Read about coherent state | 10 Discussions | Page 1

  1. P

    Quadrature distribution for an optical mode in the coherent state

    Hey there, the task i'm working on is written below. Find the quadrature distribution ρ(q), for an optical mode being in the coherent state |α>. Hint: use ∑Hn(x)*(t^n)/(n!) I really am struggling with this type of tasks :D I tried to follow a solved example that I found in my workbook, but...
  2. M

    A rather weird form of a coherent state

    As far as I know we can express the position and momentum operators in terms of ladder operators in the following way $${\begin{aligned}{ {x}}&={\sqrt {{\frac {\hbar }{2}}{\frac {1}{m\omega }}}}(a^{\dagger }+a)\\{{p}}&=i{\sqrt {{\frac {\hbar }{2}}m\omega }}(a^{\dagger }-a)~.\end{aligned}}.$$...
  3. CharlieCW

    Coherent states for Klein-Gordon field

    Homework Statement Show that the coherent state ##|c\rangle=exp(\int \frac{d^3p}{(2\pi)^3}c(\vec{p})a^{\dagger}_{\vec{p}})|0\rangle## is an eigenstate of the anhiquilation operator ##a_{\vec{p}}##. Express it in terms of the states of type ##|\vec{p}_1...\vec{p}_N\rangle## Homework Equations...
  4. N

    I What is the meaning of coherent states of mean photon number

    I am studying Quantum Cryptography and I am quite new in Quantum area. I have read an article and I found this confusing statement: My questions: 1. The three stage protocol implementing multiphoton. What is the meaning of coherent states of mean photon number? 2. How to describe the quantum...
  5. Dopplershift

    I Understanding Continuous Variable QKD

    So, I am doing my undergraduate research project in Quantum Cryptography, and I have some confusion in a few areas, especially in the topic of continuous variable quantum key distribution. From what I understand, Discrete Variable - Single photon. That is, for example, the BB84 protocol. Bob...
  6. V

    I How do I find this state |j,m=j> to calculate another state?

    I’m confused about how you find the vector |s;s⟩ to use in the general equation |θ,ϕ⟩=exp(−iϕS3) * exp(−iθS2) |s;s⟩ For spin Coherent states (From http://www.scholarpedia.org/article/Coherent_state_(Quantum_mechanics)#4._Spin_Coherent_States Eq 12) Or how you find the vector |j,m=j⟩ to use...
  7. V

    I Confusion about initial states and coherent states

    I've found online that the coherent state of the harmonic oscillator is |\alpha \rangle = c \sum_{n=0}^\infty \frac{\alpha^n}{\sqrt{n!}} | n\rangle where |n\rangle = \frac{(a^\dagger)^n}{\sqrt{n!}} |0\rangle and |0> is called the initial state. I've some code where I need to have this...
  8. B

    I The Lagrangian of a Coherent State

    How does one write a Lagrangian of a coherent state of vector fields (of differing energy levels) in terms of the the individual Lagrangians? I desperately need to know how to know to do this, for a theory of mine to make any progress. Please stick with me, if I didn't make sense just ask...
  9. P

    I Coupling Spin-0 and spin-1 fields

    My question is, how does one get a wave function for a 'combined' spin-1 and a spin-0 field? How is this possible? I have only been able to find combined states for equal spin identical particles. If you don't understand my question, I'll be glad to reword it.
  10. Q

    Harmonic oscillator coherent state wavefunction

    Hi, I am trying to find the wavefunction of a coherent state of the harmonic oscillator ( potential mw2x2/2 ) with eigenvalue of the lowering operator: b. I know you can do this is many ways, but I cannot figure out why this particular method does not work. It can be shown (and you can find...
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