Direct Observation of Quantized Magnetic Flux in a Superconducting Hollow Cylinder with an Electron Interferometer

Abstract

curves for large Q, which must persist to some extent when noise is included, is the occurrence of a sharp rise in voltage ("instability") at a value of X considerably smaller than xmity.It should be noted that the parameter Q is independent of the area of the junction, depending only on the thickness of the junction, the temperature, and the materials involved. The parameter y, by contrast, is proportional to the area of the junction.We are grateful to Professor M. J. Stephen for posing this problem to us, and for discussions, and to Mr. F. Kardon for the numerical computations. One of the authors (V.A.) would like to thank the Bell Telephone Laboratories for hospitality during the month of January 1969 when this work was begun.

On the possibility of observing fluxons by transmission electron microscopy

“…The results obtained at present concern the observation of shadow patterns, or out-of-focus images, a t the edges of thick specimens (Blackman, Curzon and Pawlowicz 1963, Goringe and Valdrd 1964, Boersch, Bostanjoglo, Lischke, Niedrig and Schmidt 1966, Watanabe and Ishikawa 1967 Valdrd 1968, 1971) and of the detection of the presence of fluxons in bulk samples by means of interference techniques making use of biprisms (Wahll969, 1970, Lischke 1969, Boersch and Lischke 1970, Lischke 1970a. All the attempts to observe contraat effects due to fluxons in transmission electron microscopy have, however, so far failed ; this is probably due to the following facts : (i) no systematic and thorough attempt has been made because of the complexity and difficulty of the experiments ; (ii) the lack of theoretical data on the optimum working conditions ; (iii) a lack of experimental data on the properties of thin superconducting films.…”

The Aharonov-Bohm effect, controversial features of a long-standing debate

“…When an electron is passing along side a solenoid, a change in the energy of the electromagnetic field arises due to the overlapping of the magnetic field produced by that electron and the magnetic field of the solenoid. In analogy to the two-tube electrostatic experiment, a relative classical lag ∆L = eΦ/mv takes place for electrons (m=mass, v=velocity) passing on opposite sides of the solenoid thus producing exactly the same phase shift ∆ϕ = 2π∆L/λ, (λ is the electron wave length), of equation 1 revealed in the experiments described before (Möllenstedt & Düker, 1956;Fowler et al, 1961;Boersch et al, 1962;Möllenstedt & Bayh, 1962;Schaal et al, 1966;Lischke, 1969;Matteucci & Pozzi, 1978;Matteucci et al, 2003).…”

“…We recall only the most significant experiments to show the different strategies adopted to localize the magnetic field in the interferometer (for a review see Peshkin & Tonomura (1989), Olariu & Popescu (1985)). With reference to Figure 3, they are grouped as follows: i) the magnetic field S, produced by a ferromagnetic whisker or by a thin solenoid is located in the geometrical shadow of the biprism wire (Möllenstedt & Düker, 1956;Möllenstedt & Bayh, 1962), ii) a thin iron whisker (Schaal et al, 1966;Fowler et al, 1961) or, alternatively, a superconductor hollow cylinder (Lischke, 1969) replaces the biprism fiber and, at the same time, acts as a source of magnetic field, iii) the shadow region of the wire W in Figure 3 is vacuum coated with a thin ferromagnetic layer L (Fowler et al, 1961;Matteucci & Pozzi, 1978). The main rebuttal to all these experiments regards the fact that electrons move, respectively, through the stray field of the whiskers, solenoids, etc.…”

“…This experiment has been regarded as the best test to discriminate if the observed phase shift can be accounted for in terms of vector potential or of forces according to the Aharonov-Bohm's, the Liebowitz's or the Boyer's assertions respectively (Aharonov & Bohm, 1959;Liebowitz, 1965;Boyer, 2002). However, it is interesting to report the Boyer's considerations (Boyer, 2002) applied to the Lischke and Tonomura experiments with superconductors (Lischke, 1969;Tonomura et al, 1986): 'Experiments have been performed which attempt to shield the solenoid from the magnetic fields of the passing electrons. The persistence of the phase shift despite the presence of conducting materials shielding the solenoid has been interpreted as excluding the possibility of a phase shift based upon classical electromagnetic forces'.…”

Minimal Uncertainty in Momentum: The Effects of IR Gravity on Quantum Mechanics

“…Among the experiments for measuring Φ 0 which can be used to constrain α, paper [21] has found that the quantum of the magnetic flux trapped in a hollow superconductor is πh/e ± 4%. In this experiment, the area is S ≈ 3 × 10 −8 cm 2 , therefore, we will have…”