State Definition and 1000 Threads

I need a book that explains the physics of pn-junction diodes. Really any reference that can help me characterize or model a diode slightly better than the ideal case.

Hi! According to the book "Renewable Energy on Power Systems" by Freris & Infield, the voltage rise due to injection of power in pcc can be estimated from the Thevenin equivalent representing the network "upstream" pcc (Figure 1). The Thevenin voltage can be taken as the nominal voltage in the...

Hi! 1. Homework Statement From the website http://www1.uprh.edu/rbaretti/MomentumspaceIntegration8feb2010.htm we can see the Fourier transform of the ground state hydrogenic wave function : Φ(p) = ∫ ∫ ∫ exp(-i p r) (Z3/π )1/2 exp(-Zr) sin(θ) dθ dφ r² dr (1.1) After intregation...

I am thinking of the usual "Alice and Bob" type scenario. If I choose to view the measuring instruments of Alice and Bob as "classical objects in spacetime", am I not then forced to say the following as well? 1) The joint-state of the measuring instruments is separable throughout the whole of...

Hello everyone. Iam just Learning about State space representation and controller design and have a fundamental question about the difference between classical Control theory and modern Control theory. I understood the state space is of advantage when dealing with MIMO systems or non-linear...

Hi All This is in relation to the folllowing paper: https://arxiv.org/pdf/1402.6562.pdf See section 3 on examples where standard probability theory is discussed. Is it valid? To me its rather obvious but I had had a retired professor of probability say probability theory doesn't have a state...

I often find that in books or lectures discussing the arrow of time and entropy and trying to explain how we have such complexity that the explanation is that when the universe was in it's early stage and was just a relatively small ball of apparently high entropy gas that it was in fact very...

I'm trying to understand chapter 19 of these lecture notes. But I have some difficulties with what the author explains: 1) In page 176, under equation 19.3 he says: This is weird. If we are considering a local QFT, then how can he say IR physics can cause non-locality? What is he talking...

I'm having some trouble finding consistent results for the derivation of the 1D phonon density of state. I'm applying periodic boundary conditions to a 1D monatomic chain. I can work through and find that D(K)=L/(2π). This is the same result as given by Myers (1990, p. 127). Myers uses only...

Homework Statement Hi everybody! I have a problem related to first-order perturbation theory, and I'm not sure I'm tackling the problem correctly. Here is the problem: Consider a hydrogen atom in an externally applied electric field ##\vec{F}##. Use first-order perturbation theory to find the...

I'm reading a thermo book and I'm on the chapter dealing with the first law of thermodynamics. The book is discussing functions of state and how the internal energy is a function of state because it has a well defined value at every equilibrium state of the system. It says that the work and...

Hi ! In my class we have an exercise that I technically understand but that I can't get conceptually. We have trois molecules (naphtalene, anthracene, tétracene). Considering each molecule as infinite quantum well of length 2L(naphtalene), 3L(anthracene) and 4L(tetracene), we would like to...

Hello! So I'm working to try to understand shor algorithm and I have some doubts. So, after the hadamard gates we apply the unitary gate that construct the function yk mod N. Next we do a measurement in the second register to get some function value. So, when I do this measurement on the...

1. Homework Statement Question (with the following definitions here): - Consider ##L_0|x>=0## to show that ##m^2=\frac{1}{\alpha'}## - Consider ##L_1|x>=0 ## to conclude that ## 1+A-2B=0## - where ##d## is the dimension of the space ##d=\eta^{uv}\eta_{uv}## For the L1 operator I am able...

Homework Statement A hydrogen atom transitions from ni= 5 state down to the ground state. a) What is the energy of photon emitted from the transition of the hydrogen atom? b) What is the ratio of the momentum of the emitted photon to the momentum of an electron which possesses the same kinetic...

Homework Statement Question: (With the following definitions here: - Consider ##L_0|x>=0## to show that ##m^2=\frac{1}{\alpha'}## - Consider ##L_1|x>=0 ## to conclude that ## 1+A-2B=0##- where ##d## is the dimension of the space ##d=\eta^{uv}\eta_{uv}## For the L1 operator I am able to get...

