States Definition and 1000 Threads

I've been looking at interactions between K mesons and "ordinary" matter such as protons and neutrons. Since I can't put a bar over a letter, I'll let a CAPITAL letter stand for an ANTI-quark. sD + duu ---> suu + uU (thru a resonance baryon suu ++) I know this one is possible, but what...

I am doing some research on Bose-Einstein condensates and was hoping someone could give me a non-mathematical reason as to why bosons 'want' to occupy the same ground state. I think its details come from Bose-statistics, but is there a simplified way of explaining it? Thanks

Homework Statement I'm having a dumb moment in proving why the following is true: D(k)d3k=\frac{V}{4\pi^{3}}4\pi k^{2}dk Homework Equations NA The Attempt at a Solution I realize that the second part 4\pi k^{2}dk is an integration element d3k. But the density of states I can't...

Hi, the wikipedia article on fermium states that it is the last element that can be synthesized by neutron bombardment but decides not to explain why. Can anybody give a layman's explanation? Thanks.

Hi there, mathematician learning a little QM here. I've been watching a few of these lectures: http://www.youtube.com/watch?v=LBFBQr_xKEM&feature=relmfu The lectures are good, a little slow paced for me, but clear at least. He starts talking about polarisation in the last half of...

I have seen thee following relation in regards to free electron waves with wavevector k : < k | k' > = (2.pi)^3 . d( k - k') where d() is a Dirac delta function. Why the 2.pi factor?? I can't seem to motivate it. Also, from this, it is stated that the density of states is then 1 /...

This fascinating question was asked by our favourite blogger at http://physics.stackexchange.com/questions/5517/dual-conformal-symmetry-and-spin-networks-in-abjm .

Hello, I am trying to express a given wavefunction through different basis, momentum and position. Look at 5.2(b) and (c) through the link: http://qis.ucalgary.ca/quantech/443/2011/homework_five.pdf" I complete part (b) by doing the following...

Hi, I would like to ask some questions in regards to preparing mixed states. Assuming I am allowed to prepary any pure quantum state, perform measurements and apply unitaries, I am asked to prepare a single qubit quantum state of maximum entropy. As I understand, a 1-qubit quantum...

Please teach me this: In QTF theory book,I have not seen what saying about probability of creating or anihilating particle(quantum).So I wonder whether we can apply superposition principle for the states with different numbers of particles in Fock space. Thank you in advanced.

Could anyone give me a good reference for construction of asymptotic states in QFT. Usually one assumes that long before and long after collision particles almost don't interact because they're spatially separated. This statement is based on the assumption that particles might be represented as...

Is there a defined change in the electron orbitals of atoms as they transition from one state to the next? Is there a connection between the average kinetic energy of an atom, its electronic structure and its state of matter?

Hi I am reading something, and came across pure/mixed states. Considering that mixed states do not have the coherence terms (off-diagonal terms) in the density matrix, there seems to be a deep connection between mixed states and a classical system. This is also emphasized by the fact that a...

As I understand it, the Pauli exclusion principle states that no two like fermions can be in identical quantum states. I also understand that the quantum states are thus: n, which is the electron shell, l, which is the subshell, m_{l}, which is orbital, and m_{s}, which is spin. However, it...

I need to calculate the density of states for a dispersion relation which is like the free electron dispersion, but with one effective mass in the kx, ky directions, and a different effective mass in kz. So I need to integrate the inverse gradient of E(k) over a surface of constant energy, ie...

In the following article http://books.google.com/books?id=u1DJomI318MC&pg=PA76&lpg=PA76&dq=swallow+goldstone+particle&source=bl&ots=2JysrTHS0c&sig=Qq8r6Cw0zSVD38Vfses5BxGX9UQ&hl=en&ei=1M51Tc3hLse6hAeaxJSJBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBMQ6AEwAA#v=onepage&q&f=false it...

After a fruitless search for a good undergraduate resource for Green's Functions (Economou's book is far too advanced for an intro course) , I hope someone here can clear this up. So I have the Greens Functions (gf) for the time independent Schrodinger equation: SUM |a><a| / (E - e(k))...

