State Definition and 1000 Threads

A particle of mass m that is under the effect of a one-dimensional potential V (x) is described by the wave function: \begin{array}{c} xe^{-bx}e^{-ict/\hbar }, x \geq 0\\ 0 , x \leq 0\end{array} where $$b\geq 0,c\in R$$ and the wave function is normalized. Is it a stationary state? What can...

Hi all - related to a question I asked some time ago: If one introduces a momentum cutoff, the result in the most basic case is Lorentz violation. That is, some form of preferred frame must be introduced. I'm wondering what this does to the vacuum state? That is, how does one keep the vacuum...

Hello, I was wondering if someone could help clarifying this question. The question asks to estimate the energy state difference between the vibrational ground state of S0,v=0 and the first excited vibrational ground state S0,v=1 of the spectra below. The given solution: S1,v=1 -> S0,v=1 at...

I was thinking about ballistic pendulums and the symmetry they exhibit. In the simplest case, you have one ball that begins at a certain height and collides with another ball at rest. You can calculate via conservation of momentum and energy the new velocities and max vertical displacements...

There is something I don't understand called CV Bell state measurement. In these two experiments they get two entangled beams "by overlapping phase-squeezed light with amplitude squeezed light with a phase difference of pi/2 at a 50-50 beamsplitter" See Figure 11...

Given the hamiltonian: \hat{H} = \hbar \omega_{0} \hat{a}^{+}\hat{a} + \chi (\hat{a}^{+}\hat{a})^2, where ##\hat{a}^{+}##, ##\hat{a}## are creation and annihilation operators. Find evolution of the state ##|\psi(t) \rangle##, knowing that initial state ##|\psi(0)\rangle = |\alpha\rangle##...

Five electrons are in a two-dimensional square potential energy well with sides of length L. The potential energy is infinite at the sides and zero inside. The single-particle energies are given by (h^2/8mL^2) (nx^2+ ny^2) where nx and ny are integers. The energy of the first excited state of...

I found the mean to be $$\langle n\rangle=\vert\alpha\vert^2 \tanh(\alpha^2)$ and $\langle n^2\rangle=\vert\alpha\vert^2 \left( \alpha^2\sech(\alpha^2)^2 + \tanh(\alpha^2) \right)$$. Do you know if there is any reference where I can check if this is correct?

In Sheldon Glashow's critical review of "What is Real? The Unfinished Quest for the Meaning of Quantum Physics" by Adam Becker, there is one paragraph I don't understand. In Glashow's thought experiment of a single radioactive atom in a box: My thought experiment is like Schrödinger’s, but...

A recent thread by @coolcantalope was accidentally deleted by a Mentor (I won't say which one...), so to restore it we had to use the cached version from Yahoo.com. Below are the posts and replies from that thread. The cached 2-page thread can be found by searching on the thread title, and is...

Hi everyone. Using the Green function, I want to obtain the density of states of a one-dimensional (linear) lattice. Depending on the problem conditions, we will have an iterative loop with 4,000 data for the energy component and a iteration loop with 2,000 data for the wave number component. In...

PROGRAM DensityOfState IMPLICIT NONE INTEGER :: omega , t0 , a0 ,kx omega=1 ; t0 =1 ; a0=1 REAL :: kx , eta , w , ek eta=0.0015 REAL,PARAMETER :: pi=3.14 COMPLEX , PARAMETER ::i=(0,1) COMPLEX :: Energy COMPLEX :: Density COMPLEX :: GreenFunc...

From an excel file I can get the probability of each energy state Εi and I saw at Wikipedia that the probability of each energy is proportional with e^−Εi/KT, from this I find the energy of every micro state. Also from the formula which I found on a paper I can get a curve like the curve...

In Elements of Gasdynamics the author describes what he calls The Canonical Equation of State where (∂E∂S)v=T and (∂E∂V)s=−P He does a simple one for a perfect gas and uses the enthalpy(T,V) for the Canonical Equation of state. Now he asks to find the Canonical Equation of State for E(V,S)...

