Description From The Literature
A. Lupascu et al. give this description:
In quantum mechanics, the process of measurement is a subtle interplay between extraction of information and disturbance of the state of the quantum system. A quantum non-demolition (QND) measurement minimizes this disturbance by using a particular system—detector interaction that preserves the eigenstates of a suitable operator of the quantum system. This leads to an ideal projective measurement.
On the other hand, it has been argued that the usage of the term QND does not add anything to the usual notion of a strong quantum measurement and can moreover be confusing because of the two different interpretations of demolition in a quantum system (losing the quantum state vs. losing the particle). :
Read more about this topic: Quantum Nondemolition Measurement
Famous quotes containing the words description and/or literature:
“Why does philosophy use concepts and why does faith use symbols if both try to express the same ultimate? The answer, of course, is that the relation to the ultimate is not the same in each case. The philosophical relation is in principle a detached description of the basic structure in which the ultimate manifests itself. The relation of faith is in principle an involved expression of concern about the meaning of the ultimate for the faithful.”
—Paul Tillich (1886–1965)
“I did toy with the idea of doing a cook-book.... The recipes were to be the routine ones: how to make dry toast, instant coffee, hearts of lettuce and brownies. But as an added attraction, at no extra charge, my idea was to put a fried egg on the cover. I think a lot of people who hate literature but love fried eggs would buy it if the price was right.”
—Groucho Marx (1895–1977)