Questions tagged [two-level-system]
A quantum system that can exist in any quantum superposition of two independent (physically distinguishable) quantum states. Any two-state system can also be seen as a qubit.
125 questions
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Two-band model for semiconductors and hole picture
I was reading Czycholls Solid State Theory 1 for my Quantum Dot reasearch and came across the two band Hamiltonian with hole operators. After I changed the valence band electron operators to valence ...
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Fokker-Planck equation in the generalized $P$-representation of a two-level system
The Fokker-Planck equation (FPE) for a single transmon is well-known, and one can even obtain analytical expressions for the steady-state distribution (https://arxiv.org/abs/1606.08508) using the ...
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Simulating coherent 2-level system dynamics (preferably in Python)
I am reading through this paper on A short introduction to the Lindblad Master Equation and would like to reproduce the results in Box 3. To re-state the task in my own words: We have a Hamiltonian ...
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1answer
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Preparing a 2-level system along the $x$-axis of the Bloch sphere
I have a 2-level system (in my case 2 hyperfine levels) which starts in the ground state, $|{g}\rangle$. If I apply a $\pi/2$ pulse, which by definition has $\phi = 0$ as everything else is defined ...
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Two-photon fluorescence count rates for noble gases
How would one calculate the number of expected counts due to fluorescence after a two-photon excitation? Specifically, assume that a excited state $g$ is populated via two-photon process with a ...
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Maxwell-Boltzmann vs Fermi-Dirac vs Bose-Einstein statistics in a two-level (laser) system (with negative temperature)
The particles in a system of two-level particles are distinguishable and follow the Maxwell-Boltzmann statistics. Yet it then applies this model to laser. My questions are as follows. Since the atoms ...
- 1,100
4votes
1answer
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Two-level system and a classical oscillator - energy
I have solved two related problems and have some questions about the results. Forced classical oscillator with the following equation: $$\ddot{x}+\omega_{0}^{2}x=\varepsilon e^{-\gamma t}\sin\omega ...
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Two-level system in a thermal bath
I have a 2-level system, with the resonant frequency $\omega_0$ in a thermal bath, by which I mean that I have photons with mean frequency and standard deviation of frequency at a temperature $T$ ...
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1answer
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Which approach is accurate in deriving result of two level system, When probability of macrostate is unequal, probability or microstates approach?
I am concerned with accurate derivation of conclusions of two level system, When probability p and q are unequal, If there are two levels with energy 0 and E(actually it is epsilon, energy of a given ...
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Laser and excited state linewidths in Rabi oscillations
I want to simulate (numerically if analytically is not possible) the behavior of a 2 level system, when driven by a laser (basically transition probability vs laser frequency for fixed interaction ...
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Linewidth dependence on dipole moment, is it linear or quadratic?
I am trying to calculate the linewidth of a two-level system because of charge noise. I have modeled the charge noise in two ways. I mean, both kinds deal with the correlation of the electric field. ...
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Correlation function of a two-level quantum system coupled to a thermal bath
I am trying to quantify the temporal correlations of observables in an open quantum system, i.e. calculate a quantity of the type, \begin{equation} \langle n(t) n(t') \rangle - \langle n(t)\rangle \...
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3votes
1answer
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Adiabatic Approximation in the spin 1/2 System
I am studying the following Hamiltonian: $$H(t) = \begin{bmatrix} \frac{t\alpha}{2} & H_{12} \\ H_{12}^* & -\frac{t\alpha}{2} \\ \end{bmatrix}$$ I want to assume that $\...
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2answers
257views
Finite-time effects in Landau Zener
Consider a two level system with a Landau-Zener Hamiltonian of the form $$\hat{H}=\begin{pmatrix}v t&\beta\\\beta&-v t\end{pmatrix}.$$ The Landau-Zener formula provides a closed form for the ...
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Laser resonance phase shift
I understand in classical mechanics, for an driving force to be resonant with the oscillator and give force to it, there must be a $\pi/2$ phase shift (lag). My first question: is this the same for ...
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