Relation between spin dephasing time T2* and spin relaxation time

In summary, the spin dephasing time of an ensemble of electrons, T2*, is related to the spin relaxation time of a single electron, T2, and is affected by the coherence parameter g_e, which is related to the spatial field homogeneity. The equation for this relationship can be derived from the precession of an electron in a magnetic field, as explained in most quantum mechanics textbooks or on Wikipedia's page on Larmor precession.
  • #1
rafaelg7
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Homework Statement: spin dephasing time
Homework Equations: spin relaxation time

Hello, i have seen the next equation that relates the spin dephasing time of an ensemble of électrons T2* with the spin relaxation of a single electron T2, and I would like to know how it was deduced/proposed:

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Thank you in advance
 
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  • #2
It would be helpful if you included more information from your text, particularly what g_e is. I'm guessing that it's some type of coherence parameter. The "dephasing time" cannot be longer than the electron's relaxation time, and is shortened by decoherence of the ensemble. I imagine that g_e is related to the spatial field homogeneity.
 
  • #3
marcusl said:
It would be helpful if you included more information from your text, particularly what g_e is.
It is the electron spin g-factor.

@rafaelg7: The equation comes from the precession of an electron in a magnetic field. You will find a derivation in most QM textbooks (as often, I recommend Cohen-Tannoudji for this). You can also look up
https://en.wikipedia.org/wiki/Larmor_precession
 
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Related to Relation between spin dephasing time T2* and spin relaxation time

1. What is the difference between spin dephasing time T2* and spin relaxation time?

Spin dephasing time T2* is the time it takes for the phase of a spin to become randomized due to interactions with its surroundings. Spin relaxation time, on the other hand, is the time it takes for the spin to return to its equilibrium state after being disturbed.

2. How are spin dephasing time T2* and spin relaxation time related?

Spin dephasing time T2* and spin relaxation time are related in that T2* is typically shorter than T1, the longitudinal relaxation time. This is because T2* includes both the effects of spin-spin interactions and spin-lattice interactions, while T1 only considers spin-lattice interactions.

3. What factors affect the spin dephasing time T2*?

The spin dephasing time T2* can be affected by various factors, such as magnetic field strength, temperature, and the presence of impurities or defects in the material. External disturbances, such as vibrations or electromagnetic noise, can also impact T2*.

4. How is the spin dephasing time T2* measured?

The spin dephasing time T2* can be measured using techniques such as spin echo or gradient echo spectroscopy. These methods involve applying a magnetic field pulse to flip the spins, and then measuring the decay of the resulting signal over time.

5. What is the significance of the spin dephasing time T2* in spin-based technologies?

The spin dephasing time T2* is an important parameter in spin-based technologies, as it determines the coherence time of the spin system. Longer T2* values allow for more precise manipulation and control of spin states, making them crucial for applications such as quantum computing and magnetic resonance imaging.

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