Quantum Physics

- Mathematical description of the motion and interaction of subatomic particles. Quantum Mechanics & Field Theory
 Views: 8,613 Announcement: Two free ways to get Gold Membership! Jan17-12 Meta Thread / Thread Starter Last Post Replies Views Pinned: Quantum Physics Forum Rules Before posting anything, please review the Physics Forums Global Guidelines. If you are seeking help with a... Feb23-13 08:38 AM ZapperZ 1 29,541 How to find the Glebsch Gordan coefficients by matrix form. Let's suppose we have a two spin 1/2 particles, we get... Mar7-14 08:36 AM DrDu 3 153 I understand mathematically etc how light can doppler shift when looked at as a wave but can it be understood how... Mar6-14 09:54 PM The_Duck 2 187 we know that an electron rotates about its own axis.similarly does the electron too rotates about its own axis? and... Mar6-14 02:18 PM ZapperZ 2 174 The Wikipedia entry on uncertainty says, "Since the Robertson and Schrödinger relations are for general operators, the... Mar6-14 11:44 AM anorlunda 6 174 A laser's beam is split and then recombined, and the two path delays are adjusted so there is destructive interference... Mar6-14 10:42 AM Nugatory 8 243 I believe the title says it all. What is the first and second quantization? What is the difference? Thank you. Mar6-14 09:13 AM bhobba 3 168 In infinitely potential well problem ##V(x)## is zero inside the box and ##\infty## outside the box. Is it possible to... Mar6-14 02:40 AM vanhees71 35 722 Hi Guys, Newbie question from a layperson so please don't beat me up! :D I know that Heisenberg's Uncertainty... Mar5-14 07:12 PM FactChecker 13 306 Hi All, In the Feynman, 'sum over paths' approach to quantum field theory, we compute amplitudes, generating... Mar5-14 06:45 PM bhobba 3 329 Hey, I've been searching around for papers reporting on the creation of relatively large cat states, the largest I... Mar5-14 09:31 AM Gwinterz 2 212 Question and symbols: Consider a state|ε> that is in a quantum superposition of two particle-in-a-box energy... Mar5-14 08:44 AM Simon Bridge 12 384 Just a thought... Say that a stationary (relative to me) source of light emits a photon with the energy level (as... Mar4-14 07:43 PM samalkhaiat 7 293 If you ask me define Dirac delta function, i can easily define it and prove its properties using laplacian or complex... Mar4-14 05:50 PM bhobba 8 303 Hi, I was reading about interference patterns. I was wondering if the classical interpretation of... Mar4-14 11:32 AM UltrafastPED 1 185 I have read in popular literature that it is hypothesized that one could shoot particles through a pair of plates... Mar4-14 11:13 AM phinds 1 192 If in quantum physics some state is represented by ## \psi(x)=\sum_{k}C_k\psi_k(x)## ##C_m=\int \psi(x)\psi_m(x)dx##... Mar4-14 05:02 AM naima 3 240 Hi! I'm a little confused about simple spectroscopy. In typical absorption experiments, we scan the laser frequency w... Mar4-14 03:24 AM rrbbss 7 730 I went through an undergraduate physics program and I've internalized the results of the Stern–Gerlach experiment to... Mar3-14 10:58 PM WannabeNewton 14 577 I have a doubt on the second quantization formalism. Suppose that we have two spin-1/2 fermions which can have just... Mar3-14 03:50 PM Einj 2 185 Does Casimir plates prevent photon existence only perpendicular to them? I mean, Casimir attraction arises from the... Mar3-14 02:47 PM Naty1 6 317 Hi guys. Recentely I'm approaching Quantum Mechanics starting from the mathematical basics. In order to understand... Mar3-14 01:55 PM chimay 3 236 In any textbooks I have seen, vacuum states are defined as: a |0>= 0 What is the... Mar3-14 11:39 AM stevendaryl 13 430 Hi, imagine setup with source of entangled photons (A and B). Photon A travels to double slit so that either wave or... Mar3-14 11:16 AM DevilsAvocado 5 238 I was reading Mandle QFT book, and it says: "If we require the vacuum states to be invariant under Lorentz... Mar3-14 11:14 AM Einj 7 990 I can't figure this one out given that the coordinate operator is continuous, it's hard to imagine "matrix elements".... Mar3-14 10:53 AM Heisenberg 3 215 We know how to find S_{x} and S_{y} if we used S_{+} and S_{-}, and after finding S_{x} and S_{y}, we can prove that ... Mar3-14 07:46 AM ChrisVer 7 228 Why we don't have acceleration in quantum mechanics. For example why particle in infinite potential well can not... Mar3-14 06:47 AM ChrisVer 4 217 hi, please explain why do we need complex wavefunction in quantum mechanics? Mar2-14 09:02 PM ChrisVer 6 316 I have found that: For l = 1: \sum_{m=-l}^l |Y_l^m|^2 = \frac{3}{4\pi} For l = 2: \sum_{m=-l}^l |Y_l^m|^2... Mar2-14 08:59 PM Simon Bridge 4 222 if ψ(o)=(1 0)^{T} at time t=0. According to some Hamiltonian, it was found that the corresponding eigenstates are... Mar2-14 08:51 PM ChrisVer 1 161 Why we define that average value of some observable ##\hat{A}## in state ##\psi## is ##(\psi,\hat{A}\psi)## Why this... Mar2-14 04:46 PM LagrangeEuler 4 215 I'm reading the textbook "Silicon Nanoelectronics" and I've encountered an equation for the transmission probability,... Mar2-14 02:29 PM Achmed 6 250 In proving that for the norm to be preserved, U must be unitary. I ran across this: Re(λ<ø|ψ>)=Re(λ) if... Mar2-14 02:07 PM M. next 2 206 Hello, I just recently learned about angular momentum operator. So far, I liked expressing my operators in this... Mar2-14 12:12 PM oomphgalore20 5 401 Hi, if ket is 2+3i , than its bra is 2-3i , my question is 2+3i is in Hilbert space than 2-3i can be represented in... Mar2-14 06:43 AM stevendaryl 3 226 I’ve been trying to understand how having indistinguishable particles in a system changes the nature of the state... Mar1-14 11:41 PM strangerep 7 262 Hello, I am trying to recreate the double slit experiment using ordinary light, i.e. sunlight or light from a light... Mar1-14 05:12 AM craigi 4 221 I have questions about chapters 5 & 9 in Srednicki's book. 1. Below eq. (5.18), he says " is a... Mar1-14 02:49 AM JILIN 9 373 I have heard the argument that "decoherence" in quantum states causes the quantum collapse to occur, and that this... Feb28-14 01:10 PM atyy 82 1,655 In deriving the Heisenberg uncertainty relation for 2 general Hermitian operators A and B , the uncertainty operators... Feb27-14 05:13 PM dextercioby 3 274