PHYSICS DEPARTMENT

Nationwide, the percentage of students majoring in Physics is about 0.3%. At Williams, the physics majors comprise 4% of the class, i.e. about 10 times the national average. The average number of majors per class at Ph.D. granting institutions is 11, while at Williams, this June, we graduated a record 24 physics/astrophysics majors. While these numbers may not seem large in absolute terms (there is still plenty of opportunity for student/faculty interaction in and out of the classroom), it does mean that Williams is a nationally significant producer of future scientists. About half of our majors choose to go on to graduate programs in physics, biophysics, astrophysics, engineering, computer science, mathematics or other scientific fields (along with the odd composer or economist thrown in for good measure). In the fall of 2004, our graduates will be beginning Ph.D. programs at Harvard, Yale, Berkeley, Stanford, Santa Barbara, and Caltech, among others.

The college has identified a number of curricular areas where it wants to expand offerings. Of particular interest to the Physics department are interdisciplinary courses and tutorials. These are both areas where the department has already made a major investment of faculty time and effort, and we are hopeful that the college will be able to provide the resources to support these efforts in the long run.

In the area of interdisciplinary courses, we are currently offering 300 level courses on Protecting Information: Applications of Abstract Algebra and Quantum Physics (PHYS 316) with the Math Department and Materials Science: The Chemistry and Physics of Materials (PHYS 332) with the Chemistry Department. In fall 2003, Professor Aalberts offered a new course on Computational Biology (PHYS 315) cross-listed with the Computer Science Department. This course took an interdisciplinary approach to the problem of identifying and interpreting genomic information. In addition, Professor Stuart Crampton has recently offered a course open to both science and non-science majors on Science and Religious Experience (PHYS 342).

The Physics Department has been an early and enthusiastic supporter of tutorials. We have evolved a variation on the canonical tutorial format that works well for physics. The weekly cycle starts Thursday evening when students read a chapter in the text (sometimes along with an article from the literature). Friday there is a one-hour lecture/discussion session for the whole class. Students then spend a few days working on problem sets. Tuesday or Wednesday each pair of students meets with the professor for an hour presenting their solutions thus far and discussing any questions that have arisen. Thursday students turn in written solutions and the whole cycle begins again. While this is a demanding schedule for students (and faculty!), we find that the extra effort is well rewarded by the improvement in student’s problem solving skills. We have converted our standard upper level courses on Electromagnetic Theory, Classical Mechanics and Applications of Quantum Mechanics into tutorials. Most of our graduate school bound students take at least two such tutorials. When we interview our graduating seniors, they report that physics tutorials they have taken were among the most challenging and also the most rewarding of their educational experiences at Williams.

We are very pleased to report that, in support of our efforts to teach tutorials and interdisciplinary courses, the college approved the hire of a new tenure track faculty position in physics, and this year we welcomed Professor David Tucker-Smith to the department. His research interests lie in elementary particle physics beyond the standard model. His particular research focus broadens the expertise of the physics department in a significant way. This spring he taught a new and very successful upper level course, Gravity (PHYS 418), which introduced students to the General Theory of Relativity. The impressive enrollment (14) in this 400-level elective course reflects both the substantial interest among students in this subject, as well as the healthy number of majors we are now enjoying! We are happy to welcome Professor Tucker-Smith to Williams.

As we have noted previously, the college has received an extraordinarily generous bequest for the support of teaching and research in the Physics Department. Mrs. Frances McElfresh Perry has left the college some 12 million dollars in honor of her father, Professor William Edward McElfresh, who taught at Williams 1902-1936. Professor McElfresh was chair of the Physics Department from 1905 until his retirement. Last year, the college announced a new endowed chair associated with this gift, and we congratulate Professor Kevin Jones, the inaugural “William Edward McElfresh Professor of Physics.”

In part due to the generosity of this gift, the department has also secured substantial funds from the college to undertake a comprehensive teaching laboratory revitalization plan. New labs are being developed, and additional equipment purchased for laboratories throughout our curriculum. As always, our focus is on the pedagogical impact of the equipment as we strive to expose our students to exciting state-of-the-art experiments and techniques. The college has also committed to providing us with a set of “McElfresh” summer research fellowships for students. We hope this support, when combined with numerous existing sources of summer student support, can sustain a large and vital summer research program in the physics department for the long-term. In summer 2004, 16 Williams students will be working with faculty members in the physics department on a wide variety of experimental and theoretical research projects.

