Can Multiple Competitive Operators Transform a Quantum State Simultaneously?

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Discussion Overview

The discussion revolves around the possibility of multiple competitive operators acting on a quantum state simultaneously, exploring the implications of such interactions in quantum mechanics. Participants reference various experiments and theoretical concepts related to the measurement of quantum states, particularly focusing on position, momentum, and Hamiltonian operators.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about experiments where a quantum state experiences changes due to three competitive operators, specifically asking for examples and the largest systems studied.
  • Another participant cites the Stern Gerlach experiment as a familiar example of switching measurement operators, noting that rotating the apparatus changes the measured spin component.
  • It is suggested that most experiments involve changing operators based on what is being measured, such as transitioning from measuring position to measuring energy, rather than explicitly switching operators in a theoretical sense.
  • The concept of quantum numbers is introduced, with a mention of atoms undergoing multiple measurements to prepare them in a definite quantum state, referencing hyperfine splitting as an example.
  • A question is raised about the implications of different observers potentially obtaining different results from the same quantum system, referencing Zurek's proposal of quantum Darwinism and its relation to measurement outcomes.
  • A suggestion is made to search for "simultaneous eigenstate" for further clarification on the topic.

Areas of Agreement / Disagreement

Participants express differing views on the nature of measuring multiple operators simultaneously, with some suggesting that it is possible while others question the implications of such measurements. The discussion remains unresolved regarding the extent to which multiple operators can act on a quantum state at the same time and the interpretations of measurement outcomes.

Contextual Notes

Participants do not fully agree on the definitions or implications of simultaneous measurements and the nature of quantum states under multiple operators. There are references to specific experiments and theoretical frameworks that may depend on particular interpretations of quantum mechanics.

lucas_
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In a quantum state, if you use the position operator, it gives you position, momentum operator, momentum, Hamiltonian, energy.. can you give an example or all experiments done where a quantum state has 3 competitive operators acting on it.. I want to see the quantum state changing in between position, momentum and Hamiltonian.. and what is the biggest system that has been experimented on?
 
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Probably the experiment most students are familiar with, which "switches operators" (i..e changes what is being measured) at the quantum scale would be the Stern Gerlach experiment, where more than one S-G apparatus is used. Rotating the apparatus 90deg changes the operator from z-spin to y-spin.

Pretty much every experiment involves changing operators.
i.e. to do experiments on a particle in a box, first you have to get the particle in the box. The act of putting it in the box is a measurement of it's position - to "someplace inside the box" ...

In an experment, you don't think "I'll switch operators from momentum to hamiltonian", you think "I'll measure momentum then energy". You are just changing what you want to measure. Physically it involves changing the apparatus used to do the measurement.

Atoms have had something like 4 measurements - to prepare them in a definite quantum state: this is why you have 4 quantum numbers.
The experiments would involve hyperfine splitting for eg.
 
Simon Bridge said:
Probably the experiment most students are familiar with, which "switches operators" (i..e changes what is being measured) at the quantum scale would be the Stern Gerlach experiment, where more than one S-G apparatus is used. Rotating the apparatus 90deg changes the operator from z-spin to y-spin.

Pretty much every experiment involves changing operators.
i.e. to do experiments on a particle in a box, first you have to get the particle in the box. The act of putting it in the box is a measurement of it's position - to "someplace inside the box" ...

In an experment, you don't think "I'll switch operators from momentum to hamiltonian", you think "I'll measure momentum then energy". You are just changing what you want to measure. Physically it involves changing the apparatus used to do the measurement.

Atoms have had something like 4 measurements - to prepare them in a definite quantum state: this is why you have 4 quantum numbers.
The experiments would involve hyperfine splitting for eg.

And it's possible for two observers to have different operators and different results of the same quantum system at the same time?
Remember Zurek propose quantum Darwinism where the quantum system would produce only one outcome.. why does he need to propose this if experiment can show 2 results at the same time?
 
Google "simultaneous eigenstate".
 

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