State Definition and 1000 Threads

This concept is rather interesting : "Excitation of two atoms by a propagating single photon pulse" -- http://arxiv.org/abs/1411.3445 . They say that, in principle, one can tailor an optical pulse so that it will excite two atoms from the ground state (i.e., the |gg> state) so it ends up in any...

Homework Statement Assume a particle is in the ground state of an infinite square well of length L. If the walls of the well increase symmetrically such that the length of the well is now 2L WITHOUT disturbing the state of the system, what is the probability that a measurement would yield the...

I'm relatively new to QFT and was wondering how the QED vacuum has a dormant zero average-field condition if there is a zero-point energy of the field as well? How is there a zero average and a zero point energy?

There's a somehow related set of issues I find myself pondering time and again: In 1995, Ted Jacobson derived Einstein's equations from thermodynamics across a horizon. Roughly, he showed that if the horizon's entropy is given by the Bekenstein-Hawking formula, then the second law of...

Can someone give me a simple explanation of how to measure the Rabi probability oscillations in a two state atom?

Hey everyone! It's my first semester with quantum mechanics and I'm uncertain if my solution of this problem is correct, would be nice if someone could check and let me know :smile: 1. Homework Statement I have to calculate the representation of the state: |\alpha \rangle \equiv exp[-i...

At first, we need some state parameters(like P/T/V) to fully describe a system. And the order parameter is also a parameter which could describe the property of the system. However, in the Laudau theory, why it said that order parameter is an external parameter(not a independent variable)? Is...

A wavefunction of a single particle (ignoring spin etc) is a three dimensional object mapping to 3-D physical space. The wavefunction of two unentangled particles is separable as a product of two independent 3-D wavefunctions. If the particles are entangled, the states cannot be separated, the...

I can understand that the state of a particle is not known or even determined until it is viewed. What about a deck of cards that have been thoroughly shuffled and not looked at. Can the top card take on the value of any card before they are looked at or are they set at the time they are...

I am having trouble understanding this. The question was how to limit breakaway oversteer I know that putting the CG to the rear will increase the rear traction and induce understeer as there is less grip on the front tyres. However, I have also found that to reduce oversteer you want to...

Greetings , Is the zero potential level ( not the ground state) considered as an excited state ? and why the ground state isn't an excited state ?

1. The problTfem statement, all variables and given/known data Determine the result when 100g of steam at 100C is passed into a mixture of 200g of Water and 20g of ice at exactly 0C in a calorimeter which behaves thermally as if it were equvalent to 30g of water. Homework Equations FInding the...

I want to see if we can map the space that is computable programs. You wouldn't consider complex problems, once you mapped the simplest problems into a space of points you can get a distribution. You may see that these clump. Seeing as several of the variables are proportional to the history of...

Homework Statement Ok, don't get angry with me. The original problem is from Solid State Physics but my problem is very well in "Introductory physics". Here is the problem: The chain consists of molecules, which has three atoms, each with mass ##M##. Spring constant between the atoms inside...

What are the number of states available to the electrons, and what is the difference between the ease of getting electrons to change states considered against the ease with which they change states by themselves? Can you give an example where they change states by themselves?

In solid state physics, I learned that the velocity of a bloch electron is ##\frac{\partial E(k)}{\partial k}##, where ##E(k)## is the energy dispersion. This formula is derived on the basis of the assumption that electrons is a wave packet of bloch state in solids. However, I have a question...

The GHZ state is: |\psi> = \frac{|000> + |111>}{\sqrt2} To calculate density matrix we go from: GHZ = \frac{1}{2}(|000> + |111>)(<000| + <111|) GHZ = \frac{1}{2}( |000><000| + |111><111| + |111><000| + |000><111|) To: GHZ = 1/2[ \left( \begin{array}{cc} 1 & 0 & 0 & 0 & 0 &...

Homework Statement Homework Equations $$ \psi_{100} = \frac {1}{\sqrt{\pi a^{3}}} e^{-r/a} $$ The Attempt at a Solution a) $$\langle r \rangle = \frac {1}{\pi a^{3}} \int_0^{2 \pi} d \phi \int_{0}^\pi d \theta \int_0^{\infty} r^{3} e^{-2r/a} dr$$ This comes out to be ##\frac {3}{2}a##...

