States Definition and 1000 Threads

Hi, I'm taking an introductory course on solid state physics next semester, and the book the Professor has chosen is the 8th edition of Kittel. I have heard MANY bad things about this book, so I'm wondering if I should just use an earlier edition or another book entirely. Any...

Hi. I would appreciate if some one could help me with my question. But first some background: There is a classical problem of inverted pendulum under control. Pendulum can be put to UNSTABLE equlibrium and (if no control applied) it can put itself to STABLE equlibrium. So system under...

What is the meaning of "electron states"? I was seeing the energy level diagram of a semiconductor. I came across this term "no of electron states" along the x-axis. I couldn't understand the meaning of that. The diagram was similar to this-...

The ground state for two identical fermions in a box (in 1D) is given by: \psi (x_{1},x_{2})_{12} = \frac{\sqrt{2}}{a}[sin(\pi x_{1}/a)sin(2\pi x_{2}/a) - sin(2\pi x_{1}/a)sin(\pi x_{2}/a)] The book I'm reading though says that this state is non degenerate, and that the next excited state...

Hello everyone, I was reading Ashos Das book on field theory, chapter 4.3, and I had this question. This expression: \begin{equation} \left< \psi_f | \psi_i \right> \end{equation} is the transition amplitude of two states. This expression: \begin{equation} \frac{ \left<...

I am the point where i need to learn about Density of states, how to explain the concept and how to then calculate it for different systems, however I am unable to find any texts that really explain it on an introductory level. If anyone knows any sources or text that have a good introductory...

So far, we've discovered this compositeness hierarchy: Atoms - bound states of electrons, nuclei, photons Nuclei - bound states of nucleons and other hadrons Hadrons - bound states of quarks and gluons So are any Standard-Model particles bound states of any other particles? The...

So, in QM making a measurement collapses the state into an eigenstate of that observable. Thus, if the system is properly isolated, then the same measurement should return the same value. But the eigenvalue for that state is degenerate, then does that mean the state might actually collapse to a...

examples of substances (elements or compounds) that sink in their liquid states. (solid state is denser than liquid state compared to water) :smile:

Hi there, I am reading several books on quantum mechanics and they mention some concepts on coherently and incoherently superpose a bunch of wave functions. As my understanding, if there are series of wave functions, which satisfying a certain distribution, the coherent way to calculate the...

If we consider two laser beams with identical 3 level energy level schemes except that the metastable state for one has a lifetime of 1μs and the other, 100μs. Which will give the brighter (more intense) beam? I gather that, since all things are identical up to the metastable state, the...

I've thought about dark matter and I'm wondering if it could possible be made up invisible bouond states of ordinary matter? Wikipedia says "According to consensus among cosmologists, dark matter is composed primarily of a new, not yet characterized, type of subatomic particle." But why a...

I wonder whether an electron can make a transition from one metastable state to an another metastable state, if so it leads to a paradox(atleast according to me) viz for the refrence frame of the metastable state A from which electron makes the transition, it will be a radiative transition and...

Would more people use marijuana? Would some people start using more frequently? Would prices go up or down? I don't know the answers. I think there would be some people who would now start using without worry of the law. However, there would also be some people who now view it as far...

Homework Statement Consider a gas of non interacting electrons in two dimensions with electronic density n by unit of area and mass m. The gas forms a square of sides L. 1)Assume periodic boundary conditions, find the density of states by unit of area. 2)Find the Fermi energy in function of...

Hi, All articles on spin liquids I've seen treat them as insulators. This is understandable in the context in which they were first introduced i.e. the resonating valence bond state in which every electron is singlet-ed with every other, and thus essentially blocking conduction. Given...

When you consider a electron L×L×L box, I think I understand how to derive the DOS-spectrum. Unfortunately, when a small change is made to the problem, I really don't understand what to do, so I probably don't understand the theory at all.. This is the question: Homework Statement Consider a...

When electrplating copper with a dilute NaCl aqueous solution and the anode is iron while cathode is platinum what will the results be? Will copper form cations or will the OH- be oxidised? Also, if we use concentrated NaCl will there be any difference? I'm thinking that the copper shouldn't be...

