# Quantum Physics

- Mathematical description of the motion and interaction of subatomic particles. Quantum Mechanics & Field Theory
 Meta Thread / Thread Starter Last Post Replies Views Views: 67,683 Announcement: Follow us on social media and spread the word about PF! Jan16-12 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 34,048 Hey everyone. I have a couple of question regarding wave function collapse. I can accept that one cannot make... May26-14 10:38 PM atyy 6 313 I'm in the first of 3 courses in quantum mechanics, and we just started chapter 4 of Griffiths. He goes into great... May26-14 10:15 PM jayqubee 5 350 Hi. I am reading a book entitled "Atom-Photon interactions" by Claude Cohen-Tannoudji, et al. There is a symbol... May26-14 08:50 PM UltrafastPED 1 181 "Locally, the spin density S is an intrinsic (i.e. origin-independent) quantity, which is associated with the local... May26-14 06:38 PM UltrafastPED 2 265 Am I right to think that particles cooled asymptotically to 0 K would have wave functions the size of galaxies or even... May26-14 04:59 PM QuasiParticle 11 446 Why is it the case that dual field tensors, e.g. \widetilde{F}^{\mu\nu}=\frac{1}{2}\epsilon^{\mu\nu\rho\sigma}F_{\rho... May26-14 11:53 AM guest1234 6 283 To which type of Fundamental forces below the Pauli's exclusion belong? Strong nuclear forces Coulomb forces Weak... May26-14 10:47 AM cgk 4 443 I have read a number of books on quantum mechanics and I am now at peace with the idea that the wave-function of an... May26-14 10:26 AM Mikeal 3 272 Here is an ultra short repeat of the Zeno Paradox, but please google it for a longer version with pictures etc: ... May26-14 08:37 AM DaleSpam 7 490 Hi! So let's say we measured the angular momentum squared of a particle, and got the result ##2 \hbar^2##, so ##l=1##.... May25-14 11:22 PM strangerep 6 288 Suppose we have a system with M nuclei and N electrons the electron density is defined as: ... May25-14 05:57 PM ChrisVer 10 391 Does the measurement problem ("wave function collapse") or something similar somehow manifest itself in QED and other... May25-14 09:47 AM DrDu 44 1,284 In the operation $$U(\Lambda)|{\bf p}\rangle=|{\Lambda\bf p}\rangle,$$ if we define the state covariantly, $$|{\bf... May24-14 02:51 PM Bill_K 2 187 I'm an electronics engineering student and I've only had a introductory one-semester course to quantum mechanics, so I... May24-14 01:17 PM UltrafastPED 5 449 hello i have to proof that Px (linear momentum operator ) is hermitian or not i have added my solution in... May24-14 10:31 AM Paul Black 5 316 In other words, must \mathcal{L}=\mathcal{L}^\dagger always be valid? May23-14 09:04 PM dextercioby 5 294 Greetings. I thought about how/ why light propagates slower trough matter than vacuum. Generally it is excepted that... May23-14 08:14 PM Vanadium 50 4 219 How is an ancillary bit used in a logic gate? I looked at http://en.wikipedia.org/wiki/Ancilla_(quantum_computing)... May23-14 09:59 AM BlackHole213 2 272 I have a couple of questions about entanglement and decoherence! 1. Sometimes you read that, strictly speaking,... May23-14 04:28 AM Demystifier 2 336 Forming the supersymmetric string using superfields and superspace, Polchinski claims that the function$$ G \sim... May22-14 07:25 AM Illuminatum 0 211 Hi. I've been learning quantum mechanics from different sources and I'm starting to notice that they have really... May22-14 07:04 AM carllacan 30 798 I read today about Ehrenfest's theorem on mechanical systems (with adiabatic hamiltonian evolution). Well in the... May22-14 05:01 AM PhilDSP 7 284 If a system is made up by two subsystems, for example, the atom and the photon. and let's assume the state of the... May22-14 12:09 AM micromass 3 340 Higher dimensional groups are parametrised by several parameters (e.g the three dimensional rotation group SO(3) is... May21-14 07:29 PM Matterwave 21 730 I'd like to ask a question to the members of the Quantum Physics board. Reading several articles regarding Quantum... May21-14 01:56 PM ZapperZ 1 293 The energy changes correspond to infrared, h_bar * w. Which particles are actually oscillating? The neutrons or the... May21-14 11:28 AM ChrisVer 6 400 In euclidean quantum field theory, the imaginary part of the free energy, defined as the logaritm of the partition... May21-14 09:14 AM LLSM 1 320 why are physisist having so much trouble quantising gravity and getting it to fit into QFT? May20-14 11:32 PM atyy 2 390 I've never really been...convinced...of the statement $$\bf{J}=\bf{L}+\bf{S}$$ I've always just gone along with... May20-14 10:24 PM Ravi Mohan 11 453 Let ψ be a wavefunction describes the quantum state of a particle at any (x,t), What does ψ* i.e, the complex... May20-14 07:26 PM UltrafastPED 6 240 Hi everyone, Lately I have been reading about the double slit experiment, I am wondering if it would be possible to... May20-14 06:10 PM mfb 3 324 I'm trying to get my head around this spin idea, the idea that particles behave like tiny dipole magnets when passing... May19-14 01:14 PM Jilang 25 934 The definition of tensor operator that I have is the following: 'A tensor operator is an operator that transforms... May19-14 10:51 AM CAF123 3 379 I am reading an intriguing article on rigged Hilbert space http://arxiv.org/abs/quant-ph/0502053 On page 8, the... May19-14 06:04 AM Ravi Mohan 2 169 Why, in a Gaussian wave function the position and momentum expectation value coincide to be zero? Does it have any... May19-14 03:52 AM BruceW 2 225 I have seen this question somewhere.. I diidnt get the answer. So plz help me. In how many ways three identical... May19-14 02:08 AM kashokjayaram 6 582 There are many cases, for simplicity, we choose the wavefunctions to be real. For example, in... May19-14 01:10 AM DrDu 2 278 Could someone provide me with simple answers to the following questions? I have tried to find the answers on the... May17-14 09:58 PM Simon Bridge 1 337 i mean, people are creating LHC to split the atoms, but why don't we just spin it? spin in in high speed and see if a... May17-14 02:30 PM mfb 1 291 I read a sentence that says if a spherical volume in placed in a quantized space then the maximum entropy of the... May17-14 01:09 PM Jilang 4 261