Talk:Aharonov–Bohm effect

message: The article states that "The underlying mechanism is the coupling of the electromagnetic potential with the complex phase of a charged particle's wave function".
This requires a citation. Who says so and in what textbook or peer reviewed publication?
Aoosten (talk) 00:33, 10 December 2013 (UTC)
replies: text: You will be hard pressed to find a text that doesn't say it. Xxanthippe (talk) 04:47, 10 December 2013 (UTC)
thread_title: Interpretation

message: I have heard that the magnetic monopole business which is stated is far from being accepted by the majority of physicists.
Is there any proof that this magnetic monople stuff has any existence ?
Honestly I doubt.  —Preceding unsigned comment added by 84.97.205.102 (talk) 21:28, 4 November 2007 (UTC)
replies: text: The monopoles described in this article are quasiparticles that crop up in condensed-matter physics quite often due to separation of equal but opposite magnetic charges, connected by a finite-width flux tube. They are thematically similar to 'true' monopoles but are in no way controversial. They cause a stir from time to time when someone reports experiments regarding Dirac strings as indicative of the discovery of real monopoles. A similar kerfuffle tends to occur when research regarding spin-charge separation is taken to indicate that electrons are composite particles. Note: I am not a licensed quantum mechanic. Eutactic (talk) 06:59, 4 June 2010 (UTC)
thread_title: Help & Warning !

message: It is NOT TRUE that a long solenoid does not cause a magnetic field outside of itself. There is a tiny right-hand field, as well as a (comparatively) large up-down field (description is very bad, but try to understand).
:An ideal solenoid would indeed have no magnetic field outside of the solenoid.  This is of course impossible to acheive in real life.  The original experiment didn't even use a solenoid so far as I know, but rather a thin whisker of magnetic material.  In theory the ideal AB experiment would have zero magnetic field outside, but here we just get into the experimental practicalities of negligible versus zero.  --Laura Scudder | Talk 20:09, 18 August 2005 (UTC)
thread_title: long solenoid

message: Could someone add something which explains this effect in layman's terms. I have a strong sense that this could have immense siginifance but as soon as the technical terms and algebraic equations turn up I'm left in the dust. Please could someone elucidate for a non-specialist, arts-background person like me? :-) ThePeg 28.7.2006
:Another, in some ways better, summary is available at http://www.tau.ac.il/~quantum/publicat/topo-effects.html .  I am working on gauge fixing right now; perhaps when I am at a good stopping point there I will try to improve this article.  Cheers, Michael K. Edwards 03:23, 20 October 2006 (UTC)
replies: text: One way to do this is to express the interference effect between the two electron paths in the solenoid/double-slit setup as the flux of the magnetic field across any surface bounded by the two paths. The flux of the magnetic field is a gauge-invariant quantity - in fact, it can be measured independently by Faraday's Law of Induction. The Aharonov-Bohm effect is not so different after all from the electric field induced on a closed loop of wire going around a solenoid when the current on the solenoid is varied. The time-rate of change of the AB phase is Faraday's electromotive force. Miguel (talk) 12:33, 4 January 2011 (UTC)
thread_title:  Help! 

message: I am currently trying to understand this phenomena, starting out from the example given in chapter 18 (By McEuen) in Kittel's Introduction to Solid State Physics, 8th Edition. This Wikipedia article does not seem to help very much, unfortunately. More examples would help - also external links would help, not just references to articles.  —Preceding unsigned comment added by 130.225.102.1 (talk) 12:01, 25 April 2008 (UTC)
replies: text: Classically, the E and B were "fields" and the φ and A were "potentials", so no confusion there unless you want to really split hairs with the more general meaning of "field" as "any scalar, vector or tensor-valued function varying across space and/or time". Miguel (talk) 14:33, 4 January 2011 (UTC)

text: The Aharonov–Bohm effect, sometimes called the Ehrenberg–Siday–Aharonov–Bohm effect, is a quantum mechanical phenomenon by which a charged particle is affected by electromagnetic fields in regions from which the particle is excluded.
Now what do they mean by unlinked term, electromagnetic fields?  I guess they mean the E and B fields.  But I have to guess, which is not a good sign. --Michael C. Price talk 11:02, 16 August 2009 (UTC)
thread_title:  More examples needed 

