PHYSICS DEPARTMENT

The Physics Department had a very productive year. While enrollments in our introductory physics course for premedical students have dropped, the enrollments in our introductory course for potential physics majors and in our courses for non-science majors are booming. Sixteen juniors and seniors enrolled as physics majors and we shared six astrophysics majors with the Astronomy Department, giving us a very lively and talented group of students in our upper-level courses. Graduating seniors report to us that the physics faculty members are unusually accessible and that the department has a strong sense of community.

Student-faculty research continues to be an essential part of our program. Under the leadership of Professor Bill Wootters, our department serves as a National Science Foundation Research Experiences for Undergraduates (REU) site. This program and other grants allow us to hire several students to work with us full time on our research in the summer. During summer 1998, six Williams students and five students from other colleges joined our faculty to work on experimental and theoretical projects. Two of those students continued their research during the academic year, completing honors theses. This coming summer (1999) we will have nine students from Williams and two from other colleges. The students meet regularly for tea and cookies, as well as for more formal talks given by faculty or students. Those students doing experimental projects take a short course on machine shop work and another on electronics.

Ricky Joshi ‘01 and Camille Burnett ‘01 adjust the autocorrelator in Prof. Bolton’s research lab.

During the academic year, Eric Kramer joined the department as a visiting assistant professor. Professor Kramer had earned his Ph.D. from University of Chicago in 1996 and came to us from a postdoctoral research fellowship at Brandeis University. This coming fall, he will begin a new position as an assistant professor of physics at Simon’s Rock College, in nearby Great Barrington, MA.

Assistant Professor Daniel Aalberts presented two new courses: a tutorial Classical Mechanics and Fluid Mechanics and a Winter Study course Science of Sports co-taught with Steve Swoap of the Biology Department, which included ten new hands-on experiments. He and Lee Park of the Chemistry Department designed a new course, Chemistry and Physics of Materials. He advises the Society of Physics Students.

With summer research students Brian Gerke ‘99, Qiang Sun ‘00, Jonathan Pyle ‘99 (Swarthmore), and Lucas du Croo de Jongh (Leiden Ph.D. ‘00), Aalberts studied ultrafast dynamics of photoactive molecules. In November, Aalberts and Gerke visited collaborators at Leiden University to begin preparation of a journal article. In the spring, Ian Eisenman ‘99 joined the group, studying structural properties of double-bonded molecules. Gerke and Pyle both wrote honors theses based on their collaborations.

Aalberts participated in the Princeton Lectures on Biophysics, hosted by the NEC Research Institute. He was one of 1% of 11,000 participants at the American Physical Society’s Centennial Meeting asked to contribute a lay language version of their work. His research also was highlighted in the Williams Record. (See <http://positron.aps.org/meet/CENT99/vpr/layfc19-05.html>.and <http://record.williams.edu/articles/11054.html>.)

Aalberts gave an on campus presentation for the Bronfman Summer Research program entitled “Ultrafast Dynamics of Rhodopsin, the Molecule that Makes Us See.” He also gave an on campus presentation for the Physics Summer Research program entitled “Sequencing DNA in a New Way: the Old Ball and Chain.”

Assistant Professor Sarah Bolton was on sabbatical leave during the 1998-1999 year. She spent the year at Lawrence Berkeley National Laboratory in Berkeley, CA studying ultrafast dynamics in semiconductors. In this work, a laser producing very short pulses of light (less than 5 times 10^–14 seconds = 50 femtoseconds in duration) is used to explore the motions of electrons in semiconductors. The laser pulse acts much like a strobe light, allowing observation of electronic processes which take place on the femtosecond time scale. The processes which can be explored with this technique include interactions among electrons, as well as interactions of electrons with thermal vibrations. Bolton’s work this year focused on dynamics in the compound ZnSe, which has particularly strong electron-electron interactions, leading to well-defined new resonances. Bolton returns to Williams for the summer program in July 1999, to continue this research with students Mark Acton ‘00, Camille Burnett ‘01, and Ricky Joshi ‘01.

In August of 1998, Bolton was awarded a National Science Foundation grant of $79,000, to be used for equipment and student summer stipends in the continuation of research at Williams on the behavior of ultrafast lasers. This project was started with Sarah Dugan ‘97, Rob Jenks ‘98, and Chris Elkinton ‘98, and will be continued by Mark Acton ‘00.

Professor Stuart Crampton completed his fourth and last year as the college’s Provost. He also completed his terms on the National Academy of Sciences Board of Assessment of the Physics Programs at the National Institute of Standards and Technology and on the National Research Council’s Committee on Atomic, Molecular, and Optical Sciences. He continues to serve on the Board of Directors of Research Corporation and as a consultant to the Sherman Fairchild Foundation Scientific Equipment Program. Next fall he will be on leave as a Visiting Scholar at the Center for Theology and the Natural Sciences in Berkeley, CA.

