering Physics (specifically nuclear) student at McMaster University. I was poking around at some postings in the industry and I noticed that a lot of the American job postings say that you need to be a US citizen and have security clearance. What I'm wondering is, does this apply...

Hi everyone, I am working through Ballentine's Quantum Mechanics books, and I am stuck... I would be appreciative if someone could walk me through this section with some help. Here is my first confusion. In this case then |a_{m'}b_{n'}\rangle\langle a_{m'}b_{n'}| do not form a complete...

I happen to be studying the basics of quantum mechanics at the moment and have made acquaintance with the vector representation of quantum states, in particular the two states of electron spin. For this question let's just say the spin can be up or down. The state of the spin is...

Let X be a Markov chain with a state s that is absorbing, i.e. pss(1) = 1. All other states communicate with s i.e. i → s for all states i ∈ S. Show that all states in S except s are transient. I understand this intuitively, but I'm not really sure how to start the proof.

Is a living macro object, such as a cat or human being, in fact in a superposition of states? (I am thinking about for instance the multiple-universe idea)

So in Griffith's (ed. 2 page 37) there's an equation that says that **pretend the h's are h-bars...I don't know Latex very well** ih\frac{1}{\varphi}\frac{d\varphi}{dt}=-\frac{h^{2}}{2m}\frac{1}{\psi}\frac{d^{2}\psi}{dx^{2}}+V Since in this simplified case V where is a function of x alone...

understanding 1. single photon and 2. entanglement ...states a photon spin is not know till we measure it. once we measure it we get some value (L or R, V or H etc)? does this value change if we were to measure it again after a few seconds? (assuming no interaction in-between)? now we move...

Hi all. Here is an n-particle hamltonian. H=\int d^{3}xa^{\dagger}(x)\Bigl(-\frac{\hbar^{2}}{2m}\nabla^{2}+U(x)\Bigr)a(x)+\int d^{3}xd^{3}yV(x-y)a^{\dagger}(x)a^{\dagger}(y)a(x)a(y) Here is an n-particle state. \Bigr|\psi,t\Bigl\rangle=\int...

can somebody simply explain what is meant by NEGATIVE QUANTUM STATES , as given by dirac in his theory?i know its not as SIMPLE as i want it to be , but still I would like to know its significance in the most basic way!

Hi, could someone explain the following quote to me, please? It explains, why the Kohn-Sham-Scheme of DFT fails to describe transition states. My questions: If N_i ist the occupation number and the wavefunction may be given by \Psi = \sum_I{c_I \Phi_I} where \Phi_I are...

I'm confused about what is going on theoretically with Raman, and light in general, wrt photon absorption, annihilation, and re-emission; I don't have the math background to understand Fourier transform, of anything past simple algebra anymore, but would like to at least have a decent...

Hi I have currently read about dressed states, but I don't get what it is. Does it have something to do with AC-Stark splitting? Hope someone can give me a nice explanation :-) Thanks

What are interaction states and what are mass states? Which ones are physical states? Which ones appear in Feynman diagrams? Explain your answer. I have that an interaction state is the state of a particle before the Higgs mechanism and the mass state is after the Higgs mechanism has given...

I'm trying to get my head around the step function and the energy states of the quantum well. What I've got so far is this: The density of states for an electron confined in one direction by the potential barriers of the well, but free to move in the other two directions in the place of the...

Hi everybody... I have two questions about what I couldn't understand in quantum physics: 1- could anyone tell me please what is different between wavefunctions, eigenfunctions and eigen states? 2- what is different between Operator and eigenvalue? thanks a lot

Homework Statement Calculate the average number of electrons (the occupation probability) in a localized state of impurity in a semiconductor at a finite temperature T. The impurity state in a semiconductor can be empty or it can be occupied by only one electron. The Attempt at a Solution...