Associate Professor Daniel Aalberts taught several new interdisciplinary courses this year: Computational Biology (PHYS/CSCI 315) Sound, Light and Perception (PHYS 109) and Materials Science (CHEM/PHYS 332). He also taught Statistical Physics (PHYS 302).

Aalberts and Jeff Garland ’03 published their “finding with binding” method in Phys. Rev. E. Nathan Hodas ’04 and he developed an algorithm, which calculates the optimal binding and free energy of two RNA molecules; this BINDIGO algorithm was applied to studying RNA binding in pre-mRNA splicing reactions. They also investigated novel RNA pseudoknot structures. With Eric Daub ’04, Aalberts quantified an upper bound to the accuracy of local bioinformatics methods and developed a statistical model with superior performance.

Aalberts advised the Society of Physics Students and served on the Committee for Priorities and Resources (CPR), the Honorary Degrees Committee, and the Faculty Review Committee. He sang with the “Flatbed Jazz Band” and the faculty quartet the “Diminished Faculty. ”

Bolton spent her summer in the lab studying fast processes in nanometer scale semiconductors with research students Jennifer Simmons ’05, Zophia Edwards ’05, and Jesse Dill ’04. This work was continued by Jesse Dill in his senior thesis, and was presented at the 2004 International Quantum Electronics Conference in San Francisco. We look forward to Jenni’s return to the lab in the summer of 2004, where she will be joined by Dan Weintraub ’05. This year professor Bolton had a new opportunity to learn about local prospects for wind energy while working with thesis student Sam Arons, ’04. Bolton had a very active travel year, as she was called to act as an outside evaluator for the Physics department at Harvey Mudd College in the winter and for the Chemistry and Physics departments at Hamilton College in the spring. In addition to these special responsibilities, Bolton continued to serve as a reviewer for the National Science Foundation, Research Corporation, Physical Review, and Optics Communications. Bolton’s research is supported by a continuing grant from the National Science Foundation.

Emeritus Professor Stuart Crampton continued to teach his interdisciplinary course, Science and the Religious Experience (PHYS 342). He serves as a consultant for the Sherman Fairchild Scientific Equipment Program, and as a Director of Research Corporation, America's second oldest foundation and the first one devoted to science. He continues to be active in the Council on Undergraduate Research Physics and Astronomy Divisional Council.

Kevin Jones, the William Edward McElfresh Professor of Physics, continues to collaborate with the Laser Cooling and Trapping group at the National Institute of Standards and Technology in Gaithersburg, MD headed by Dr. William Phillips. In collaboration with NIST scientist Dr. Paul Lett, Jones uses the cold atom facilities at NIST to study collisions between atoms at <1/1000 degree above absolute zero. Atoms colliding in the presence of laser light can "photoassociate" to form molecules. Recently Jones and the NIST scientists have used this photoassociation technique to measure the highest vibrational levels in the triplet ground electronic state of the sodium (Na2) molecule. These high lying levels are unusual in that the normally small “hyperfine” structure is much larger than the “fine” structure and comparable to the “rotational” structure. The results were published in the Journal of Chemical Physics. This new data will permit construction of molecular potentials for Na2 that are of unprecedented accuracy.

Also at NIST, Jones investigated novel diffraction patterns formed when two beams of light interact in a non-linear medium (specifically rubidium vapor) with the able assistance of Aubryn Murray ’05. Aubryn’s careful measurements on the diffraction patterns formed by a single laser beam passing through the Rubidium vapor showed that the existing theory, although qualitatively correct, is not able to quantitatively explain the single beam patterns. Thus, one cannot use this theory to draw strong conclusions about the details of the two beam patterns. Jones will continue this work while on sabbatical at NIST for the 2004-2005 academic year. He has also been invited to write a major review article on photoassociation spectroscopy for Reviews of Modern Physics.

One of Jones’ earlier publications was selected for a special honor. The NIST Journal of Research, in honor of the 100th anniversary of NIST, selected 10 papers, one per decade, to be reprinted as “Treasures of the Past.” Jones’ 1996 paper, “A Spectroscopic Determination of Scattering Lengths for Sodium Atom Collisions,” was selected as representing the best of the 1990’s.

