Indiana University       Research & Creative Activity       September 2000 • Volume XXIII Number 2

N e w D i r e c t i o n s in Applied Physics

by J. Timothy Londergan

Historians reviewing the scientific and technical developments of the twentieth century have dubbed it “The Physics Century.” During the last century, developments in physics led to revolutionary advances in our understanding of the laws of nature, which in turn created entirely new subfields of study. The field of atomic and molecular physics, for example, was made possible by the advent of relativity theory and quantum mechanics, which were discovered at the turn of the century. Likewise, the field of nuclear physics was founded in the early decades of the past century, when the fundamental constituents of thw atomic nucleus were discovered and studied.

Physics dominated our past century for a second reason as well—the development of applied technologies that have revolutionized both our economies and our daily lives. The study of electrons in solid-state systems opened up a tremendous range of applications, culminating in the development of transistors, lasers, computers, and the modern electronics industry. Our understanding of the biological effects of radiation led to modern imaging systems, such as CAT scans and MRIs, and to the use of radiation to combat disease and cancerous tumors.

J. Timothy Londergan, professor of physics at IU Bloomington and director of the IU Nuclear Theory Center, stands outside Swain Hall West, where the IU Bloomington Department of Physics is located. Photo Tyagan Miller

Recent advances in physics suggest a new round of technological breakthroughs. University-based research in physics today has a renewed focus on applied physics, complementing the “pure” research so dominant in the past. Modern applied physics research is characterized by interdisciplinary work. New areas, particularly biophysics and medical physics, have led to exciting collaborations between physicists and scientists in other disciplines. As massive corporate R&D facilities, typified by institutes such as IBM and AT&T Bell Labs, have downsized, the opportunities for university scientists to explore new directions in applied research have increased.

While continuing its strength in traditional areas of inquiry such as nuclear, high-energy, and condensed matter physics research, IU also has undertaken significant new research efforts in applied physics. This issue of Research & Creative Activity magazine highlights some of the people and resources involved in five broad categories of cutting-edge applied physics research:

Charged particle beam radiation therapy. The challenge of radiation therapy is simple—to kill cancerous cells without damaging healthy ones. Electrically charged particles such as protons have many advantages over the photons used in conventional therapy, because protons and photons interact quite differently with matter. Proton beams can also be used to treat noncancerous diseases. The Midwest Proton Radiation Institute, under development at IU Bloomington, will serve as a regional center for research and treatment, using protons from the IU Cyclotron Facility to provide the charged particle beams.

Biophysics. The rapidly growing field of biophysicsrepresents a relatively recent branch of applied science with strong cross-disciplinary overlap between physics, biology, and materials research. The growth in this field has been sparked by the development of new techniques that access extremely small-distance scales. This allows physicists unprecedented control of DNA and protein samples, down to the level of individual molecules. For some time, IUPUI has had a productive biophysics group, which uses experimental physics techniques to investigate biological processes. IUB has just created a research group in biophysics that is expected to grow significantly in the next few years.

Spin electronics. In traditional electronics, electrons are controlled through measurement of their electric charge. Recent research uses the electron’s intrinsic “spin” to determine the output signals. Because the electron’s spin determines the magnetic properties of materials, these new “spintronics” systems may herald the development of a wide variety of magneto-electronic and magneto-opto-electronic devices. Such devices are already in use in high-density computer disk drives and may pave the way for revolutionary changes in computer random-access memory devices. These advances also provide the research community with new ways to study the dynamics of electrons moving through materials.

Radiation effects on semiconductor devices. Nearly all modern electronic devices depend on semiconductors for their operation. But when semiconductors are subjected to intense radiation fields, they can break down from the radiation damage. With the continued increase in the density of components on silicon chips, electronic devices in next-generation supercomputers and commercial aircraft may be especially susceptible to disruption by radiation. This potential for breakdown is a particular concern in military and space applications, especially devices that are scheduled to reside on the International Space Station. In collaboration with NASA, several academic centers, and various commercial suppliers, the IUCF is conducting a significant research program aimed at understanding radiation effects, using accelerator beams to simulate naturally occurring fields.

Quantum optics. Recently, there has been great interest in the possibility of “quantum computing.” The goal is to produce computers that operate by manipulating the vast amount of information contained in the wave functions of quantum systems. If this information can be harnessed for practical computations, then, in principle, quantum computers could solve problems that cannot be calculated with present-day technology. To make quantum computing a reality, methods must be developed to store, transport, and manipulate this information. In this issue, we describe a research program underway at IUPUI that is investigating the use of optical beams to encode and transport quantum information. Although the technical obstacles are formidable, the potential applications of such technology are truly revolutionary.

We can highlight here only a handful of the many applied physics research projects going on around IU. Even nonapplied research programs in physics frequently produce applied spin-offs as by-products of the fundamental research. Particle detectors, an integral component of nuclear and high-energy physics research, are an excellent example. Many new developments in particle detectors find their way into medical imaging devices. These new detectors will soon replace the traditional photographic film used for X-ray and MRI imaging, as described in an article in the September 1999 issue of Research & Creative Activity. Nevertheless, even the partial review provided in this issue offers exciting examples of the synergy between fundamental research and applied technology.

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