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thread_title:  Copyright problem removed 

message: It would be great if somebody could work out specific examples,
with an actual model for B(r)/E(r), resulting A(r) and the phase change, for both the magnetic and particularly the electric effects. 
The present description is not immediately obvious for the magnetic case, and look plain impossible for the electric effect! 
Specifically:
1) Electric case:
How can one "construct a situation" where the electric field (grad phi) is zero everywhere along a closed loop (the too paths with common start and end), yet the electric potential (phi) is different at different points along the paths??? The description of the speicific experiments looks quite cryptic, but whatever they were I doubt they fit the present description of the electrical AB effect, which is essentially trying to say one can make a=b and a!=b at the same time.
2) Magnetic case:
To begin with, the statement that "ideal solenoid" has zero field outside of it is puzzling:
shouldn't an ideal cylindrical solenoid have dipole-like field infinitely far away? Now, I'm OK with assuming that the field is zero either because it can be ideally shielded, or that it is zero because the solenoid in between the two paths is actually  toroid. But then there appear fields  in opposing directions, so I don't see as totally obvious that their contributions do NOT cancel! Say, if you say calculate the net flux across any cross-section you will get zero. 
The only more or less obvious scenario I can think of is an ideal toroid solenoid with one path going through the center of the torus and the other fully outside the torus -- but even then the field is non-zero due to the net current flowing along the _outer_ radius of the torus! Besides, this is not what the article presently describes.
So if anyone could specify a particular model geometry, with clear behavior of magnetic field both inside and outside the plane of drawing (NOT with magnetic field lines disappearing into we don't care where), and show why within a specific gauge A(r) becomes nonzero along the paths  -- that would greatly help!!!  —Preceding unsigned comment added by 64.149.234.79 (talk) 09:34, 23 October 2010 (UTC)
thread_title:  An explicit example desirable; confusing description at present 

message: These paragraphs from the introduction are rather confused. I intend to rewrite them and I copy them here for discussion in case my version is later challenged:
:The Aharonov–Bohm effect is important philosophically: the "classical" approach to physics is completely based on Newton's equation F = ma; so for centuries physics was all about forces, and the electric field E and the magnetic field B can be used to calculate the force on a charged particle. However, force is not a valid 4-vector in special relativity. Because of this, in special relativity it is difficult to calculate with forces. Since the E and B fields are force fields, they are also not valid special relativity 4-vectors: one can easily see this because the E and B fields one calculates or measures depend on velocity. Similarly in quantum mechanics particles are represented as waves, and it's difficult to describe how waves interact with forces. So in quantum mechanics one prefers to work with potential energy. In relativistic quantum mechanics, including quantum electro-dynamics, it's difficult to even speak of a force.
:When formulating electrodynamics, one may choose to use either E and B, or the electric potential Φ and the magnetic (vector) potential A. Together, these quantities form a valid special relativistic 4-vector. However, this 4-vector is not uniquely determined, one may always add certain scalar or vector functions, derived from so-called gauge functions, to this 4-vector, and the resulting E and B fields will not change. For a long time people wondered if the A field was fundamental, even though it cannot be uniquely determined, or if it was just a mathematical trick.
The conceptual issues around the AB effect are not fundamentally about relativity, as the Aharonov-Bohm effect is observable experimentally at ordinary speeds and can be easily formulated in terms of the nonrelativistic Schrödinger equation.
The conceptual issue is properly about forces, fields, potentials and gauge invariance. I am editing accordingly. My first version is
:The Aharonov–Bohm effect is important conceptually because it illustrates the physicality of electromagnetic potentials whereas previously it was possible to argue that only the electromagnetic field was physical and the electromagnetic potential was a mathematical construct (being non-unique, in addition to not appearing in the Lorentz Force formula). The non-uniqueness of the electromagnetic potential is a manifestation of electromagnetic gauge invariance, with the electric and magnetic fields and forces being gauge invariant and therefore directly observable in principle. The complex phase of the electron wavefunction is coupled with the electromagnetic potential and the Aharonov-Bohm effect can be illustrated by interference experiments.
If that is not clear enough it can be developed in the body of the article and explained a little better in the intro. It also needs to be wikified. Miguel (talk) 21:51, 1 January 2011 (UTC)
replies: text: or more precisely: a certain gauge invariant quantitiy, ΦB
from the introduction.  It has bothered me for awhile and no one had clarified it.  Do you agree? -- cheers, Michael C. Price talk 08:07, 2 January 2011 (UTC)

text: Yes, I don't know what that was about. Miguel (talk) 11:08, 4 January 2011 (UTC)
thread_title:  Philosophical issues not about relativity but about gauge invariance. 