In measuring the x component of angular momentum of a state, by using the expectation value calculation of Lx, i got i/3 h bar - i/3 h bar, does this means that the probability of h bar is i/3 and the probability of 0 h bar is 0 and the probability of -h bar is i/3? If so, when is the...

The variation method for approximating the the ground state eigenvalue, when applied to higher energy states requires that the trial function be orthogonal to the lower energy eigenfunctions.In that respect this book I am referring(by Leonard Schiff) mentions the following function as the...

http://dl.dropbox.com/u/33103477/harvesting.png So am I right in saying the 2 steady states are: N_1=\frac{h}{r}, N_2=\frac{1-h}{\alpha} Now plugging in N_1 into the equation I get: \frac{-h^2 \alpha}{r} < 0 So N_1 is stable. But I can't quite figure out how to classify...

Consider waves in a box. It is customary to calculate the density of states either by enforcing vanishing boundary conditions, then the wave numbers are k=\frac{n\pi}{L} and we take only positive k, or using periodic boundary conditions, in which case k=\frac{2n\pi}{L} and taking all wave...

There are a lot of coherent definitions of Hilbert spaces. Let's take the wikipedia one and let me ask you some cuestions: A Hilbert space: 1) Should be linear 2) Should have an inner product (the bra - ket rule to get an amplitude) 3) Should be complete (every cauchy sequence should be...

Homework Statement We have N non interacting particles in external field \vec{H}. The hamiltonian is given as H = -h\sum^{N}_{i=1}{\sigma_{i}} with \sigma =\pm 1 and h = - \mu |\vec{H}|. Calculate the number of states with given energy E with help of this relation: \Omega =...

Homework Statement density of states of photon gas is proportional to ... (a)E^1/2 (b)E (c)E^3/2 (d)E^2 Homework Equations i know the relation for density of states of electrons which is proportional to E^1/2. So far i was thinking that electrons and photons shares the same...

I want to know if a quantum computing model exists where you can prepare two different states on n qubits and interfere (i.e. add) them together. For example, for two qubits, consider the states (|00> + |01>)/√2 and -(|00> + |10>)/√2 (both pretty easy to prepare in most quantum computing...

Homework Statement Part of a past paper, I can do all of the question a-d without problems but the second part of e) is giving me trouble. So you have the following state \frac{1}{\sqrt{2}}(\mid 0 \rangle_{A} + \mid 1 \rangle_{A})\mid 0 \rangle_{B}\mid 0 \rangle_{C} You apply a...

Hi all, I've recently been reading about the Unruh effect, and there are a few things that I'm not very clear on: 1) An accelerating observer will see a vacuum filled with particles in thermal equilibrium (a warm gas) where an inertial observer would see zone. I'd originally read that...

Hi there, I know in this article - http://arxiv.org/ftp/arxiv/papers/1203/1203.4834.pdf - the authors discard the clicks at H at output b" with V at output c" (and vice versa), saying they are seperable states regardless of whether the decision to perform a bell-state measurement on photons #2...

Homework Statement I'm having a hard time trying to figure out where to start. I know I have to assume the diode states and then calculate if the assumptions work within the circuit. The Attempt at a Solution None as yet because I'm never sure where to start on these circuits...

Homework Statement how many possible quantum states for a nitrogen atom with electronic configuration of 1s22s22p3 Homework Equations ? The Attempt at a Solution So, the answer for this question is 20, but I can't for the life of me find out how. The book we're given is...

Can anyone help me find out how to work out how many different quantum states are there in the Hydrogen atom with principal quantum number n = 6 and orbital quantum number l = 1? Any help?

http://dl.dropbox.com/u/33103477/model.png Form of the equation \gamma -\delta p_t = \frac{p_{t-1}-\alpha}{\beta} or p_t = \frac{-1}{\delta \beta}p_{t-1} + \frac{\alpha + \gamma \beta}{\delta \beta} So the steady state is p^* = \frac{\alpha + \gamma \beta}{\delta \beta + 1}...