Professor Kevin Jones was on sabbatical at the National Institute of Standards and Technology in Gaithersburg, MD. He has a long-standing research collaboration with a group there headed by William Phillips. When Phillips was awarded the 1997 Nobel Prize in Physics he invited Jones to come to Gaithersburg for an extended two-year sabbatical. This research group has developed techniques for slowing atoms to near absolute zero. Jones, working with Paul Lett and others, has been “photoassociating” these cold (< 0.001 degrees Kelvin) sodium atoms to produce Na₂ molecules. With assistance of Ginel Hill ‘00 he has explored some molecular states in which both of the two chemically active electrons are excited to higher orbitals. Molecules in these states vibrate perhaps 20 times (on average) and then eject an electron. He has also been looking directly at the dynamics of the ionization process using a short pulse laser to produce excited atoms which then collide to produce molecular ions.

In March, Jones attended the international workshop “Cold Atomic Collisions: Formation of Cold Molecules,” at the Centre de Physique des Houches, Les Houches, France. A paper written with co-authors from China and Canada was recently accepted for publication. Jones is in the process of writing two others, one with co-authors in France and the other with a group in Holland. More locally, he has just written a paper on the theory of photoassociation lineshapes with a theoretical chemistry group one floor up at NIST.

Despite being away from Williamstown, Jones notes that he has still had numerous Williams Physics connections. In addition to having Ginel Hill ‘00 back at NIST for another summer of research, Jones shares an office with Chad Orzel ‘93 who has just completed a Ph.D. through a NIST/University of Maryland program (run by Michael Coplan ‘60). Gordon Jones ‘89 is a post doc at NIST. At a recent laser conference in Baltimore, Jones saw Tom Gallagher ‘66, Dan Kleppner ‘53, Guy Beadie ‘90, James Heyman ‘85, Dave Citrin ‘85, and Matt DeCamp ‘96 as well as Prof. Sarah Bolton.

Visiting Assistant Professor Eric Kramer published two papers in which he applied the theory of liquid crystals to the behavior of biological macromolecules in solution. He also continued work on the topological classification of patterns in wood grain. The goal of the classification is to illuminate the developmental mechanisms at work as the tree grows new wood.

During the 1998-99 year, Assistant Professor Tiku Majumder taught Physics 301, Introductory Quantum Mechanics, Physics 010 Light and Holography (during Winter Study), and Physics 109, Sound, Light, and Perception. Physics 109 is a course developed recently by Profs. Majumder and Bolton to offer a hands-on, interactive physics course for non-majors. During the summer of 1998, Majumder supervised four students in the summer research program. Leo Tsai ‘98 stayed on for the summer after his senior year to complete his thesis research project (results to appear in the journal, Physical Review A in July 1999). Also during the summer, Rob Lyman ‘99 began his thesis work, while Alex Jarvis ‘99 and J.J. Ackles (Vassar) ‘99 spent their summer completing a number of laboratory projects. During the academic year, Prof. Majumder again organized the department colloquium series.

With the aid of funds from a new NSF/RUI grant, Dr. David S. Richardson joined the Majumder research group and the department in December as a postdoctoral research associate. Dr. Richardson recently received his D. Phil. in experimental physics from the University of Birmingham, UK, and will be working closely with Prof. Majumder and his research students on all aspects of the experiments. The Majumder group continues to pursue thallium laser spectroscopy experiments in his atomic physics lab. A better understanding of the structure of this complex atom is essential to be able to interpret recent precise measurements of parity nonconservation in thallium in terms of fundamental physics. Rob Lyman ‘99 completed a successful thesis project in which he completed construction of a new atomic beam apparatus (worked on previously by Julie Rapoport ‘97 and Peter Nicholas ‘98). Rob also helped to bring on-line a new frequency-doubled diode laser system, and used the UV light to obtain our first spectroscopic data of the thallium 6P1/2 –7S 1/2 transition at 378 nm.

In October, Professor Majumder gave a pair of general-audience lectures on his research for the Williams College Sigma Xi Lecture Series titled “Tests of Fundamental Symmetries and Searches for New Physics: I. Recent History and II. Current Atomic Experiments.”

In March, Majumder, Lyman, and Richardson (along with 11,000 other physicists!) attended the exciting Centennial Meeting of the American Physical Society in Atlanta, GA, at which they presented two posters on current experimental work.

Associate Professor Jefferson Strait served as chair of the department this year. In addition to the routine duties of a chair, he spent a good deal of time planning for the Physics Department’s part of the science facility renovation and expansion project. While the department will not occupy space in the new building, we are excited about converting the present Physics and Astronomy library space into an introductory teaching laboratory named after Professor David Park. We also look forward to a 2,800 square foot laser research laboratory that will be constructed in the Bronfman Science Center.