message: I imagine the case that the solennoid is very far from the two slit.
In that case, Aharonov-Bohm effect continues or disappears?.
Custum quantum theory does'nt deal with the that case. .
Qauntum theory does'nt consider the distance between the solenoid betweeen thw slit.
If one knows the answer, contact me, mrhun@hanmail.net  — Preceding unsigned comment added by Younghun park (talk • contribs) 03:20, 5 October 2011 (UTC)
replies: text: The case of the solenoid far from the slit isn't interesting because then the particle can pass through the solenoid.  The cool thing about the effect is that the particle responds to changes in a region it can't pass through.  — Laura Scudder | talk 21:02, 9 November 2012 (UTC)
replies: text: Tthe whole point of the experiment is that the walls of the solenoid are made thick and dense enough that they are effectively impenetrable by electrons, so regardless of the distance the particles cannot pass through the solenoid.  What matters is whether they can pass around the solenoid by two different paths, and in principle this could occur regardless of the distance from the slits to the solenoid.  — Steven G. Johnson (talk) 16:35, 10 November 2012 (UTC)
thread_title:  The case that the solenoid is far from the two slit 

message: See here why. Count Iblis (talk) 18:07, 28 October 2011 (UTC)
replies: text: Very interesting.  Tell me if I have understood this: the magnetic AB effect is caused by a temporary rotational differential in the solenoid, caused by the passage of the electron, which induces an entangled B field outside the solenoid? This entanglement vanishes after the electron has passed.-- cheers, Michael C. Price talk 06:09, 29 October 2011 (UTC)
thread_title:  Article is misleading 

message: This article could use a few more diagrams. Please see here for some. I'll draw another soon for the double-slit interference of an electron beam around a solenoid, a separate one complete with a "magnetic wisker" (assuming that's the correct name for the thing to deflect the beam and shift the interference pattern...). Thanks, M∧Ŝc2ħεИτlk 06:34, 9 May 2013 (UTC)
thread_title:  Diagrams? 

message: There exists literature which contests the interpretation of the Aharonov-Bohm effect present in this article. I believe we should edit the article to reflect this.
:[T]he persistence of the Aharonov-Bohm phase shift when the solenoid is surrounded by a conductor does not exclude a classical force-based explanation for the phase shift. At present there is no experimental evidence for the Aharonov-Bohm effect.Timothy H. Boyer, Does the Aharonov-Bohm effect exist? Foundations of Physics, Vol. 30, No. 6, 2000
The author argues that there is plenty of experimental evidence for the phase shift itself but zero evidence for the quantum topological nature of the phase shift. The major argument is that the velocity fields of passing electrons penetrate even excellent conductors and that an ohmic conductor does not screen out the magnetic field of a passing charge; in fact, the author argues that the time-integral of the magnetic field of the passing charge in the material is invariant of the conductivity of the material. 
See also Jackson chapter 14 -- velocity fields have no characteristic skin depth to them as they are not radiation fields. Destatiforze (talk) 19:50, 4 September 2016 (UTC)
thread_title:  A classical approach to the Aharonov-Bohm phase shift 

message: The explanatory text and equation should reference delta potential where appropriate, to correspond to the delta phase.  As it stands, it looks as though there is a known 0 reference for V. Jim Bowery (talk) 03:51, 15 September 2020 (UTC)
thread_title:  Electric Effect 

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thread_title:  External links modified (January 2018) 

message: There is some important research reported in (secondary source) https://phys.org/news/2019-09-exotic-physics-phenomenon.html ("Exotic physics phenomenon is observed for first time") and originally published in Science (    DOI: 10.1126/science.aay3183 Science Vol. 365, No. 6457).  I suppose, how-ever, we will have to wait a while for secondary material to pile up before this is included, given the rancour seen on this talk page. Kdammers (talk) 02:15, 6 September 2019 (UTC)
replies: text: Correct. New material will need to be supported by multiple, reliable and independent sources. Xxanthippe (talk) 02:21, 6 September 2019 (UTC)
replies: text:  Here's a start: https://scitechdaily.com/exotic-physics-phenomenon-involving-time-reversal-observed-for-first-time/ Kdammers (talk) 01:11, 9 September 2019 (UTC)
replies: text: There is a long way to go. Let's wait for the citations WP:NOTNEWS. Xxanthippe (talk) 02:40, 9 September 2019 (UTC)
thread_title:  Very significant recent research results