Talk:Quantum logic

message: A major motivation of quantum logic seems to be the fact that the propositions p, q and r in the second section can simultaneously be true, while in classical logic they can not. If this is truly the case, then a reference to an experiment where this, or a similar case, has been observed would be prudent. The lack of any references to experiment on this page is quite concerning. 
I know that it is a topic generally used by theorists alone, but reference to experimental papers is necessary for any page about physics, for which experiments have been conducted.
(Whole Oats (talk) 08:10, 21 November 2019 (UTC)
thread_title:  Reference to experiment 

message: Particularly, I think the statements  q = "the particle is in the interval [-1,1]" and r = "the particle is not in the interval [-1,1]" need to be clarified. What does it mean the particle is in interval [-1,1]? Does it mean that the amplitude of the wavefunction squared integrates to non-zero over this interval? Or does it mean that we have measured whether the particle is there or not and found it is in [-1,1]? 
The other thing is that p = "the particle is moving to the right" is also not clear. I imagine that this means that the particle is in a momentum eigenstate such that it is moving to the right. 
And one last thing, if (p and q) or (p and r) = false because "they assert tighter restrictions on simultaneous values of position and momentum than is allowed by the uncertainty principle" then it is clearly not true that the particle is in the particular momentum eigenstate and so p = false, which means p and (q or r) = p = false and thus (q or r) = (p and q) or (p and r). So distributive law is OK. Meznaric (talk) 12:26, 25 August 2009 (UTC)
thread_title: Introduction needs clarification

message: I've read a lot about this subject and it's always called "quantum logic", never "quantum reason".  For evidence, try some of the papers and books in the References for this article, starting with the Birkhoff--von Neumann paper cited at the beginning.  As the article notes, they called this subject "quantum logic" --- not "quantum reason".  --John Baez 11:01, 5 September 2007 (UTC)
thread_title: Why I renamed it "Quantum Logic"

message: "Quantum logic" first makes me think of the processing elements needed for Quantum computers.
David R. Ingham 05:48, 24 October 2005 (UTC)
replies: text: As used in the article, it's standard. --CSTAR 13:11, 24 October 2005 (UTC)
thread_title:  Disambiguation 

message: What happened to the revision history of this article? --CSTAR 15:39, 12 October 2007 (UTC)
replies: text: This appears to be the last version with the full edit history . Subsequently, the edit history got obliterated by what seems (to me at least) to be a copy-and-paste rename rather than a move.--CSTAR 16:40, 12 October 2007 (UTC)
thread_title:  Article history

message: When someone wrote…
    q = "the particle is to the left of the origin"
    r = "the particle is to the right of the origin"
    then the proposition "q or r" is true, so
… [s]he ignored the possibility that the particle is _at_ the origin, at least in the left/right sense of "at".  —Preceding unsigned comment added by 66.114.69.71 (talk) 20:15, 20 July 2008 (UTC)
thread_title:  Failure to consider all the possibilities 

message: The article begins
:In mathematical physics and quantum mechanics, quantum logic is a set of rules for reasoning about propositions which takes the principles of quantum theory into account.
and then
:Quantum logic can be formulated as a modified version of propositional logic.
And then an example of one of its properties is given. OK, so rule one:
:1. p and (q or r) ≠ (p and q) or (p and r)
:2. ...
Is rule number two?
:p and (q or r) ≠ (q or r) and p
What are the other rules please? I mean for fuzzy logic, for example, instead of a proposition just being true or false and having a value 1 or 0, it can have any value between 1 and 0, so to AND you take the smallest value of two propositions, and to OR you take the largest, and to NOT you just take the value of the proposition away from one. Simple. And that's all you need to know to start playing around with fuzzy logic.
So how do you do quantum logic?
--Vibritannia (talk) 12:23, 17 August 2008 (UTC)
thread_title: Can the Rules of Quantum Logic be Listed Simply?

message: I'm adding the category Systems of formal logic to this page. Seems its arguable whether it is or is not, but the fact that it's not clear seems to me to prove that inclusion is appropriate. FWIW.173.189.78.173 (talk) 21:42, 23 April 2015 (UTC)
replies: text: nLab agrees with you that quantum logic can be thought of as a kind of formal logic, so the formal logic cat seems reasonable to me. --Mark viking (talk) 22:58, 23 April 2015 (UTC)
thread_title:  Category - logic 

message: This article  seems to take a fair amount of effort to resolve linear logic as the right way to approach quantum logic. Here, the connection remains un-made.  It would be nice to resolve the two. 67.198.37.16 (talk) 22:04, 4 April 2016 (UTC)
thread_title:  speaking of ncatlab... 

message: When my attention was drawn to the example in this article purporting to show how quantum logic differs from boolean logic, my first impression was that it was just a poorly designed example, but after a while it struck me that it is false in a way which appears to have escaped the editors of the Routledge Encyclopedia of Philosophy and the editors of this wikipedia article: an unusual situation...
To elaborate, it's first worth emphasising that, as has been pointed out by others, the statements in the example are not purely logical propositions about definite facts. Rather, they are statements of this type: "if a measurement of the position of the particle were made, it would definitely be in [some specified region]" (and similarly with momentum measurements).  A problem is that these statements are such that it is impossible for the condition both in such a statement about position and a statement about momentum to be fulfilled (because such a measurement would invalidate knowledge about the other observable). But the flaw I discovered in the examples is worse than this.
The problem is a consequence of Fourier theory. For a function f with non-zero Lebesgue L2 norm (this always equals 1 for a wave function) if the set of points at which the function is non-zero is bounded, then the set of points at which the Fourier transform of that function is non-zero cannot be bound. The consequence of this is that the assumptions of the example can never apply to any particle: if the spatial wave function of the particle is such that it zero outside a bounded region, for probability of the momentum lying in any chosen bounded region is less than 1. I believe this conclusion follows from a version of the Paley-Wiener theorem and simple facts about entire functions.
As most people will realise, arguments about empty sets of examples are not ever going to enlightening, as they apply to nothing.  As a result, the example merely appears to be meaningful and has no genuine value.  This appears to be not at all a trivial fault of the example that can be fixed by designing it better, so I suggest that the example be removed from the article. Hopefully better examples can be found elsewhere. Elroch (talk) 23:07, 12 July 2016 (UTC)
thread_title:  Regrettably, the example from the Routledge Encyclopedia of Philosophy appears to have a fatal error