Does the proton have n-pole excited states? Or n-pole excited states exist only for A>1?

Hi, Suppose I have a 2D spinless electron bounded by a parabolic confining potential. If we add a magnetic field perpendicular to the plane the eigenstates of the system are the so called Fock-Darwin states. However, suppose we change the boundary potential to a circular hard-wall potential...

Cubic Population Model with steady states ! I am unsure as what this question means: Consider the cubic population model: dN/dt = cN(N-k)(1-N) where c>0 and 0<k<1 If the the initial populations is N_0 describe without proof the future of the population, distinguish the various cases on...

Homework Statement Consider a system made of 4 quantum fermions that can access 10 distinct states respectively with energies: En=n/10 eV with n=1,2,3,4,5,6,7,8,9,10 1) Write the expression for the entropy when the particles can access all states with equal probability 2) Compute...

When metals such as sodium react with an acid, a salt and hydrogen gas is produced. and we know for sure the oxidation state of sodium in the compound will be +1. But for other metals such as iron, when they rest with acids which oxidation state do I use? I'm unsure if I'm supposed to use the...

In a semiconductor @ 0k highest energy state lie on fermilevel(all electrons @ valence band). but @ room temperature highest energy state of covelence band lie below the fermilevel. how can i understand this? pls help me.

Hey everyone, so I recently watched a vid that talked about Googol and googolplex sized universes, and their implications quantum mechanically. Supposedly, the number of quantum states that the particles that make up our body can make is something like 10^10^70. The physicist then said...

I am doing my thesis in quantum information and I am learning the background of it, I met this two things mixed and pure states. I have read a few books and a few articles too. But I still can not get the idea. So If anyone can give some help explaining this, would be such a good help. Either if...

I saw this today, thought some of you might find it interesting (as I did). Product states do not violate Bell inequalities. Entangled states do, and this draws a clear line between the quantum world and the classical world. So imagine my surprise with this: a paper that shows that even...

What is the theory behind dividing human society into Countries and States? Do the taxes collected from people on a state are meant to be spend for the welfare of the State alone or we sometimes spend the money to help other 'poorly doing' states? In a more general perspective, are we trying...

Homework Statement I've been asked to find out if are entangled states or not Homework Equations I thought an entangled state was one where a measurement of one qubit revealed the nature of the other qubit in the state The Attempt at a Solution If I am correct in my definition of an...

I am completely lost with this question... for example for 2 electrons coupling that results in a singlet state with a spin momentum of 0 or a triplet state with spin momentum √2h-bar. How would you go to find the geometry of these states?

Hey guys, I'm an engineering PhD student, and I'm doing some work with laser-induced fluorescence. At the moment, I'm trying to understand some notation about the excited states of nitrogen dioxide. One of the papers I'm looking at, V.M. Donnelly, et al. J. Chem. Phys. 71, 659 (1979), is saying...

Ok, I am having some trouble with the maths regarding Bohr Theory. I understand that the orbit radius is r=n^2xa0 where a0=0.0529 and that the wavelength for an electron with l=0 (circular orbit), is λ=2∏r so for n=1, λ=6.28a0. So, following the same maths, for n=2, I get...

Question about Landau: Definition of "Number of states with energy" in an interval Hey! I am currently reading Landau's Statistical Physics Part 1, and in Paragraph 7 ("Entropy") I am struggling with a definition. Right before Equation (7.1) he gives the "required number of states with...

Hi, it's been awhile since taking a quantum mechanics course, but I thought I read somewhere that during an electron decay into a lower stationary state, it can be shown to literally oscillate between the states momentarily, hence providing a clear source of acceleration in a kind of oscillator...

Dear all, My aim is to get the density of states (DOS) per unit area for monolayer (bilayer) graphene. I have done this using mathematica. I have set a sampling k grid with 22500 points and computed the expression: DOS=(1/Nk)*Ʃ δ(E-Ek) where the sum is over the k points in the reciprocal...