CPEM 2004
Conference on Precision Electromagnetic Measurements

Wednesday

Plenary Session

"Quantum Computation and raising Schrödinger's cat"
D Wineland

Two discrete energy levels in quantum system, such as an atom, can be used to store a bit of information. However, quantum systems can also exist in superposition states, thereby storing both states of the bit simultaneously. This property potentially leads to an exponential increase in memory and processing capacity. It would enable a quantum computer to efficiently solve certain problems, such as factorizing large numbers, which may be intractable on a classical computer. Actually building a useful quantum computer is an extremely daunting task due to the necessity of overcoming decoherence. Nevertheless, in the near term, the principles of quantum information processing may find important applications in metrology. A quantum computer would also realize a mesoscopic version of "Schrödinger's Cat," a bizarre situation where a cat could be simultaneously dead and alive. A number of physical systems are currently considered for building a quantum computer; we focus on examples using atoms, but also discuss other possible implementations.

"Recent Development of Terahertz Wave Time-Domain Technology"
X-C Zhang

Terahertz (THz) radiation, which occupies a large portion of the electromagnetic spectrum between the infrared and microwave bands, offers innovative imaging and sensing technologies that can provide information, which is not available through conventional methods (i.e. microwave and X-ray techniques.) Recently, governmental supported THz wave related fundamental research in science and application emphasized technology development has increased substantially. As THz wave (T-ray) technology improves, we believe new T-ray capabilities will impact a range of interdisciplinary fields, including: communications, imaging, medical diagnosis, health monitoring, environmental control, and chemical and biological identification. This is particularly crucial for identifying terrorist threats in homeland security (three to five years), and medical diagnosis or even clinical treatment in biomedical applications (five to ten years).

T-rays offer the opportunity for transformational advances in defense and security. Recent work in our laboratory, for example, shows that T-rays have promise as a means of examining an unidentified organic powder inside an unopened paper, cardboard, or plastic container. We also are looking at T-ray spectroscopy as a method of identifying explosive compounds. Unique features in the THz spectra of these materials have been identified. A THz wave can easily penetrate and inspect the insides of most dielectric materials, which are opaque to visible light and low contrast to X-rays, making T-rays a useful complementary imaging source in this context. In addition, we have demonstrated the outstanding sensitivity of our T-ray detection systems, which can measure monolayers of certain compounds, including water.

T-rays have several advantages over other sensing and imaging techniques. While microwave and X-ray imaging modalities produce density pictures, T-ray imaging also provides spectroscopic information within the THz frequency range. The unique rotational and vibrational responses of biological materials within the THz range provide information that is generally absent in optical, X-ray and NMR images.

Examples of such applications to the recognition of terrorist threats include the utilization of terahertz spectroscopy in the identification of biomaterial, which has fingerprints in the terahertz range, and remote sensing and imaging of explosive targets. I will also report how THz wave imaging contributes to NASA programs in the detection of defects in space shuttle insulating materials, which will be used before the next launch in Sept. 2004