Talk:Nonclassical light

The whole section on Non-classicality of measurements is based on a recent work that does not fit into the rest of the article. This section cites of paper that is very recent whereas a whole body of work regarding non-classical light is missing. This section needs to be removed. I will do precisely that. Kanwarpreet Grewal 17:46, 1 April 2010 (UTC) —Preceding unsigned comment added by Kp grewal (talk • contribs) 17:45, 1 April 2010 (UTC)

What does "more singular than a Dirac Delta" mean? A Schwarz Distribution, perhaps? Is that even physically possible? (Collin237) —Preceding unsigned comment added by 32.178.251.251 (talk) 07:05, 23 March 2011 (UTC)

classical light
Classical light from natural sources is mostly incoherent, in particular thermal light is incoherent. The sentence that I deleted was not quite clear in its expression, but was very easily open to a reading that would say that thermal light is non-classical, which it is not. See for example Loudon, R. (2000). The Quantum Thoery of Light, third edition, Oxford University Press, Oxford UK, ISBN 0-19-850177-3, page 1, and Mandel and Wolf (1995) Chapter 13. It may be reasonable to replace the sentence that I deleted, but such a replacement would need to be more carefully and precisely worded than the one that I deleted.Chjoaygame (talk) 23:36, 5 December 2011 (UTC)

Very confusing
The article is extremely confusing: Firstly, the very first sentence of the lead says Nonclassical light is light that cannot be described using classical electromagnetism; its characteristics are described by the quantized electromagnetic field and quantum mechanics. So far so good, but the body – which we would expect to be no less exact than the lead – says A classical state of light is one in which $$\scriptstyle P(\alpha) \,$$ is a probability density function. If it is not, the state is said to be nonclassical. which makes $$\scriptstyle P(\alpha) \,$$'s being a pdf a necessary (but not necessarily sufficient) condition for the state of light to be nonclassical. But this condition says nothing (at least directly) about the electromagnetic field being quantized! So how is the general reader supposed to make a connection?

Second, the article declares, in the Glauber–Sudarshan P representation section, that It has been shown that the density matrix for any state of light can be written as:
 * $$\widehat{\rho} = \int P(\alpha) |{\alpha}\rangle \langle {\alpha}| \rm{d}^2 \alpha,$$

where $$\scriptstyle|\alpha\rangle $$ is a coherent state.

Now "any state", in science which is founded on logic, must mean "every state", which must include both coherent and incoherent states. Yet we are told that the expression $$\scriptstyle|\alpha\rangle $$ in the equation stands for a (certain) coherent state. Is this coherent state the "any state" we started with? If not, where is that state hiding?

While I don't know enough to fix these problems, I can at least remove the WP:Weasel Words "It has been shown that", since the article referred to should have the relevant sources. And will.

yoyo (talk) 05:26, 24 November 2017 (UTC)

Style of writing
The style of writing is as bad as the style of writing in the link. Written by another academic with ego-problems.