In April, Jones and Professor Tiku Majumder were the “headline act” at Williamstown Elementary School’s Third Grade Science night. Using many demonstrations, they explored the topic of “Air.”

In July 2003, Professor Tiku Majumder took over duties as department chair. During the summer of 2003, he supervised four students in the summer research program. Chris Holmes ’03, having graduated in June 2003, spent his second summer in the lab. Chris helped to introduce incoming thesis student Mark Burkhardt ’04 to the experiment and the apparatus. Chris and Mark continued work to develop a new high-sensitivity “frequency-modulation” signal detection scheme for use in studying weak atomic absorption lines. Also, rising juniors Colin Bruzewicz ’05 and John BackusMayes ’05 worked on projects associated with a new thallium experiment to study time-reversal symmetry violation in this atomic system. These included development of an optical ring cavity and demonstration of a novel laser stabilization scheme. At the end of June, Professor Majumder attended the biennial Atomic Physics Gordon Conference in New Hampshire, at which he presented a poster describing the group’s current research.

In addition to administrative duties as chair, Professor Majumder co-taught Sound, Light, and Perception (PHYS 109) in the fall along with Professor Daniel Aalberts. In the spring, Professor Majumder taught the lectures and labs for Waves and Optics (PHYS 202) to a class of 20 sophomores.

The Majumder group continues to pursue high-precision diode laser spectroscopy of thallium in their 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 (i.e. the “Weak” force) in thallium in terms of fundamental physics. The group bade farewell to Dr. Michael Green, who completed one year as a postdoc, and now has returned to his native Australia. We wish Michael the best of luck! In January, the Majumder group welcomed new postdoc Dr. Ralph Uhl to Williams. Dr. Uhl completed his Ph.D in Germany and had worked in industry for several years. He has quickly come up to speed on the experiments in the Majumder lab and worked closely with thesis student Mark Burkhardt ‘04 during the academic year. Mark’s thesis work was hindered by the untimely demise of two different diode lasers. Nevertheless, he was able to resurrect our frequency-doubled UV laser system, and work out the details for a new, two-step excitation scheme to do further thallium spectroscopy. Professor Majumder gave seminars at Amherst College and at Williams last fall on the current work of the group. Mark Burkhardt ’04, and Dr. Uhl joined him at this year’s DAMOP annual conference in Tucson, AZ in late May, where two posters on current research in the group were presented and well-received. Mark will be continuing work in the lab during the summer 2004, prior to beginning a Ph.D. in physics at Stanford University this fall. We look forward to having incoming thesis students Colin Bruzewicz ’05, and Joe Kerckhoff ’05 (both veterans of the Majumder lab!) join Mark, Dr. Uhl, and Professor Majumder in the lab this summer.

Assistant Professor David Tucker-Smith arrived from his postdoctoral appointment at MIT at the end of the summer of 2003. In the fall semester, he taught Particles and Waves – Enriched (PHYS 141), and in the spring semester, he taught a new course on Einstein’s theory of general relativity, Gravity (PHYS 418). On the research side, Tucker-Smith continued his study of extensions of the standard model of particle physics, focusing on extended Higgs sectors and on warped spacetimes. In the spring, he was awarded a $31,000 grant from the Research Corporation in support of this research. This summer Tucker-Smith will be working with thesis students John Backus-Mayes ’05 and Sean O’Brien ’05 to study supersymmetric models of leptogenesis (a mechanism for generating matter-antimatter asymmetry in the early universe).

Professor Jefferson Strait and his students have built and are studying an optical fiber laser that produces pulses of light about one picosecond long. Unlike most lasers, which 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. 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 2003, Paul Crittenden ’04 and Matt Spencer ’05 worked with Strait. They made substantial progress with the fiber laser, stabilizing its output so that the laser now can produce pulses for hours at a time. This stability enabled them to measure the autocorrelation and the spectra of the pulses for the first time. Paul went on to write his senior honors thesis with Strait. Now that he has graduated, Paul works for Coherent Radiation developing fiber lasers.

Much work remains to be done with Strait’s fiber laser. Aubryn Murray ’05 and Joe Shoer ’06 are joining Strait during the summer of 2004. They will work on understanding how the polarization of light influences the operation of the fiber laser. The eventual goal is to use the laser to study how short pulses propagate in optical fiber.