Take water for instance. It has a little vapor in liquid state. Today our professor explained boiling points and freezing points, but didn't go to molecular level, he only said that it needs more energy to actually boil water, or freeze it. Can u explain why more energy is needed to add to water...

Homework Statement The last 2 parts of the attached photo. (4 and 6 marks) Im really not sure how to go about them in a (clever) way that won't take 2 hours. Homework Equations Possibly the fact that the product of the raising/lowering operators, J-J+ = J2x + J2y Answers to previous...

Homework Statement A pion is a spin-0 particle with a negative unit charge. A neutron is a spin-1/2 particle with no charge. A proton is a spin-1/2 particle with positive unit charge. One can construct an unstable version of the hydrogen atom where the nucleus contains both a proton and a...

Homework Statement dJ(x,t)/dx = -dY^2 / dt , where y is the wave equation, and the d's represent partial derivatives. I want to make an assumption that I can describe the wave equation as a stationary state, so my question is the following: What is the definition of a stationary state...

Homework Statement calculate the possible number of ways of distributing 2 particles among four energy startes when: particle are distinguishable and there is no restriction on the occupancy of the energy state Homework Equations \frac{(n+g-1)}{n!(g-1)!} The Attempt at a...

I had been reading several articles on topological insulators (TI) including the Kane and Hasan's 2010 RMP. I am not very much clear about the Z_2 invariant TI. I mean, the even-odd argument proposed by Kane and Male (also argued by S. C. Zhang's group and Joel Moore's group in a different way)...

hi All, why is this? some matter has a refractive index of slightly less than one for light in the x ray region. This implies a phase velocity faster than c, right? could someone explain what is actually happening here? THANKS!

Homework Statement The unperturbed Hamiltonian H0 of two independent one-dimensional operators is H_0=a^{\dagger}a+2b^{\dagger}b where a and b are operators such that [a,a^{\dagger}]=1=[b,b^{\dagger}] Find the degeneracies of the eigenvalues of H0 with energies E0 = 0, 1, 2, 3, 4...

Hello, I am trying to decompose |(pi/2)+\vartheta> into canonical basis. I have done it for |\vartheta> but i am unsure about what to do with the pi/2. Given |theta> = (cos\vartheta sin\vartheta) I was thinking that pi/2 becomes (0 i) and I would add the two vectors together. Any help would...

How did they "note" this from (16)? http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20110122_121814.jpg?t=1295721126

Effective theory of bound states from QCD?? Do you know any work that actually succeeds in producing the action of an effective field theory for nucleons and mesons, starting from the QCD action?

Homework Statement The vector |p> is given by the function x+2x2 and the operator A = 1/x * d/dx, with x = [0,1]. a) Compute the norm of |p> b) Compute A|p>. Does A|p> belong to the VS of all real valued, continuous functions on the interval x = [0,1]? c) Find the eigenvalues and...

Hello I have come across this inexplicable fact mentioned in somewhere that for a chain of S = 1 spins, the adjacent bonds can all be in a singlet state i.e. singlets can be shared in this case (forming valence bond solids) but not, for example, for |S| = 1/2, the latter point being clear. I...

Let's consider self-interacting scalar field described by action: S = \int d^4 x \frac{1}{2} \left[ \partial_\mu \phi \partial^\mu \phi - m^2 \phi^2 - \frac{\lambda}{4!}\phi^4\right] Using relation between Poisson bracket in classical mechanics and comutators of quantum operators we...

Hi there, I have a passing interaction with quantum dots and light emitting polymers as part of my research. I've been reading up on the physics of qdots and polymers recently. One thing that strikes me is that the existence of triplet states in polymers is mentioned, but not in quantum dots...

Hi there, I'm a bit confused as to the meaning of the following figure, for the quantum well case: I understand that with the quantum dot, since the states are completely quantised you get the delta functions - states only exist at certain energies so the DOS at these energies is non zero...

On one side I have [state1] a nut and a bolt, side by side. On the other side, [state2] a nut fastened over a bolt. What is the difference between these two matter concentrations? Of course, some energy has to be spent to fasten the nut. But it is not the process and the energy to bring about...