Strait and his students have built an optical fiber laser designed to produce pulses of light about 10^-12 seconds long. Unlike most lasers that use mirrors to confine light to the laser cavity, an optical fiber laser uses a loop of fiber as its cavity. A section of fiber doped with erbium serves as the gain medium. Strait and his students pump the gain medium with 1.06 μm light and it lases at 1.55 μm, conveniently the same wavelength at which optical fiber is most transparent and therefore most suitable for telecommunications. During the summer of 1998, Allegra Martin ‘99 and Meredith Dill (Brown University ‘00) improved stability of the laser and prepared to measure its pulse duration. Clay Stein ‘00 and Adam Halverson (Reed College ‘00) will continue this work during the summer of 1999. The eventual goal is to study how these short pulses propagate in optical fiber.

Professor William Wootters continued his theoretical research on quantum entanglement (a peculiarly quantum mechanical kind of correlation between two objects), collaborating not only with students but also with researchers at IBM’s Watson Research Center. In the summer of 1998, he worked with two students from other institutions, Nurit Baytch of Harvard and Alex Wong of Carleton, who were supported by the department’s Research Experiences for Undergraduates grant. Together they made progress towards generalizing a formula derived earlier by Prof. Wootters and Scott Hill ‘97, which expresses the amount of entanglement contained in a state of two simple quantum particles such as electrons.

Prof. Wootters developed and taught three new courses during the 1998-1999 academic year. How Things Work is a technologically oriented course for a general audience. Mathematical Methods for Scientists is an up-to-date version of a course the department had taught many years ago and revived this year. The final one, a new interdisciplinary Winter Study course entitled Building and Cracking Codes: How Will We Protect Information in the Coming Centuries?, was taught with Prof. Susan Loepp of the math department.

Staff Physicist and Science Facilities Coordinator Bryce Babcock collaborated in observations of the total solar eclipse in Ramnicu Valcea, Romania with Prof. Jay Pasachoff. (For further details regarding this work, see the astronomy departmental section.) They are co-authors on an article to be published in Icarus on observations of increasing pressure in Triton’s Atmosphere, with James Elliot of MIT as first author. In addition to his work developing research and instructional laboratory apparatus for the sciences, he taught PHYS 456, Advanced Electronics, in the spring semester. He was also kept busy with construction activities in the new science facilities as well as editing the Report of Science. He oversees the Science Web Site, http://www.williams.edu/BSC. This site provides information about the sciences at Williams, including html versions of recent copies of the Report of Science at Williams, a calendar of science activities, and information on the Science Building Project.

Class of 1960 Scholars in Physics

PHYSICS COLLOQUIA

OFF-CAMPUS PHYSICS PRESENTATIONS

“Dynamics of Associative Ionization of MilliKelvin Sodium Atoms”, “Ultracold Photoassociation Spectroscopy of Sodium Molecules,” and “Two-color Photoassociative Autoionization of Ultracold Sodium.” with various co-authors
Workshop on Cold Atomic Collisions: Formation of Cold Molecules
Centre de Physique des Houches, Les Houches, France March 1-5, 1999

“Precise Measurements of Thallium Atomic Structure and Tests of Fundamental Symmetries”
National Institute of Standards and Technology – January 20, 1999
“Precise Laser Spectroscopy of Thallium: Measuring Atomic Structure and Testing Fundamental Physics”
Colgate University – February 2, 1999
“Precise Atomic Structure Measurements and Fundamental Symmetry Tests within the Thallium 6P1/2 – 6P3/2 1283 nm Transition”
16^th International Conference on Atomic Physics – Windsor, Canada – August 1-5, 1998 – with L.L. Tsai ‘98, and P.C. Nicholas ‘98, contributed poster
“Atomic Structure Measurements in Thallium using a 378 nm Frequency-Doubled Diode Laser”
1999 APS Centennial Meeting – Atlanta, GA – March 20-26, 1999 – with R.N. Lyman ‘99 and D.S. Richardson, contributed poster
“Proposed Test of Long Range T-Violating Forces in Atomic Thallium”
1999 APS Centennial Meeting – Atlanta, GA – March 20-26, 1999, contributed poster

“Quantifying Entanglement”
Fourth International Quantum Communication, Measurement, and Computing Conference, Northwestern University
“Quantum Theory: Still Crazy After All These Years”
Aurora University
“Quantum Entanglement as a Resource for Communication”
Dartmouth College

PHYSICS DEPARTMENT

Class of 1960 Scholars in Physics

PHYSICS COLLOQUIA

OFF-CAMPUS PHYSICS PRESENTATIONS

POSTGRADUATE PLANS OF DEPARTMENT MAJORS