Strait served as pre-engineering advisor during the fall term and continues to serve as department web master.

Dwight Whitaker taught Introductory Quantum Mechanics (PHYS 301) in the fall term for the third year. In the spring, he taught Foundations of Modern Physics (PHYS 142) for the first time.

During the summer of 2003, Whitaker worked with Sarah Iams ’04, Justin Brown ’05 and thesis student Leon Webster ’04 on improving our Magneto-Optical Trap (MOT) of rubidium-87 atoms. Our new MOT can hold approximately 1 billion rubidium atoms at a temperature of a few hundred microKelvin. Whitaker also worked with Zach Kung ’04 on upgrading some of the labs for Introductory Quantum Mechanics (PHYS 301). Zach helped to develop JAVA applets, which numerically solve the Schrödinger equation, and a new laboratory experiment where students use diode lasers to observe fine spectral details in rubidium atoms.

During the academic year, Leon Webster ’04 and Whitaker worked towards transferring cold atoms from the MOT into a dipole trap where they can be further cooled to form a Bose-Einstein Condensate (BEC)—a new form of matter where quantum mechanical nature of the atoms becomes apparent. At extremely low temperatures, these clouds of atoms will begin to behave like one “super-atom” rather than as a collection of individual particles. Both Whitaker and Webster presented their work at the annual meeting of APS’s DAMOP in Tucson, Arizona in May.

This summer Whitaker’s lab will continue towards making a BEC with the help of Utsav KC ’06 and thesis student Justin Brown ’05. In addition, Whitaker has also entered a collaboration with Professor Joan Edwards in the Biology department to study the dynamics of a flower, which explosively pollinates. This summer they will take more high speed images of this process, and Whitaker will present some of the results in a Summer Science Colloquium entitled “Cornus Canadensis: Nature’s Weapon of Mass Reproduction”.

In the summer of 2003, Professor William Wootters participated in a workshop at the Kavli Institute for Theoretical Physics in Santa Barbara, which brought together theoretical physicists from undergraduate institutions around the country to share ideas and to compare their experiences doing research with undergraduates. (He returned with even greater appreciation for the supportive research environment that one finds at Williams.) He spent most of the rest of the summer actually doing research with three students: John Mugno ’05, Josh Cooperman ’05, and Matt Hoffman ’04. All three did theoretical projects in quantum physics. John’s work was in quantum cryptography, Josh’s was on the “subadditivity” of quantum entropy, and Matt’s was on an alternative representation of quantum states known as the Wigner function.

Matt continued his research with Professor Wootters during the academic year in the form of a senior thesis project, building on the work of Professor Wootters’ former student Kate Gibbons ’03. One of the new features in Matt’s thesis was an illustration of how one might use the Wigner function to picture the steps of a quantum computation. Gibbons, Hoffman and Wootters have now written a paper on their work and submitted it for publication. In the summer of 2004, Professor Wootters will be working with Josh Cooperman again, on a new project, and with Ersen Bilgin ’06.

In fall 2003, Professor Wootters taught, for the second time, our recently introduced Seminar in Modern Physics (PHYS 151) for advance-placed first-year students, this time with additional laboratory experiments and an optional conference section. Each student gave a talk on a topic in modern physics and wrote a paper based on Feynman’s book, The Character of Physical Law. In the spring, Professor Wootters taught Mathematical Methods for Scientists (PHYS/MATH 210) and The Physics of Everyday Life (PHYS 100), but he did not walk on hot coals as Professor Whitaker did when he taught PHYS 100.

Bryce Babcock, Staff Physicist and Coordinator of Science Facilities, continued his collaborations with Professor Jay Pasachoff and Dr. Steven Souza. Pasachoff and Babcock took a team of students to Thessaloniki, Greece in June 2004 to observe the June 8 transit of Venus. Further details regarding this effort may be found in the Astronomy Department section, as well as information on their planetary occultation work with James Elliot’s group at MIT that resulted in the award of a joint NASA equipment grant to Williams and MIT for future occultation work. In addition to his efforts developing research and instructional laboratory apparatus for the sciences, Babcock serves on the Animal Care, Safety, WilliamsScene and Science Executive Committees. He continues to edit the Report of Science at Williams, the annual review of science activities at Williams, which is published in both print and web accessible versions (see http://www.williams.edu/go/sciencecenter/center/.)