Quantum jitter vs thermal jitter

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Discussion Overview

The discussion revolves around the concepts of quantum jitter and thermal jitter, exploring their definitions, relationships, and implications in quantum mechanics. Participants examine whether quantum jitter can have thermal components and how these concepts are represented mathematically.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants reference Susskind's assertion that quantum jitter does not cause pain because it cannot borrow energy from the ground state, raising questions about the nature of quantum fluctuations.
  • There is a claim that quantum fluctuations exist for all states, but additional thermal fluctuations may occur in non-ground states.
  • A question is posed regarding whether quantum jitter can be partly thermal and how to define this property.
  • One participant suggests that a quantum jitter can indeed be partly thermal, proposing a mathematical representation involving the Hamiltonian.
  • Another participant questions the factorization of states into thermal and non-thermal parts, leading to differing opinions on the validity of this approach.
  • Inquiries are made about textbooks that describe states with thermal and non-thermal components, as well as the existence of a generalized Schrödinger equation.
  • One participant emphasizes the distinction between mixed-state and pure-state fluctuations, suggesting that thermal fluctuations are a specific case of mixed-state fluctuations and mentioning the Lindblad equation as an approximate approach for mixed states.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between quantum jitter and thermal fluctuations, with some agreeing that quantum jitter can have thermal components while others contest this notion. The discussion remains unresolved regarding the definitions and mathematical representations of these concepts.

Contextual Notes

There are limitations in the discussion regarding the definitions of thermal and non-thermal states, as well as the mathematical treatment of mixed and pure states. Unresolved mathematical steps and dependencies on specific interpretations are present.

naima
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In this book Susskind writes that if thermal jitter can burn our nerves, quantum jitter cannot. He explains why:
"Even though quantum jitters can be incredibly energetic, they cause no pain. Why? there is no way to borrow energy from the ground state. And quantum jitter is what is left over when the system is in its absolute minimum ground state."

I used to think that quantum fluctuations exist for all states. Could anyone elaborate this point?
Thanks
 
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naima said:
I used to think that quantum fluctuations exist for all states. Could anyone elaborate this point?
You are right, quantum fluctuations exist for all states. But for non-ground states there may be additional (e.g. thermal) fluctuations as well.
 
Can a quantum jitter be partly thermal? Is it a yes/no property and how to define when a quantum jitter is thermal?
 
naima said:
Can a quantum jitter be partly thermal? Is it a yes/no property and how to define when a quantum jitter is thermal?
Yes, a quantum jitter can be partly thermal. In this case the state of the system is a mixed thermal state proportional to ##e^{-\beta H}##,
where ##H## is the Hamiltonian.
 
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So with a complex ##\beta## we should factorize the state in a thermal and a non thermal part?
 
Is there a textbook in which a state is described with its two parts (thermal and non thermal)? Is there a generalized Schrödinger equation?
 
naima said:
So with a complex ##\beta## we should factorize the state in a thermal and a non thermal part?
No.
 
naima said:
Is there a textbook in which a state is described with its two parts (thermal and non thermal)? Is there a generalized Schrödinger equation?
I would not talk about thermal and non-thermal fluctuations. I would talk about mixed-state and pure-state fluctuations. Thermal fluctuations are nothing but a very special case of mixed-state fluctuations. Evolution of pure states is described by Schrödinger equation. A generalization to mixed states is not so simple, so let me just say that one approximate approach is based on the Lindblad equation.
 
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