What is the best books about the history of solid state physics? I only found this: Out of the Crystal Maze: Chapters from the History of Solid State Physics by Lillian Hoddeson Are there any other books? Thanks for your suggestions

Hi, I have a question about a homework problem: I am not sure why I do not seem to get the same answers when using different methods. Question: Given transfer functions G(s) = \frac{s - 1}{s + 4} and C(s) = \frac{1}{s - 1} , find the state space models for those systems. Then find the...

The answer for triangular net is -3NJ, so D=3, although I think that it has two dimensions in spite of every atom having three near neighbours.

The wave function or Schroedinger equation is timeless, correct? You can reverse the equations and forward it. Our arrow of time comes due to decoherence in macroscopic object. How about energy bands in solid state. Do you consider it as timeless wave function, or is it decohered?

Hello all, Im trying to come up with a simple method (and design) for detecting (mostly and foremost next to transmitting) a (continued) HIGH or LOW state through a specific frequency, most likely in the 420-450Mhz range. Without the possibility of interference. Preferably analog, at least on...

I'm struggling with my Final Degree Project. I would like to perform a quantum simulation and perform quantum tomography for a single-qubit using a resrticted Boltzmann machine. In order to do so I'm trying to follow the recipe in the paper "Neural Network quantum state tomography, Giacomo...

Hello fellow physicists, I have a homework assignment which is to make a scientific essay (10-15 pages long) on neutron scattering in solid state physics. Our teacher is kind of the worse and he hasn't specified what he wants it on. He just said what I'm telling you: "An essay on neutron...

In the simple harmonic oscillator, I was told to use the raising and lowering operator to generate the excited states from the ground state. However, I am just thinking that how do we confirm that the raising operator doesn't miss some states in between. For example, I can define a raising...

Homework Statement:: I'm working on a personal project to convert objects from a simulation using state vectors for position and velocity to Keplerian orbital elements (semimajor axis, eccentricity, argument of periapsis, etc.). However, the equations I am using do not calculate the...

How did you find PF?: Google I am studying the mechanical/electrical nature that govern certain nano-fabricated crystalline structures. Can someone with experience please recommend a 3d Solid State Simulation software that will allow me perform the following: Allows individual 3D placement...

In P&S, it is shown that $$e^{-iHT}\ket{0}=e^{-iH_{0}T}\ket{\Omega}\bra{\Omega}\ket{0}+\sum_{n\neq 0}e^{-iE_nT}\ket{n}\bra{n}\ket{0}$$. It is then claimed that by letting $$T\to (\infty(1-i\epsilon)) $$ that the other terms die off much quicker than $$e^{-iE_0T}$$, but my question is why is this...

Hi, does general relativity have state variables, analogous to current (I), charge (Q), voltage (V), and flux (Φ) in electromagnetism? Thanks.

This is an iff statement, so we proceed as follows ##\Rightarrow## We assume that ##|\phi \rangle## is uncorrelated. Thus the state operator must be of the form ##\hat \rho = \rho^{(1)} \otimes \rho^{(2)}## (equation ##8.16## in Ballentine's book). The spectral decomposition of the state...

I've been think about it for hours but I'm really out of clue here... The only things I could think of are obvious or useless... Any help would be greatly appreciated.

Starting with finding the probability of getting one of the states will make finding the other trivial, as the sum of their probabilities would be 1. Some confusion came because I never represented the states ##|\pm \textbf{z}\rangle## as a superposition of other states, but I guess you would...

For which field is there more demand in the industry? And is knowledge of quantum electronics/optics useless without having a phd, as I see most job offers ask for a doctorate degree. Are the skills and knowledge from quantum electronics transferable to engineering positions or is what you...

By definition , ##\ket{+x} = \alpha \ket{+z} + \beta \ket{-z}.## Therefore we proceed , \begin{align*} \langle S_{x} \rangle &= \lvert \alpha \rvert^{2} \left(\frac{\hbar}{2}\right) + \lvert \beta\rvert^{2} \left(-\frac{\hbar}{2}\right) = (\alpha^{2} - \beta^{2})\left(\frac{\hbar}{2}\right).\\...

