Re-Preparing vs Perturbing Quantum States: Understanding the Difference

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In summary, the difference between re-preparing and perturbing a quantum state is that re-preparing involves isolating the state from its environment and controlling interactions between its quantum building blocks to observe interference effects. Perturbing is a more general term and can have multiple meanings depending on the specific scenario and reference being used. To understand these concepts better, it is recommended to study quantum mechanics from a reputable textbook such as Ballentine.
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bluecap
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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?
 
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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?
 
  • #3
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?
 
  • #4
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.
 

FAQ: Re-Preparing vs Perturbing Quantum States: Understanding the Difference

What is the difference between re-preparing and perturbing quantum states?

Re-preparing a quantum state means creating the same initial state as before, while perturbing a quantum state means changing the initial state in some way.

Why is it important to understand the difference between re-preparing and perturbing quantum states?

Understanding the difference between these two processes is crucial in quantum computing and quantum information theory, as they have different effects on the resulting quantum state and can lead to different outcomes in experiments.

Can you give an example of re-preparing and perturbing quantum states?

Re-preparing a quantum state could involve resetting a qubit to its ground state, while perturbing a quantum state could involve applying a unitary operation to change the state of a qubit.

How does re-preparing and perturbing quantum states affect quantum entanglement?

Re-preparing the same quantum state does not affect entanglement, but perturbing the state can break or create entanglement between qubits.

Are there any practical applications for re-preparing and perturbing quantum states?

Yes, these processes are important in quantum error correction and quantum communication, where maintaining and controlling the state of qubits is crucial for accurate and reliable information processing.

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