Absorption and emission spectrum in quantum optics

In summary, resonance fluorescence is a phenomenon where light is emitted from a quantum dot, atom, or defect center when an electric field is applied. The emission spectrum or resonance fluorescence for a quantum dot, atom, or defect center are discussed in many quantum optics textbook, for example see "Quantum Optics" by Marlan O. Scully and M. Suhail Zubairy Chapter 10 , "Quantum Optics" by D. F. Walls and Gerard J. Milburn Chapter 10 and "Quantum Optics" by Raymond Chiao and John Garrison Chapter 14.
  • #1
Cedric Chia
22
2
TL;DR Summary
Absorption spectrum for a quantum dot
The emission spectrum or resonance fluorescence for a quantum dot, atom or defect center are discussed in many quantum optics textbook, for example see "Quantum Optics" by Marlan O. Scully and M. Suhail Zubairy Chapter 10 , "Quantum Optics" by D. F. Walls and Gerard J. Milburn Chapter 10 and "Quantum Optics" by Raymond Chiao and John Garrison Chapter 14.

In these textbooks, the formula for resonance fluorescence is given by:
$$
\alpha(\omega)=Re\int_0^{\infty}dt\left<E^{(-)}(t)E^{(+)}(t+\tau)\right>e^{i\omega\tau}
$$
where one usually relates the electric field operator with the atomic raising/lowering operator:
$$
\left<E^{(+)}(t)\right>\propto\left<\sigma\right>
$$

But what about the formula for absorption spectrum? Where can I find discussion on the absorption spectrum? And what if I have a system coupled to local vibrational modes (a polaron), how would that change the formula of emission and absorption spectrum?
 
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I know very little about quantum dots, but I do remember a review paper on spectral line shapes: van Vleck J H and Huber D L 1977, Rev. Mod. Phys. 49, 939-959. Both, absorption coefficients and emissivities can be expressed in terms of Fourier transforms of the dipole moment auto-correlation function, or more generally, of the current density fluctuations.
 
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  • #3
WernerQH said:
spectral line shapes: van Vleck J H and Huber D L 1977, Rev. Mod. Phys. 49, 939-959. Both, absorption coefficients and emissivities can be expressed in terms of Fourier transforms of the dipole moment auto-correlation function, or more generally, of the current density fluctuations.
Is this not found in spectroscopy texts/monographs (or at least rather quantum mechanical ones as opposed to semiclassical)?
 
  • #4
That's a very general basic principle. In linear-response theory the response function is given in terms of the (retarded) autocorrelation function of the source. It's also known as the Green-Kubo formula.
 
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FAQ: Absorption and emission spectrum in quantum optics

What is an absorption spectrum?

An absorption spectrum is a graph or plot that shows the wavelengths of light that are absorbed by a particular substance. It is created by shining a continuous spectrum of light through the substance and measuring the intensity of light that passes through. The dark lines on the spectrum indicate the wavelengths that have been absorbed by the substance.

How is an emission spectrum different from an absorption spectrum?

An emission spectrum is also a graph or plot that shows the wavelengths of light, but in this case, it represents the wavelengths of light that are emitted by a substance. It is created by exciting the substance and measuring the wavelengths of light that are emitted as the substance returns to its ground state. The bright lines on the spectrum indicate the wavelengths of light that are emitted.

What is the relationship between absorption and emission spectra?

The absorption and emission spectra of a substance are directly related. The wavelengths of light that are absorbed by a substance are the same wavelengths that are emitted when the substance returns to its ground state. This is known as the principle of spectral reciprocity and is a fundamental concept in quantum optics.

How is quantum optics related to absorption and emission spectra?

Quantum optics is the branch of physics that studies the interaction between light and matter at the quantum level. It is closely related to absorption and emission spectra because these phenomena can only be fully understood and described using quantum mechanics. Quantum optics helps us understand the behavior of atoms and molecules in the presence of light, which is crucial for understanding absorption and emission spectra.

Can absorption and emission spectra be used to identify substances?

Yes, absorption and emission spectra are often used in analytical chemistry to identify substances. Each substance has a unique pattern of absorption and emission lines, which can act as a fingerprint for that substance. By comparing the spectra of an unknown substance to a database of known spectra, scientists can determine the identity of the substance.

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