Does anybody know where I could find worksheet to practice naming the state of matter in chemical reactions (with answers in the worksheet to check) as I have problems with that. Especially deciding when it is aqueous. I know (well at least i am right) that when you have acid as reactants it has...

Hello PF! I have some questions regarding the accumulation term for the energy balance on a variable volume system. Suppose we have a tank storing a liquid substance. The tank has a moving boundary at the top, which can expand unlimitedly. The system has a mass input \dot{m}_1 and mass output...

Homework Statement Consider the equation: 3logx5+2logx2-log1/x2=3 a)State which values of x for which the equation is defined. b)Solve the equation for x. Homework EquationsThe Attempt at a Solution 3logx5+2logx2-log1/x2=3 =logx53+logx22-log1/x2=3 =logx125+logx4-log1/x2=3 =logx500-log1/x2=3...

Homework Statement Rewrite the state |ψ⟩ = √(1/2)(|0> + |1>) in the new basis. |3⟩ = √(1/3)|0⟩ + √(2/3)|1⟩ |4⟩ = √(2/3)|0⟩ − √(1/3)|1⟩ You may assume that |0⟩ and |1⟩ are orthonormal. Homework Equations The Attempt at a Solution [/B] I have a similar example in my notes however there...

Homework Statement I am working through a time independent perturbation problem and I am calculating the first order correction to the energy, and I am stuck operating the perturbation : v = i b (Exp[i g x]-Exp[-i g x]) on the ground state |0>. Homework Equations <0| v |0> = 1st order...

f(z) = z2 + c

first paperhttp://arxiv.org/abs/hep-th/0209079 Quantum gravity with a positive cosmological constant Lee Smolin 59 pages "A quantum theory of gravity is described in the case of a positive cosmological constant in 3+1 dimensions. Both old and new results are described, which support the case...

In nuclear physics we have talked about the liquid drop model and the fermi gas model. My question is can a Fermi liquid and a Fermi gas be directly described using these models? Are they the same thing? i.e. If I wanted to decribe the difference between a fermi gas and a fermi liquid could I...

Not to repeat what is already said, my thoughts are more or less the 4 points mentioned here: http://physics.stackexchange.com/questions/132007/quantum-entanglement-an-illusion-based-on-a-wrong-assumption The upvoted answer to what gpgemini's said is that this assumption is essentially what...

Homework Statement I am given this state, which is the result of a lamba particle decaying into a proton and neutral pion. Initial j = 3/2. The final state can theoretically be written as: I have already determined that: alpha_p = Sqrt[2/3] beta_p = Sqrt[1/3] alpha_d = -/+ Sqrt[2/5]...

Im trying to wrap my head around this. If a photon of the right energy hits an atom's electron (hydrogen e.g) it jumps to the next orbital shell, then goes back down to conserve energy releasing a photon in the process. is this how we see the atoms in everyday matter? by the switching of the...

Hello, In which way nano and solid state physics improve technology? where we use statistical physics more in nano physics or particle physics? where we use quantum mechanics more in nano physics or particle physics? which major is more enjoyable nano or particle physics? which major is more...

Homework Statement A satellite is orbiting Earth with a period time of T=110 min. At the ascending node, the state vector of the satellite is rAN =[4500 7100 ?]T km At the northernmost latitude, the state vector of the satellite is rn=[1700 ? 7000]T km. The question marks imply that the...

Homework Statement Imagine a hypothetical process in which the methane molecule, CH4, is "expanded," by simultaneously extending all four C−H bonds to infinity. We then have the process: CH4 (g) → C(g) + 4H(g) Compare the reaction for the "expansion" of methane with the reverse of the reaction...

Homework Statement While studying alkaline Earth metals of the s block elements I found this equation : Be (OH)2+2HCl +2H2O →[Be (OH)4]Cl2 It is clear that in the complex, the oxidation state of Berrylium is +6. But how is even that possible? Homework Equations None The Attempt at a...

All that I've read about black holes describe something so massive it's gravity overcomes all other forces and it causes a region of spacetime to develop that no particle or electromagnetic radiation can escape from. That explanation since it depends on mass makes no sense in regard to...