Hello everyone! I'm trying to implement a quantum circuit that yields a superposition state $$\frac{1}{\sqrt{2}} (|01 \rangle + |10 \rangle)$$ I'm using parameterized gates to achieve this. I have been able to create the state $$\frac{1}{\sqrt{2}}(|01\rangle + e^{i\phi} |10 \rangle)$$ Is there...

If my partition function is for a continuous distribution of energy, can I simply say that the probability of my ensemble being in a state with energy ##cU## is ##e^{-\beta cU} /Z##? I believe that isn't right as my energy distribution is continuous, and I need to be integrating over small...

Summary:: I have two substances H2O and CH3OH given at a temperature T and pressure P. I also have critical temperatures and pressures. How can I find the physical states of these substances. My teacher recommended me to use the Antoine equation and find the saturation pressure, but I can't...

Here is the figure: The answer is $$Q_A<Q_B$$ which I can show by calculation using the above equations. What's confusing to me is I thought that the change in internal energy was a state function. Which would mean since the initial and final points are the same, $$\Delta E_A=\Delta E_B$$ or by...

Recent Science headlines are abuzz about a new theory. Physicists claim information is the fifth state of matter. By 2245, half of Earth’s mass could be converted to digital bits https://www.zmescience.com/science/news-science/information-fifth-state-matter-0252/ Digital Information Threatens...

A very interesting paper was recently released that's a follow up to the paper that talked about Time Reversal to a known state. If you remember a lot of papers talked about how they reversed time. Here's more from the new article. Basically, Schrodinger's equation is reversable and there's no...

I've got a question here which I'm really unsure what the wording is asking me to do, I've calculated (5), so worked out the steady states. However question 6 has really thrown me off with it's wording, any help would be appreciated.

I've got 2 questions here. I was able to work out question 5 and calculate the steady states. However for question 6 I've got no idea with the wording of the equation and where you would start, so any sort of help would be really helpful, cheers

Got a steady state question and was wondering if anyone would be able to check if I'm on the right track? Find the steady states of these two equations: My working out as far: \[ 0=u*(1-u*)(a+u*)-u*v* \] \[ 0=v*(bu*-c) \] I looked at the 2nd equation first giving: \[ v*=0, u*=c/b \]...

Hi all, thanks in advance for your help! For context, I'm generally new to condensed matter and many-body QM and am working through Altland and Simons' Condensed Matter Field Theory. I'm thinking in general about magnetic ordering. I've seen a Heisenberg-like spin Hamiltonian derived by...

Practically it is said that, given two spin states |u⟩ (up) and |d⟩ (down) - which are the spin measured along the +z and -z semiaxes - such that they are orthogonal ( ⟨u|d⟩ = ⟨d|u⟩ = 0), it is possible to write any other spin states using a linear combination of these two (because they are a...

In a recent paper submitted by the LHCb collaboration at arXiv, they have reported a tetraquark state composed of charm quarks and antiquarks. The statistical significance of the data is more than 5σ. The abstract: An article on this paper...

My teacher was teaching me that how work done in isothermal reversible expansion is greater than irreversible expansion and also work done in isothermal irreversible compression is greater than that for reversible compression. He then said if someone tries to go from 1st state to the 2nd step (...

I am a bit confused about how kets in dirac notation are working. I read on wikipedia, that kets are linear, so |a*Φ>=a*|Φ>. Also I read (https://ocw.mit.edu/courses/physics/8-05-quantum-physics-ii-fall-2013/lecture-notes/MIT8_05F13_Chap_04.pdf) that this is not true for the position state ket (...

I've been thinking about this but now especially with regards to Covid-19 there are a lot of theories out there starting from absolute fringe and lunacy to somewhat scientific and even ones with sources to academia. For starters not to get too long my question is, What is our current known...

The energy spectrum of a particle in 1D box is known to be ##E_n = \frac{h^2 n^2}{8mL^2}##, with ##L## the width of the potential well. In 3D, the ground state energy of both cubic and spherical boxes is also proportional to the reciprocal square of the side length or diameter. Does this...

Is my answer correct?