Hi! I always wonder, why "Time Travel" equation make use of velocity of an object ( speed of light etc.) Why not it is related to the state of objects constituting the universe. Say, in my tiny imaginary universe, that just consists of me and a road from point A to B. A...

I wonder whether Dirac explanation of paradox of negative energy solutions of his equation is viable. Of course this paradox is absent in QFT but if we treat Dirac equation as an equation for wave function of electron the negative energy solution are a puzzle. Acording to Dirac we don't...

Dear Physics Forums, I have a reaction scheme with 4 states where A<->B, B<->C and B<->D: C / A - B \ D This proceeds to equilibrium from a start point of A = 1 and B, C, D = 0. Forward and reverse rate constants for A<->B are K(1) and K(-1), for BC...

Homework Statement I'm having a little bit of trouble getting started with this problem. Can I get a little help? Using: (number of states in the six-dimensional region d^{3}x d^{3}3p) = (d^{3}x d^{3}p)/h^{3} Which provides a convenient route to the single-particle density of masses. a)...

Homework Statement Given that a^+|n\rangle=\sqrt{n+1}|n+1\rangle a|n\rangle=\sqrt{n}|n-1\rangle and that the other eigenstates |n> are given by |n\rangle=\frac{(a^+)^n}{\sqrt{n!}}|0\rangle where |0> is the lowest eigenstate. Define for each complex number z the coherent state...

Hello! I have a very simple question... Does anyone know if exists on the WWW a database where I can download the calculated density of states for the transition metals? I want data not just pictures! Thanks

[FONT="Comic Sans MS"]I am posting this to see if any readers/mentors, etc. can refer me to any type of reference for Rydberg states that also exhibit the quantum defect wherein we need to be concerned with the attractive force between the nucleus (or possibly, the ion core) and valence...

Hi, this is probably a straightforward question over something simple but it's confusing me. I don't get what the difference is between a mixed state, a superposition and a pure state. I'm looking through my notes about density operators and it's talking about a qubit system where |0> =...

Does it have to do with the fact that the molecules vibrate so close to each other, and transfer more energy to each other?

I'm pretty confused by the rules regarding the total energy, the kinetic energy, and potential of a QM system. Does the total energy have to be positive or greater than zero? And if so, why not? I don't really understand what it means to have a negative total energy of a system I guess. I...

Hi guys Say we are looking at a two-particle system consisting of two electrons (fermions). In my book it says that the basis states are given by \left| {\psi _{\alpha ,i} (r_m )} \right\rangle \left| {\psi _{\beta ,j} (r_n )} \right\rangle where rm and rn denote the two particles...

Homework Statement A hydrogen atom is excited from the state with n=1 to that with n=4. Calculate the energy (in eV) that must be absorbed by the atom. Calculate and display on an energy-level diagram the different photon energied (in eV) that may be emitted in order for the atom to reach...

Hi Guys/Gals If you end up with a row of zeros in the controllability matrix for a linear state space system, does that row correspond with the state that is uncontrollable eg. Assuming a linear state space system with 5 states, a row of zeros in the 4th row of the controllability matrix...

Homework Statement Show that, for all complexe numbers \alpha, a has a unique eigenvector |\alpha\rangle that is nothing else but the coherent state \psi(x)=\frac{e^{-\frac{i}{2\hbar}\langle X\rangle\langle P\rangle}}{(\pi\ell^2)^{1/4}}e^{-\frac{(X-\langle...

Which electron transitions in singly-ionized Helium (He+) yield photons in the blue (450-500 nm) portion of the electromagnetic spectrum? What are their wavelengths, and what transitions do they represent? Homework Equations hear is the equation I tried to use an equation creator but did not...

Homework Statement Consider a particle in a superposition of states given at time t=0 by Y(x,0)=C(y1(x)+y2(x)), where y1(x) and y2(x) are the stationary states with energies E1 and E2 respectively. if y1(x) and y2(x) are orthonormalized, what value of C is required to normalize Y(x,0)...