Condensed matter physics (CMP) is the fundamental science of solids and liquids. It also deals with states intermediate between solid and liquid (e.g. liquid crystals, glasses, and gels), with dense gases and plasmas, and with special quantum states such as superfluids that exist only at low temperatures.

Of all the branches of physics, condensed matter has the greatest impact on our daily lives through technological developments. For example, the invention of transistors and semiconductor chips have led to the widespread use of a variety of electronic appliances, telecommunication devices (fax, cellular phones, and modems), and personal computers. Many aspects of our daily life benefit from CMP research: for example, plastics are used for everything from furniture to automobile bodies; composite materials are used in jet turbines and modern tennis rackets; magnetic disks are used in almost every modern information system; superconducting magnets are used in MRI tomography for medical diagnostics.
Today, condensed matter physics is one of the most active and exciting research area in both basic sciences and technological applications. At the fundamental level, CMP is intellectually stimulating due to the continuing discoveries of many new phenomena and the development of new concepts that are necessary to understand them. It is the field in which advances in theory can most directly be confronted with experiments. It has repeatedly served as a source or testing ground for new ideas (e.g., Josephson effect, integer and fractional quantum Hall effects, Aharanov-Bohm effect, mechanism of high-T_c superconductors, dissipative quantum physics, critical phenomena, mesoscopic physics, nonlinear dynamics). Another unique aspect of condensed matter physics is its intimate connection with industry. A large number of scientists trained in condensed matter physics work in industry and found the training they received in university very rewarding.

One of the main research area of KU's CMP group is superconductivity. Superconductivity, which was discovered in 1911, is a phenomenon of great intricacy, diversity, and elegance. It is one of the most interesting and challenging subfields of CMP. For instance, the mechanism of high-T_c superconductors remains unsolved despite two decades of persistent efforts by some of the leading scientists in the world. On the other hand significant progress has been made in the technical application of superconductivity. Large scale applications include the world's fastest experimental magnetically levitated train, superconducting magnets in MRI (Magnetic Resonance Image) systems, the world's largest electromagnets for thermonuclear fusion experiments, and bending and focusing magnets for the world's most powerful particle accelerators. Small-scale electronic applications include the fastest operating and the least-power consuming digital logic devices and circuits -- the Rapid Single Flux Quanta (RSFQ) logic family, the most sensitive and lowest-noise electronic and magnetic sensors (SQUIDs), the most accurate voltage standard (the Josephson voltage standard), and the highest resolution x-ray detectors, just to name a few. Superconducting devices are also studied in our group in the context of quantum computing.

The group is also very interested in physics at nanometer (0.000,000,001 meter) scales. Two of the faculty (Wu and Timm) are involved in an interdisciplinary project aiming at introducing undergraduates to nanotechnology. The department also runs a state-of-the-art nanofabrication facility that allows to create structures on this scale.

Another research area involves semiconductors and lasers. In particular, we are interested in semiconductor nano-electronics and nano-spintronics. In these research topics, we use ultrafast laser techniques to manipulate and monitor the motions of charge and spin of electrons in nanoscale devices. The control and detection can be done as fast as 100 fs (1 fs = one millionth of billionth of a second) in time, and as small as 1 nm in space. These research activities provide building blocks for the next generation electronic devices that are faster, smaller and more powerful. Furthermore, studies of nanoscale transport provide information and knowledge on quantum and coherent properties of electrons that are of fundamental importance. We are also interested in optical investigations of man-made photonic structures, including photonic crystals and left-hand materials, for potential applications in photonic technology.

The theoretical efforts in the group concern systems in which interactions between electrons are crucial for the physical understanding. Magnetic systems belong to this class. Currently, we investigate the properties of diluted magnetic semiconductors. These materials contain magnetic ions in random positions in a host semiconductor. This research is motivated by possible application in spintronics, i.e., the idea to use the electron spin in addition to its charge in electronic devices. These materials have fascinating properties. For example, the magnetic interactions depend strongly on the concentration of charge carriers. This allows to change the magnetic properties with an applied voltage, a level of control that is impossible in ferromagnetic metals. Another field of interest is the electronic transport through single molecules and through devices composed of such molecules, motivated by future molecular electronics technologies. State-of-the-art analytical and computational methods are employed to study these systems.

If you are interested in taking part in this research, please check the links for the members of the group in the left column for more information on our research projects.