Brian D. Josephson
Photo curtsies of Brian D. Josephson's webpage:http://www.tcm.phy.cam.ac.uk/~bdj10
"Imagination is more important
than knowledge. Knowledge is limited. Imagination encircles the world."
(Albert Einstein) The words of a genius, to be considered by many, a man
who embodied those intrinsic values we call genius, and to display those
values at an early age. By these measures Brian D. Josephson also
complies to the word, genius, one of the youngest Nobel Laureates at just
34 in 1973, when he received the honor for work done at the age of 22.
The field of superconductors for many is fictitious dream, lived
out in laboratories, and chalkboards never to affect the layman.
Josephson's works have proved otherwise, his theories of tunneling between
two superconductors separated by a thin-insulating membrane may not be
understood to the common man, but nonetheless he enjoys the fruits of Josephson's
labor. Josephson's theories have nestled their way into the fabric
of science. New findings regarding suppositions of Josephson's work
continues today, providing a basis for the millennium's Nobel laureates,
in the fields of integrated circuits, in physics, and conducting polymers,
in chemistry. Josephson's work in the area of superconductors has
effect us profoundly, in the advancement and improvement of not only science,
but also technology on which the world runs today.
Born on Jan 4,
1940, to his parents Abraham, and Mimi Josephson, it would not be long
before his effect on the world would be evident.4 He enrolled
at Trinity College, University of Cambridge with ambitions to complete
his education in Physics.4 While an undergraduate he demonstrated
his promise, by writing a significant paper that criticized an earlier
paper, on the Mossbauer effect. The paper used the Mossbauer effect
to verify gravitational changes in the energy of photons, Josephson critiqued
it because it had not taken into effect the Doppler shifts accompanying
temperature changes.6 Thus was the character of Josephson,
not afraid to point out wrongs, while striving for perfection. He
then went on to complete his bachelor's at age 20, and continued research
with the Royal Society Mond Laboratory where in just two years he would
be working on what earned him the noble prize.2
From the point of 1962-1969, he would accomplish
his research as a Junior Research Fellow at Trinity College, til becoming
a Senior research fellow.4 During his research under the
direction of Brian Pippard; he attended a lecture by Phil Anderson, on
leave from Bell Telephone Laboratories, who introduced Josephson to the
concept of "broken symmetry" in superconductors. A concept where in the
laws of conservation are held together by separate laws dictating the conditions
under which the laws hold true.6 It was in the search for the
cause of this "broken symmetry", that Josephson under came the concept
of tunneling between superconductors. While transcribing the quantum-mechanical
equations for broken symmetry, he arose with an idea. Using the findings
from earlier work by M. H. Cohen, L. M. Falicov, and J.C. Philips, who
had calculated the current flowing in a "superconductor-barrier-normal
metal system," Josephson extrapolated the data to a "superconductor-barrier-superconductor
system."3 This junction, made up of an thin (less than
20 angstroms thick) oxide layer between two conductors, incorporated findings
from L. Esaki and I. Giavier, his future fellow Nobel Laureates,
on tunneling: a phenomenon by which electrons functioning as radiated waves
can penetrate solids.4 All of these findings cumulated
into the theory that there could be a flow of current through
which the insulating layer without the application of a voltage, and that
if a voltage was over imposed that the voltage would stop give rise to
voltage steps, in other words the voltage occilated at a frequency directly
proportional to the frequency.6 This is what we now know as
the Josephson effect.
Learning of this discovery, Pippard suggested that Josephson go ahead and
try to see the supercurrent himself. However the results weren't promising,
so discouraged by the findings, he planned to include the experiments in
his thesis entitled, "Two Unsuccessful Experiments in Electron Tunneling
Between Superconductors."6 But his advisor, Phil Anderson
recognized that the electrical noise that had interfered with observations
and cooperated with John Rowell at Bell Telephone Laboratories to prove
that the inhibiting factor was the proof in the pudding.6 With
the confirmation of tunneling between superconductors the earlier BCS theory
was confirmed in the behavior of superconductors.
