# What is Faithful Measurement?

What is ''faithful measurement'' in Quantum Mechanics exactly. I have seen this expression in Kochen-Specker Theorem.

## Answers and Replies

.Scott
Homework Helper
To quote wiki (http://en.wikipedia.org/wiki/Kochen–Specker_theorem:
For such more general theories the KS theorem is applicable only if the measurement is assumed to be a faithful one, in the sense that there is a deterministic relation between a subquantum element of physical reality and the value of the observable found on measurement.
In this case "subquantum element" is a supposed "hidden value".
Since KS argues against hidden values and hidden values are not how most physicists interpret QM, it's probably not correct to say that "faithful measurement" is part of QM - only as part of the study of QM.

Last edited:
• vanhees71 and omidaut
To quote wiki (http://en.wikipedia.org/wiki/Kochen–Specker_theorem:
In this case "subquantum element" is a supposed "hidden value".

thanks for your reply. but again I cannot understand the exact definition of faithful measurement :/

.Scott
Homework Helper
It simply means that the measurement is the result of a specific (non-stochastic) function of some observable.

• omidaut