Kenneth G. Libbrecht --Home
--Professor of Physics at Caltech
--and Chairman of the Physics Department
|Current Research Interests|
|Advanced detector development for the Laser Interferometer Gravitational-wave Observatory (LIGO). The LIGO project is aimed at detecting and studying gravitational-wave signals from violent astrophysical events, such as supernovae or coalescing neutron stars and black holes. For more information on all aspects of the LIGO project, see the LIGO web site. My work in LIGO is currently focused in two areas. The first is an instrument called the Thermal Noise Interferometer (TNI), which is a test-bed suspended interferometer at Caltech. We are using this instrument to examine fundamental and technical sources of noise that limit the sensitivity of LIGO. Our second undertaking is a photothermal interferometer for measuring the properties of optical coatings used in the LIGO detectors.|
|The Physics of Crystal Growth and Pattern Formation in Ice. This project is essentially a case study of the growth of ice crystals from the vapor phase, the purpose of which is to better understanding pattern formation in nonlinear nonequilibrim systems. The diverse morphologies seen in snow crystals are largely due to the bizarre temperature dependence of ice crystal growth rates, a phenomenon that was discovered 75 years ago and remains unexplained to this day. We have been making precise measurements of the growth rates of the different facets of ice crystals under controlled conditions to gain insights into the temperature dependent molecular structure of the ice surface and how it affects crystal growth. Pictures (and movies) of growing snow crystals can be found at my Snow Crystals page.|
|Electrically Modified Crystal Growth and Structure Formation. When a high voltage is applied to a growing crystal, a number of electrophysical and electrochemical effects can conspire to produce novel growth behaviors, in particular the growth of nanoscale needle-like structures. We are investigating the electrically modified growth and morphology of a variety of materials in order to better understand the mechanisms of needle formation, as well as to explore possible applications.|
|Tunable Diode Lasers in Physics Education. Grating-stabilized tunable diode lasers can provide an inexpensive and versatile source of laser light for doing simple experiments in atomic, molecular, and optical physics. We have developed several such experiments for the undergraduate laboratory, which can be seen at the Ph76 website. We have also been working with TeachSpin to produce a commercial tunable diode laser system aimed at the undergraduate education market, which should be available sometime in early 2004.|
|Some Past Lives|
|Helieseismology and the Large-Scale Structure of the Sun. Convective motions near the solar surface generate acoustic waves that resonate inside the Sun, resulting in global oscillation modes with periods around five minutes. We made extensive measurements of these global modes in the late 1980s at Big Bear Solar Observatory, recording Doppler images of the entire solar disk each minute for many months on end. Analysis of these tens of thousands of images (back when a GByte of disk space was something special!) allowed us to measure the solar mode frequencies to unprecedented accuracy. By examining the mode frequencies and amplitudes, as well as the frequency splittings of mode multiplets, information about the interior structure and dynamics of the Sun could be extracted, including a measure of the interior rotation rate of the Sun.|
|Laser Cooling and Trapping of Individual Atoms. We built laser-cooled magneto-optical atom traps in the early 1990s that could capture and observe individual cesium atoms. This technology was used to investigate the dynamics of atom trapping in the low-atom-number limit. We also investigated the use of microfabricated planar current structures for making microscopic magnetic atom traps.|
Courses and Education
Ph77 -- Advanced Physics Laboratory. Click here for course information, including downloadable descriptions of the individual labs.
CV and Publications
Here are links to a curriculum vitae and a list of publications.