Josephson has remained
at Cambridge throughout his scientific career except during 1965-6 when
he served as a research assistant at the University of Illinois, Urbana.6
He returned to Cambridge as assistant director of research, where in 1972
he was appointed reader in Physics, and two years later appointed professor.6
He continued his research in superconductivity and its critical phenomena,
and received many awards including the New Scientist Award, the Research
Corporation Award, and was elected a member of the Royal Society in 1970.6
Though one would
be hard pressed to find a citizen who recognizes Josephson's name, he has
helped bring technology to where it is today. Josephson's findings
have found their way permanently into society. In the 1980's researchers
at International Business Machines Corporation had assembled experimental
computer switch structures that would permit switching speeds to increase
from 10 to 100 times faster that those possible with conventional silicon-based
chips, increasing data processing capabilities significantly.
An example of this is
the logic device, made up of three junction SQUID (superconducting quantum
interference device), that operates in the a zero voltage state, giving
it switching times of 10 picoseconds or less. 3 The Josephson
effect has taken an established role in the realm of Standards in laboratories.
The significance of Josephson’s effect is manifests itself in measurement
of the fundamental constant ratio e/h. Both of these areas have achieved
new precision levels because of Josephson's efforts. When a Josephson
junction is radiated with microwaves of a frequency f, constant-voltage
steps are induced on the current-voltage characteristic at voltages nhf/2e,
where n is the integer.3 Precise measurements of the voltages
at which the steps are induced by a known frequency have lead to the most
accurate determination available of e/h. Furthermore, the internationally
accepted primary standard for the volt is now maintained by these voltage
steps at the United States National Institute of Standards and Technology.3
In other words the findings of Josephson have brought new levels to the
science of precision, for example electromagnetic radiation detectors.
Investigation continues into the use of Josephson junctions as sensitive
detectors: of microwaves, millimeter, and sub millimeter electromagnetic
radiation. All devices of operation have been investigated, including
square-law detectors, mixers, and parametric amplifiers. Of these,
only the parametric amplifier shows much promise, where in the frequency
of microwaves the sensitivity of this device is second only to that of
the maser.5
Some would think
achieving such great feats so early in life would lead one to retire, having
accomplished a goal, but not so for Josephson. In the years slightly
before, and following the achievement of the Nobel Prize, Josephson’s curiosities
lead him to different paths. His gaze turned to the relevance of Eastern
mysticism to scientific understanding.4 He now looks toward
the relationship between the scientific and inner experience. In
1980, along with V.S. Ramachandran, he published an edited transcript of
the 1978 international symposium on consciousness at Oxford entitled, "Consciousness
and the Physical World." He continues his work today, as head professor
of the Mind-Matter Unification Group at Cambridge he recently released
a paper on “The Paranormal: The Evidence and its Implications for the Consciousness.”
1
Josephson’s work has
influenced today’s science like few other have. His contributions
have dramatically affected and invented new ways in which applications
for superconductors can now be used. From the areas of retaining scientific
standards to everyday application in computers and the technology of today
Josephson has made an impact. Thought the concepts behind the technology
cannot be explained in normal terms, but use the complex conditions of
quantum mechanics, doesn’t stop the influence of Jospehson’s findings.
He has influenced the world enormously already, an will surely in the years
to come.
Works Cited
1 “Brian D. Josephson.” Online. Internet. 3 Dec 2000. Available
http://www.tcm.phy.cam.ac.uk/~bdj10/psi/tucson.html
2 Miller, David, Ian, John, Margaret. “Dictionary of Scientists.” University Press, Cambridge. © 1996 p.115
3 “Superconductivity.” McGraw-Hill Encyclopedia of Science and Technology. Vol. 17. 7th Ed. © 1992. p. 663-52.
4 “Josephson, Brian D.” Encyclopedia Britannica. © 1999-2000.
5 “ Low-Temperature Phenomena.” Encyclopedia Britannica. © 1999-2000.
6 Magil, Frank N. Nobel Prize Winners of Physics. Vol 3:1968-1988. © 1989 p.1039-1043.
7 2000. Available WWW http://www.almaz.com/nobel/nobel.html
If
you have comments or suggestions, email me at sghussai@ole.augie.edu
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