The Josephson junction consists of a thin layer of insulating oxide material between two superconducting electrodes and is used mainly in measuring magnetic fields. In 1973, physicist Brian Josephson shared in the Nobel prize for physics “for his theoretical predictions of … those phenomena which are generally known as the Josephson effects”.
("The Nobel Prize in Physics 1973” https://www.nobelprize.org/prizes/physics/1973/summary/)
“At sufficiently low temperatures, electron-pairs pass through the insulating portion by quantum tunnelling.” (Penguin Encyclopedia 2006 - edited by David Crystal - 3rd edition, 2006 - ‘Josephson junction’, p.715)
Josephson, then a 22-year-old research student at Cambridge University, had a debate in 1962 with John Bardeen who had shared the 1956 Nobel Prize in Physics with William Shockley and Walter Brattain for the invention of the transistor. He would share a second Nobel prize in 1972 with Leon Cooper and Robert Schrieffer for their 1957 solution (the BCS theory) of the long-standing riddle of superconductivity.
(McDonald, Donald G. - “The Nobel Laureate Versus the Graduate Student” - https://pubs.aip.org/physicstoday/article/54/7/46/411592/The-Nobel-Laureate-Versus-the-Graduate-StudentJohn)
In an e-mail sent in the year 2000, Josephson offered the admonition: “Beware ye, all those bold of spirit who want to suggest new ideas.” His words apply to his younger self who, in 1962, was “bold of spirit” and “want(ed) to suggest new ideas”. What did he need to beware? Possibly – older scientists with established ways and conservative views … perhaps even his older, settled-into-tradition, self. Throughout history, older scientists have always argued against new ideas – and while many new ideas are indeed wrong, others which may seem to defy the laws of physics always win in the end. A quote attributed to Max Planck, the physicist who was a pioneer of quantum theory, says “A scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.” Those words may appear harsh but they remind us that elder scientists, even today and in future years, are – besides being vital teachers with much experience – subject to the conservatism which affects every person.
John Bardeen once commented –
"The idea of paired electrons, though not fully accurate, captures the sense of it."
(J. Bardeen, "Electron-Phonon Interactions and Superconductivity", in Cooperative Phenomena, eds. H. Haken and M. Wagner [Springer-Verlag, Berlin, Heidelberg, New York, 1973], p. 67).
Since paired electrons is not fully accurate, the BCS theory of superconductivity needs a further consideration. That factor would be to focus on the wave portion of quantum mechanics’ wave-particle duality instead of on particles.
This discussion suggests that both the combination of particles/antiparticles, and the quantum pressure of interacting gravitational and electromagnetic waves, are valid interpretations of a) the Hawking radiation emitted from black holes, and b) superconductivity not using the second half of duality i.e. paired electrons. Instead, the electron waves and wave mechanics of Louis de Broglie (1892-1987) are used – electron waves could maintain the superconducting circuit by travelling through the spaces between the atoms in the oxide material. This agrees with "Measurement of the time spent by a tunnelling atom within the barrier region" (https://doi.org/10.1038/s41586-020-2490-7) which says quantum tunnelling is not instantaneous - it's a result of particles' wave function.
Rodney Bartlett
Dear Professor Barlett,
Thank you for your interesting question.
As far as I am aware Josephson himself did not think of it in terms of "tunnelling particles." I think he had a deeper understanding, although the mathematics used was so abstruse and recondite, nobody could understand what he was talking about--- frankly speaking.
He said in one of his dissertations :
" It is clear that intuition is of no great help in understanding the supercurrent as a flow of Cooper pairs "
Cf. also
http://dx.doi.org/10.13140/RG.2.2.17687.60326
http://dx.doi.org/10.13140/RG.2.2.36133.63209/1
And
http://dx.doi.org/10.13140/RG.2.2.33962.75209/1
Dear Rodney Bartlett 1st we must define the electron. What is electron?
what internal structure it has and where to find them.
FYI: Electron never been observed to this date,
On the other hand, assumption, prediction is not science.
It is of course not particle-antiparticle pairs but two electrons with opposite spin (s wave) that are called
Cooper pairs. (From BCS theory).
The mechanism for attraction has always been sort of difficult, due to the electrostatic repulsion,
BCS theory proposes phonons or the underlying lattice of atoms. One electron pulls near polarized atoms
closer, that attract another electron. The radius of the pair may be large compared to interatomic distances.
The medium in effect converts a long ranged em repulsion, to a much shorter distance.
Juan Weisz "Particle/antiparticle pairs" refers to the interaction proposed by Stephen Hawking regarding black holes' Hawking radiation. I believe interaction of gravitational and electromagnetic waves creates pressure that can be interpreted as particles/antiparticles.
Rodney
Yes I believe such (different) pairs can play some role near the surface of Black holes.
Radiation is emitted from the recombination of these pairs.
The Feyman model of the Josephson junktion is the most transparent, probably.
It is usually solved approximately, but can be solved exactly, with very similar result, with a slight
difference in Josephson frequency.
Rodney Bartlett
Juan Weisz
"Particle/antiparticle pairs"
It depends on the way you look at it. Professor Weisz is right in terms of his conventional description viz. electrons forming Cooper pairs which then proceed around by a kind of laminar flow, but there are other ways of looking at it.
If you look at a Josephson Junction as an EPR pair tied in the barrier, then a description analogous to particle-antiparticle interactions ie. matter traveling both forwards and backwards in time, is possible, and yields the same result ; ie. j ~ Sin (phase difference).
Cf. https://fondationlouisdebroglie.org/AFLB-251/aflb251p027.htm
so we are back to a de Broglie type description as Professor Bartlett indicated.
I think that the matter traveling both forwards and backwards in time has something to do with the absolutely resistance-less property of superconductivity, as discussed here in connexion with an experiment proposed by Dolgopolov :
http://dx.doi.org/10.13140/RG.2.2.35349.60646/1
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