Randy Simon

Connecting the Future

As recently as 1986, most scientists doubted that they would ever find a room-temperature superconductor. But now such a discovery seems more and more likely. We can’t be completely sure someone will in fact develop a room temperature superconductor, particularly one that engineers can successfully shape into wires, circuit components, and other useful things. But suppose someone finds one, and suppose that in time scientists figure out how to synthesize it in useful forms and build devices out of it—say, in less than 25 years from now in 2011, in time for the celebration of the 100-year anniversary of Kamerlingh Onnes’ discovery of superconductivity. What technological marvels could we expect to see?

Miles of Wire

What is the most expensive piece of equipment you have used today? You probably used it in every room of your house. You used it at work, while you were shopping, and at play. Do you need another hint? It costs several billion dollars, but luckily you get to share it with quite a few of your neighbors. What is it? The electrical power system, a complex array of equipment that, for the most part, we can take totally for granted.

A Super Opportunity

We have traced the recent events that resulted in the discovery of superconductivity above 77 K, the temperature of liquid nitrogen, and we have examined the nature of these new compounds and the major challenges they present. Now we want to assess the impact that these new superconductors are likely to have in the future and try to understand why their discovery has triggered something of a revolution in the scientific world. In other words, why is high-temperature superconductivity such big news?

The Superconductivity Business

We have explored superconductivity as a science and as a technology, but superconductivity is also today a growing business. The tremendous publicity associated with recent laboratory breakthroughs in superconducting materials should not completely overshadow the fact that applied superconductivity supports a sizable worldwide industry.

Superconductivity and Quantum Mechanics

Up to this point we have been talking about relatively garden-variety phenomena: resistance, magnetic fields, and low temperatures. We are now ready to delve into some of the exotica of superconductivity. For this, we will need to know a little about quantum mechanics.

The New Superconductors

The discovery of high-temperature superconductivity has been hailed as one of the most important scientific events of the century. The amount of frenzied activity and excitement generated by the discovery supports this claim. Yet high-temperature superconductivity might be thought of as an enabling discovery rather than a groundbreaking discovery since superconductivity itself was already well known and its potential widely investigated before the latest breakthroughs. The immediate excitement surrounding the new superconductors stems from their potential for enabling old ideas to be brought to fruition. However, as we will see, the new superconductors may also enable a new revolution in scientific imagination.

No Resistance—No Magnetic Field

Superconductors intrigue us because they do many wondrous things, but they especially intrigue us because they do one thing perfectly: conduct electricity. Few things in nature exhibit true perfection but superconductors carry current with absolutely no resistance. Although, as we have seen, no measurement technique can distinguish between zero and some very small number, we have strong reason to believe that the resistance in a superconductor really is zero. This simple departure from ordinary electrical behavior is what makes superconductors truly super. But what constitutes ordinary electrical behavior?

The World of SQUID Magnetometry

Superconductors have earned their fame with their electrical properties, but so far they have earned their living with their magnetic properties. The electrical properties of superconducting wire will undoubtedly play a growing role in a number of future applications, but superconductivity has already become indispensable for advanced uses of magnetism. Superconductivity allows us to generate immense magnetic fields for a variety of applications in science, medicine, and industry. And at the opposite extreme, superconductivity also allows us to detect the presence of incredibly minute magnetic fields in the earth, under the sea, and within the human body. Sensing magnetic fields requires the techniques of magnetometry, and superconductivity provides the best magnetometers in the world.

The Era of Discovery

Superconductivity was the kind of unexpected discovery that scientists dream of all their lives. No one was looking for it, but the first person who even had a chance at finding it, did. No flash of insight or stroke of genius was needed. Instead the discovery required many years of hard work and tremendous progress in cryogenics, the science of refrigeration. As we will see, the early history of superconductivity and the history of cryogenics are inexorably intertwined.

Superconductors in Scientific Research

Since the 1950s, scientists have struggled to develop superconducting materials and devices for an impressively diverse array of applications. Some of these endeavors have already yielded practical results, while others still face years of further research. But as experts continue to work to develop commercial, industrial, and military applications of superconductivity, their colleagues from other scientific fields already reap some of the fruits of their labors. The effort spent to develop superconductivity has paid off with large dividends for purely scientific research. Particle physics, astronomy, microwave engineering, and many other fields have all benefited tremendously from the advantages of superconducting technology. Superconducting magnets, materials, and devices have all become a part of modern scientific experiments. In this chapter, we explore some of the work being performed at the frontiers of science—work whose progress depends upon novel applications of superconductivity.