In a coherent state defined by |\alpha\rangle = \exp{\left(-\frac{|\alpha|^2}{2}\right)}\exp{\left(\alpha \hat{a}^\dagger\right)} |0\rangle there is a definite phase associated with the state by \alpha = |\alpha| \exp{\left(i\theta\right)} where the number operator and phase operator are...

What is the procedure for finding the unknown term(end value in this scenario) in a series? For example \sum_{r=1}^{n}{2r+3} My Attempt was to simply state the first four terms and then simply add the nth term as it is: 2(1)+3=5 2(2)+3=7 2(3)+3=9 2(4)+3=11 2(n)+3=2n+3...

My question is the following one: If i have the first excited state of helium, the possibilities for the two electrons are : 1s+,2s+ , 1s+2s-, 1s-,2s- and 1s-,2s+ , where + and - denotes spin up and down. If I use the slater's determinant to generate antisymmetric states, I get : $$|u1> =...

Homework Statement The question asks me to express the system shown in the image in state-space form, firstly by using the transfer function which was fine but the second part asks to express in state-space form by using the components A,B,C,D as the states x1,x2,x3,x4 Homework Equations U(s)...

Hey everybody,, I have question related to the expression of the maximally entangled state.. I know that that for W-state its given by ( For three qubits) : psi=(|100>+|010>+|001>)/sqrt(N) and for Disentangled state ( for three qubits) its given as : psi=|111> Where one and 0 represent the...

I might be accepted to the OSU physics PhD program and I have mainly an interest in cosmology / early universe stuff. How is OSU's program in cosmology? I hear their astronomy program is very good, but how is their cosmology especially?

Superconductivity does not occur in noble metals like gold and silver, nor in most ferromagnetic metals. Why is it so.

My question is conceptual but specific. I'm self-studying Townsend's text 'A Modern Approach to Quantum Mechanics.' In Sec. 2.2 pg 33 (in case you have the book handy), he introduces rotation operators, in the context of spin states for spin-1/2 particles. He states that the rotation operator...

Hi everyone. I'm designing a steady state feedback H2 control system. Actually, my major is tribology and I have no experience in designing control system. So it is really big problem for me. Anyway, this is my simple model of tribometer which applies normal load on the surface. (is it...

There seems to be a lot of conflicting research on nuclear winter theory, especially since the 1990s. Carl Sagan famously predicted that the Kuwaiti oil well fires from Operation Desert Storm would result in a small global winter, but the effects turned out to be more localized and less severe...

For the crystal lattices and structure Question picture is uploaded. Question.jpg My attempted answer is uploaded by a picture. My attempted ans. 1.jpg My attempted ans. 2.jpgThere is any mistake?

Homework Statement Given a wave function that is the super position of the two lowest energies of a particle in an infinite square well ##\Psi = \frac{\sqrt{2}}{\sqrt{3}}\psi _1 + \frac{1}{\sqrt{3}}\psi _2##, find ##\langle E \rangle##. Homework EquationsThe Attempt at a Solution I'm not sure...

Let's say we have a proposition (or state, if we prefer) ##P\equiv \psi \equiv AB^\perp + e^{j \theta} A^\perp B## where, e.g., ##A^{\perp}## indicates some ket that is orthogonal to ##A##. We also have an operator ##\hat{O}## . Without reference to a physical context, is there a test to say...

Homework Statement Homework Equations I = E / R_total The Attempt at a Solution I mostly just want to clarify that my thinking is correct. The solution for this problem shows that the current is split evenly between the two paths. Is that because we're assuming that the inductor has no...

Restricting to finite dimensional QP, suppose a system is in a state S1, an experiment is done, and state S2 is one of the eigenstates (assume all eigenvalues are distinct). The probability that the system transitions from S1 to S2 is p = Trace( S1*S2), using state operator notation. On the...

To me the state vector represents the following... 1) The number of elements in the state vector is the number of possible outcomes. Call that number n. 2) The value of each element in the state vector is the probability amplitude associated with that outcome. If that is true, then it seems to...

