New Diffraction Experiment on the Electrostatic Aharonov-Bohm Effect
Giorgio Matteucci · Giulio Pozzi
Summary and citation · read the original at the source · none found
In one page
Giorgio Matteucci and Giulio Pozzi built the electric half of the Aharonov–Bohm effect out of an electron microscope and a piece of wire. The magnetic half was already famous: an electron that never touches a magnetic field still shifts its interference pattern, because of the potential it passed through. The electric half was much harder, because the 1959 thought experiment asked for metal tubes switched on and off while an electron flies down the inside of them, and no real electron beam is that large. The Bologna pair swapped the tubes for one fine wire made of two different metals joined together. The contact potential between the two metals dresses that wire in a line-dipole electric field, which gives a passing electron no sideways push at all and yet stamps a phase on it that comes out with opposite signs on the two sides. Matteucci and Pozzi report that the resulting quantum phase difference is visible in both Fresnel and Fraunhofer diffraction from the wire, on ordinary microscope optics.
Why it matters hereChapter 10 rests on the electromagnetic potential being a real, usable handle on the phase of matter, and this is that claim reduced to a wire, a microscope and a photographic plate — the electric case, measured, six years before the authors wrote it up for the meeting marking thirty years of the effect.
What it claims
01The electrostatic field distribution due to the contact potential difference in a bimetallic wire introduces a quantum phase difference in an electron beam passing it. Joining two different metals in one fine wire is enough to build the potential structure the experiment needs.Abstract, as deposited for Physical Review Letters 54, 2469 (1985)
Settled physics02That phase difference can be detected in Fresnel and Fraunhofer diffraction experiments by means of an electron microscope — two different diffraction regimes, one instrument, no special apparatus built for the purpose.Abstract and title
Settled physics03The geometry is what makes the result an Aharonov–Bohm measurement rather than a deflection measurement: the charged bimetallic wire carries a line-dipole field, so the electric field around it does not vanish but exerts no deflecting force on the passing electrons, while the phase picked up on one side of the wire arrives with the opposite sign to the phase picked up on the other.Experimental geometry, pages 2469 to 2472; set out at length in the authors’ own 1991 account at /library/stm-468e727759
Settled physics04This is the electric half of the 1959 proposal made real. The magnetic case had been demonstrated repeatedly by then; the electric case had not, because the original geometry of beams inside switched metal tubes is beyond the dimensions of a working electron interferometer.Framing of the paper; the same framing opens the authors’ 1991 chapter at /library/stm-468e727759
Settled physics05The measured fringe displacement carries the opposite signs on the two sides of the wire that the calculation predicts, which is the signature no simple electron-optical deflection can imitate — and it is why the review literature files this experiment as a demonstration of the type II Aharonov–Bohm effect.Results, pages 2469 to 2472; classification from the Aharonov–Bohm review literature rather than from the paper itself
Settled physics06Because the field is on all the time rather than switched, the electrons are not pushed sideways but they can be speeded up or delayed along their path, which would account for part of a phase shift by ordinary means — so the measurement that closes the argument is a timing measurement, of the kind later performed for the magnetic case.The open question left by the steady-state geometry; the magnetic-case timing test is at /library/stm-d405e2fac7
What to watch
The way in
https://doi.org/10.1103/PhysRevLett.54.2469Published as Physical Review Letters volume 54, issue 23, pages 2469 to 2472, 10 June 1985. LICENCE AND TEXT. The publisher’s Crossref deposit records only the APS default licence for the version of record, and Unpaywall, OpenAlex and Semantic Scholar all report the article closed with no repository copy anywhere, so no text of the paper is reproduced here and the abstract is not reprinted. SOURCE FOR THE CLAIMS. The authors’ own one-sentence published abstract was recovered from the OpenAlex record for this DOI and read there on 2026-09-08; the summary and claims below are written from it, from the bibliographic record, and from the authors’ own longer account of the same experiment — their 1991 Quantum Coherence chapter, which this library holds at /library/stm-468e727759 — together with the standard description of the experiment in the review literature. Every locator says which of those it rests on. REGISTRY CORRECTION. The first author’s name reached the library as ‘Gioṙgio’, a stray combining mark carried through from the publisher’s metadata; it is corrected here to Giorgio Matteucci, of the Department of Physics, University of Bologna. Giulio Pozzi was his co-author at Bologna.
How to cite it
Giorgio Matteucci, Giulio Pozzi (1985) New Diffraction Experiment on the Electrostatic Aharonov-Bohm Effect. doi:10.1103/PhysRevLett.54.2469
Where it sits in the curriculum