Re-Preparing vs Perturbing Quantum States: Understanding the Difference

  • Context: High School 
  • Thread starter Thread starter bluecap
  • Start date Start date
Click For Summary

Discussion Overview

The discussion centers on the distinction between re-preparing and perturbing quantum states, exploring theoretical concepts related to quantum mechanics. Participants examine the implications of these terms and their usage in specific contexts.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant asserts that re-preparing a quantum state involves isolating it from its environment to observe interference effects.
  • Another participant questions the source of this information and requests a reference to support the claim about re-preparing.
  • A participant references a previous discussion, suggesting that re-preparing requires controlling interactions at a quantum level, but questions the meaning of perturbing a quantum state.
  • There is a discussion about the ambiguity of the term "perturb," with a participant stating that it has multiple meanings and requires a specific context to be properly addressed.
  • One participant criticizes the generality of the questions being asked, suggesting that they are not suitable for the current level of discussion and recommends studying quantum mechanics from a textbook.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the definitions and implications of re-preparing and perturbing quantum states. The discussion remains unresolved, with differing views on the clarity and specificity of the terms used.

Contextual Notes

The discussion highlights the need for precise definitions and contexts when discussing quantum states, as terms like "perturb" can vary in meaning. There is an indication that foundational knowledge in quantum mechanics is necessary for deeper understanding.

bluecap
Messages
395
Reaction score
13
Hi, what is the difference between re-preparing and perturbing a quantum state? I know re-preparing has to do with isolating it from environment and seeing interference effect. What about perturbing it?
 
Physics news on Phys.org
bluecap said:
I know re-preparing has to do with isolating it from environment and seeing interference effect.

Where do you know this from? What reference?
 
PeterDonis said:
Where do you know this from? What reference?

Reference? I saw you said in one of the old archives "To be able to "re-prepare" a piece of wood, you would have to first isolate it from its environment, and then control all the interactions between its quantum building blocks with sufficient accuracy to allow quantum interference effects to be observable. In principle that could be done, but in practice it is impossible.". So what does it mean to perturb a quantum state? What does perturb mean in standard usage? Isn't perturb same meaning as re-prepare?
 
bluecap said:
I saw you said in one of the old archives "To be able to "re-prepare" a piece of wood

Yes, and I put "re-prepare" in quotes because I was speaking heuristically. Plus, IIRC, the term wasn't mine; it was originally used by you in that thread, and I only used it because you did. So what did you mean by it?

bluecap said:
what does it mean to perturb a quantum state?

As it stands, this question can't be answered because it's too vague; "perturb" has multiple possible meanings. You would have to give a specific scenario and a specific reference (a textbook or peer-reviewed paper) where the term "perturb" is used.

The questions you are asking are much too general, and also are not really answerable at the "B" level, beyond the heuristic stuff I said in that prior thread. You really, really, really need to take the time to study QM from a good textbook (Ballentine, for example). As it is, I am closing this thread.
 

Similar threads

Graduate Exact symmetry, quantum states, and symmetric dynamics
  • · Replies 8 ·
Replies
8
Views
1K
Undergrad Understanding the dynamics of a perturbed quantum harmonic oscillator
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad How are good quantum numbers related to perturbation theory?
  • · Replies 18 ·
Replies
18
Views
4K
High School What does it mean for a glass bead to be in a quantum state?
  • · Replies 17 ·
Replies
17
Views
2K
High School Description of isolated macroscopic systems in quantum mechanics
  • · Replies 48 ·
2
Replies
48
Views
4K
Graduate Comparing Information Loss: Time Dilation vs. Decoherence
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Question about No-Cloning Theorem and State Tomography
  • · Replies 4 ·
Replies
4
Views
2K
Graduate TD perturbation - state initially in continuous part
  • · Replies 49 ·
2
Replies
49
Views
5K
Undergrad Is quantum interference an instantaneous consequence of superposition ?
  • · Replies 12 ·
Replies
12
Views
2K
Graduate Does there exist a proof for these conjectures?
  • · Replies 2 ·
Replies
2
Views
2K