If a mode of light is in the single photon state in the reference frame of the emitter, what will the state look like in a reference frame where the wavelength is, say, 5% less or more? How about a state with, say, 5 photons? I saw some online discussions and some papers on arXiv (not...

Homework Statement Homework EquationsThe Attempt at a Solution These are what i solved except (e), I have no idea how to solve (e).

I think I got this right, I just want a second opinion to know if my concepts are correct 1. Homework Statement 20Na decays to an excited state of 20Ne through the emission of positrons of maximum kinetic energy 5.55 MeV. The excited state decays by ##\alpha## emission to the ground state of...

Does this mean that we will one day have an answer to the old age question on the ontology of the wave function: Towards optimal experimental tests on the reality of the quantum state http://iopscience.iop.org/article/10.1088/1367-2630/aa54ab

Hello. The entropy S is a state variable or state function as the integral of dS = dQ/T is a path-independent, provided that the path is reversible process path. However, such a path-independency of the integral breaks down when the path includes irreversible process. So, I guess we can only...

I am currently studying a Foundation Program, which includes chemistry. -I can easily understand the distinguishable characteristics between ground and excited state via writing the electron configuration. -But how can an tom changes from ground to excited state ? And can an atom changes from...

Was there ever a time in the distant past when there was absolutely nothing? I'm wondering about the big bang. If it started from a singularity then the singularity must have existed previous to the bang. Or, if there was absolutely nothing then that means the singularity did not exist. I am...

TL;DR: My professor asked me to graph the probability that a particle would be excited from the ground state to a stationary state with a certain energy E (y-axis) verse the energy of that new state (x-axis). I need help finding this probability as a function of E. Probability=|<ΨE|P|Ψg>|2 P is...

Homework Statement P(-5,-2) is a terminal point of angle theta in standard position. State the exact values of all the trigonometric rations for theta. Homework Equations x^2+y^2=r^2 csc=1/sin sec=1/cos cot=1/tan The Attempt at a Solution

What are the coordinates on the 3D Bloch ball of a qubit's mixed state of the form: ##\rho=p_{00}|0\rangle \langle 0|+p_{01}|0\rangle \langle 1|+p_{10}|1\rangle \langle 0|+p_{11}|1\rangle \langle 1|##

Homework Statement I'm trying to understand a derivation of the Fermi-Dirac and Bose-Einstein distributions. In my textbook Thermal Physics by D. V. Schroeder it says: "The idea is to first consider a "system" consisting of one single-particle state, rather than a particle itself. Thus the...

I'm major in chemistry my undergraduate.. and not good at Physics, Solid states... etc. I know pure graphene has two sub-lattice because it has two carbon atoms.. and something basic properties. then, why perfect graphene(no vacancy) is in nonmagnetic?

When an electron moves to lower energy state it emits a photon, now if a photon is absorbed by an electron does the electron move back to the higher energy state. (I don't think that 'energy state' is the right term) If so how hard is it to put the photon into the electron? I assume that it not...

I am in a quantum mechanics course based on the Griffiths text. When the books talks about the wave function on an electron in a specific state, it refers to the "complete state" of the electron as being the product of the spatial part and the spin part of the wave function. The need to...

Hello Forum, Could anyone offer some insight on this topic? In the case of a physical system composed of multiple particles, there is only one single wavefunction that depends on the three position variables of each particle and the parameter time t. For example, in the case of 2 particles, we...

Homework Statement The spin components of a beam of atoms prepared in the state ##|\psi_{in}\rangle## are measured and the following experimental probabilities are obtained, $$P_{+}=\frac{1}{2}, \quad P_{+x}=\frac{3}{4}, \quad P_{+y}=0.067$$ $$P_{-}=\frac{1}{2}, \quad P_{-x}=\frac{1}{4}, \quad...

My university lecturer is very new, his lectures and notes are hard to follow and understand. He was a replacement to the old solid state physics lecturer and has designed the module from scratch, so it is unpolished in its current form. Can you please suggest some alternative resources...

Homework Statement Let's consider conduction electrons (at T=0K) that are put in a magnetic field. The electrons can have spin that is parallel or antiparallel to the magnetic field. Below is the density of occupied states for such a system (horizontally) as a function of energy (vertically)...