The von Neumann Measurement Process: Explained and Explored

Click For Summary

Discussion Overview

The discussion centers on the von Neumann measurement process in quantum mechanics, specifically the interaction between a quantum system and a measuring device's pointer state. Participants seek clarification on the Hamiltonian formulation and the historical context of von Neumann's ideas.

Discussion Character

  • Exploratory
  • Technical explanation
  • Historical

Main Points Raised

  • One participant requests an explanation of the von Neumann measurement process, including the Hamiltonian formulation involving Dirac's delta function, an operator for measurement, and a momentum operator.
  • Another participant suggests checking von Neumann's original book for detailed information, implying it may not be readily available online.
  • A participant speculates about the language of von Neumann's book, noting its likely German origin due to his background.
  • A later reply confirms the availability of a new edition of von Neumann's book at a local library.
  • One participant provides biographical context about von Neumann, mentioning his Hungarian origins and American academic career.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the availability of resources or the specifics of the measurement process, as the discussion includes requests for information and suggestions rather than definitive answers.

Contextual Notes

Limitations include the lack of detailed explanations or examples of the measurement process, and the discussion does not resolve the complexities of the Hamiltonian formulation mentioned.

Who May Find This Useful

Readers interested in quantum mechanics, the historical development of measurement theory, or those seeking resources on von Neumann's work may find this discussion relevant.

trosten
Messages
47
Reaction score
0
Could somebody please explain or give me a link to an explanation of the idea about measerument that von neumann put forward. That is that a system interacts with a pointer state associated with the measurering device with the hamiltonian

H:=c * d(t) * A (X) * P

where d(t) is diracs delta, (X) is the tensor product, A is an operator representing what we measure and P is a momentum operator acting on the pointer state.

I have some understanding of this but I have failed to find a detailed explanation anywhere on the internet, just some notes that von neumann thought of it in 1932. I really would like to see some examples etc.
 
Physics news on Phys.org
Did u try to look in his book...?I'm sure u won't find the book on the internet,only at the library.

Daniel.
 
no I haven't but I assume that its written in german ? von neumann sounds kind of german!
 
Your right, my local library actually has a new edition of it, published in 96! thanks for the tip.
 
Johann (then John) von Neumann was a Hungarian-born American professor...

Daniel.
 

Similar threads

Undergrad von Neumann Measurement Scheme
  • · Replies 2 ·
Replies
2
Views
2K
Graduate What Are the Key Controversies in Quantum Measurement Theory?
  • · Replies 102 ·
4
Replies
102
Views
19K
Graduate Canonical Commutation Relations: Why?
  • · Replies 15 ·
Replies
15
Views
13K
Graduate Can anyone give me the details of creating a cat state in Circuit QED?
  • · Replies 16 ·
Replies
16
Views
5K
Graduate Asymptotic states in the Heisenberg and Schrödinger pictures
  • · Replies 8 ·
Replies
8
Views
3K
Graduate How does Bell's 1964 theorem address detector independence and local realism?
  • · Replies 18 ·
Replies
18
Views
3K
Graduate DMD is better without Ergodic Theory and Koopman Operators
  • · Replies 2 ·
Replies
2
Views
3K
Undergrad Can POVM measurements be explained by projective measurements?
  • · Replies 35 ·
2
Replies
35
Views
8K
Graduate Does Antony Valentini's "sub-quantum measurement" really work?
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Does Busch's Theorem Offer a Simplified Proof of Gleason's Theorem?
  • · Replies 54 ·
2
Replies
54
Views
12K