In section IIIA (p11) Max Tegmark tries to prove that the integrated information Φ of a bell state is zero. The definition of Φ that Tegmark uses is given by the mutual information I minimized over all possible factorizations. The bell state has I=2 when written in the usual basis. Tegmark...

Homework Statement A cylindrical tank, with a diameter Db, open to the atmosphere, is drained through an orifice in the bottom of the tank with a diameter Do. The speed of the fluid flowing through the orifice is given by v = \sqrt{2gh}, where h is the height of the liquid measured from the...

Homework Statement [/B] ZnS crystalizes in the B3 type structure with the space group is F¯43m. This structure is shown below and can be regarded as the bi-atomic form of the diamond lattice (F d¯3m). Upon applying a force along the [1,1,1] direction, the crystal might experience a change in...

I have a few questions about entropy and path Scenario I have a closed system of Ideal Gas- Volume is Fixed , Mol Vol is fixed. At room temperature the system is in thermal equilibrium with its surroundings I then cool this system removing Q . To this system I then re-add Q until it is again in...

To my understanding, QED is about electromagnetic interaction, and in a solid system, the interaction is only electromagnetic So why there are stills lots of research in solid state physics ? Is there something not explained by QED ?

Hello everybody, For my thermodynamics test I have to tell whether or not a quantity is a state function, which is obviously not all too difficult when regarding entropy, enthalpy etc. on their own. However there are a lot of questions where it is about "H-S" or "G-H". Are these not always...

Homework Statement a) If a spin-1/2 particle is in the up spin state along z, what is the probability that if its spin along the y-direction is measured it will be found to be pointing in the “up” direction along y? (b) Calculate the expectation values of the components of S, i.e. {Sx, Sy...

Firstly, I apologise for any lack of understanding, incorrect assumptions or misinterpretations of the very little I know about physics, quantum mechanics & quantum computing. I am not an academic, scientist or mathematician, but a software engineer with an interest in quantum computing and...

In 1-D if I have an infinite potential at x<0 so the wavefunction is zero for x<0 but for x>0 the potential is zero so the wavefunction oscillates to infinity is that a bound state ? I presume this isn't bound as it can't be normalized but most definitions state that bound means the wavefunction...

I'm really confused about Energy and Entropy's equations of state, and how their differentials work. So I find everywhere that H = U + PV. And so dH = d(U +PV) = dU + PdV + VdP Ok, that makes sense. But then I look at energy and try to get the equation of state dU = δqrev + δwrev. That also...

A neutral atom of radium isotope may be represented by: 228 Ra (88 proton number, 228 nucleon number). 88...

Homework Statement For the circuit in (Figure 1) , suppose va=10cos16,000tV vb=20cos4000tV. Suppose that R = 700Ω . Write the steady-state expression for io(t) as io=I′ocos(ω′t+ϕ′)+I′′ocos(ω′′t+ϕ′′), where −180∘<ϕ′≤180∘, −180∘<ϕ′′≤180∘, and ω′>ω′′. Find the numerical value of I′o. Find the...

Homework Statement VHDL code: http://i.imgur.com/UZrK1ky.pngHomework Equations B2 = B7 * A1 B3 = (B9 * B2) + (B1(1) * /B1(0) * /A1 B6 = B9 + /A1 B8 = B2 + (B9 * /A1) + (/B5 * (A1 + B7)) If Clock = 1 and rising edge on A2 then we reset B4, B5, B7 to 0. Else B4 = B3 = (B9 * B2) + (B1(1) * /B1(0)...

Homework Statement For a hydrogen-like “atom” (e.g., He+ ion), with nuclear charge Ze, it is claimed that the the ground-state wavefunction is spherically symmetric and is given by ψ(r)=Aexp(−αr) , where A and α are constant. (a) Determine the normalization constant A in terms of α. (b)...

Homework Statement Determine the state of stress at point A on the cross section at section a−a of the cantilever beam. Take P = 350kN . Homework Equations Um . . . σ = P/A ? The Attempt at a Solution Yeah I'm not quite sure. I thought it was P/A, using 350000N as "P" and 300000mm^2 as A, but...

Hi, thank you for your help in advance. I have a circuit configured as shown in this image. I got this arrangement from an earlier thread. An arduino controls a DC solid state relay, and it works fine when my load is a simple LED. The arduino is controlling through a digital output header and...