PHYSICS DEPARTMENT

The fall Convocation ceremonies celebrated the completion of the new Science Center. A group of distinguished scientists was invited to receive honorary degrees. In addition to the usual ceremonies, each of the honorees presented a lecture describing his or her research. These lectures gave a fine sense of the breadth and vitality of the scientific enterprise as Williams dedicated this marvelous new facility. Two honorees were of particular interest to the Physics Department. The first, Prof. Daniel Kleppner ’53 of MIT, is one of the leading figures in the atomic Physics community. His provocatively titled talk “The First Two Hundred Years of Quantum Mechanics” stimulated a lively discussion and provided a fitting capstone to the lecture series. In addition to participating in the official activities, Prof. Kleppner was kind enough to present lectures to two physics classes and to meet informally with students. The second honoree of particular interest to the department was Prof. Jocelyn Bell Burnell of the Open University (UK). She gave a lively and engaging talk describing the twists and turns along the path that led to her discovery of pulsars.

The renovation of the Thompson Physical Laboratory, the final step in the creation of the Science Center, was completed a few months after the official opening. The move back into the nicely renovated spaces went surprisingly smooth. Although there were some close calls, we were able to offer our popular lab-based Winter Studies in Holography and Electronics even as workers completed the last installation of electric outlets, etc. The second floor space formerly housing the library has been transformed into the spacious David Park Laboratory. This room and the corresponding lab on the third floor provide us with greatly improved space for introductory teaching labs. On the first floor, we were able to clear out some old partitions and create a very nice student common room. Outfitted with library-style furniture, this room provides an inviting space for students to gather to study quietly or discuss physics problems at the blackboard. Our twice-weekly student/faculty “teas” are held here. We are very pleased that the informal student-student and student-faculty interaction so central to our program has been encouraged and supported by the new space.

While building matters occupied much of our attention for the year, we also carried out the important task of searching for a new tenure track assistant professor. Although the overall number of applicants was down from a few years ago (a healthy sign for the profession), we continue to attract strong candidates looking for the particular balance of teaching and research that Williams offers. Joining us July 1 will be Dr. Dwight Whitaker currently a post-doc at the University of Colorado. He is presently working on atomic physics techniques for producing Bose-Einstein condensates of dilute atomic gasses. His thesis work was in more conventional low temperature experiments so he brings a wide range of interest and skills to the department.

Assistant Professor Daniel Aalberts was on sabbatical leave the 2000-2001 academic year. In the fall, he was a visitor at the Center for Studies in Physics and Biology at Rockefeller University where he collaborated with Eric Siggia on RNA folding and modelling gene chip kinetics. That work continued through the spring and will involve summer students Kristina Weyer ’03 and Mike Baiocchi ’03.

Aalberts also actively supervised student research projects on campus. Thesis student Ben Cooper ’01 studied how the optical properties of polyenes (molecules with multiple double bonds) respond to being mechanically stretched. Fritz Stabenau ’02 investigated structural transitions of polyenes. John Parman ’02 simulated lipid bilayer dynamics, and Rachel Horwitz ’03 studied the shapes of folded proteins.

With the “Diminished Faculty”, a quartet of science faculty, Aalberts performed to alumni groups and classes.

In 2000-2001, Assistant Professor Sarah Bolton taught PHYS 301, Introduction to Quantum Mechanics in the fall. In the spring, she taught PHYS 142, Physics Today, as well as PHYS 451, Solid State Physics. With Lee Park of the Chemistry department, Bolton organized the “Bernhard Science Symposium” which brought ten prominent women scientists to campus to present their work on January 24-25, 2001.

During 2000-2001, Bolton worked with Ricky Joshi ’01 in studies of semiconductors using an ultrafast Titanium Sapphire laser. The laser produces pulses of less than 20 femtoseconds in duration (20 x 10-15 seconds) - short enough to take “snapshots” of electron motions and molecular vibrations. They are using the laser to determine how these very fast motions are altered when the electrons in a material are confined to two dimensions. Work on this project will continue in the summer of 2001 with students Mark Burkhardt ’04 and Alex Glenday ’02.

The department is pleased to note that Prof. Bolton successfully passed through the tenure process this fall and will be promoted to associate professor as of July 1, 2001.

Professor Stuart Crampton continued his research into the implications for religion of modern science and designed a course on that subject to be taught in the spring of 2001. He continues to serve on the Board of Directors of Research Corporation and as a consultant to the Sherman Fairchild Foundation Scientific Equipment Program and the Academic Excellence study of the role of research in the natural sciences at undergraduate institutions.

Department Chair and Professor of Physics Kevin Jones returned from a two year sabbatical at the National Institute of Standards and Technology in Gaithersburg, MD. Jones has a long-standing research collaboration with the Laser Cooling and Trapping Group there headed by Dr. William Phillips. This group pioneered techniques for using lasers to produce samples of very cold atoms (<1/1000 degree above absolute zero). Among the many interesting scientific opportunities opened by the development of these cooling techniques is the ability to produce translationally cold molecules by photoassociating two atoms. Working with Dr. Paul Lett and other NIST staff, Jones and his students have used this photoassociation process to study molecules in states difficult to assess by other means. From the details of the molecular spectra one learns not only new information about the molecules, but also about the properties of the constituent atoms and the nature of the collisions between atoms at these very low temperatures.

Recently Jones and colleagues showed that application of light tuned near a photoassociation resonance can dramatically alter the collision properties of atoms through the formation of a so-called “optical Feshbach resonance.” This process had been discussed theoretically but had not previously been observed. One of the “hottest” areas in atomic physics is the study of Bose-Einstein condensates: gasses of atoms cooled so low that they all fall into the lowest possible quantum state. The collisional properties of the atoms play a central role in understanding the properties of the condensate. Much of Jones’s recent work has been directed towards making accurate measurements of these collisional properties. There is speculation that optical Feshbach resonances recently observed by Jones will be useful in manipulating the properties of condensates. Jones also participated in an experiment to measure the rate of photoassociation in condensate. In agreement with theory, the rate can be surprisingly high despite the very low velocity of the atoms.

In the fall, Jones traveled to Graz, Austria to describe some of this work at the Workshop on Prospects of Cold Molecules II. At the annual meeting of the American Physical Society Division of Atomic Molecular and Optical Physics, held this year in London, Ontario, Jones presented some new results on the formation of cold molecules. Along with Sarah Iams ’04 he will be returning to NIST this summer to continue this work.

During the summer of 2000, Assistant Professor Protik Majumder supervised three students in the summer research program. Andrew Speck ’00 stayed on for the summer to continue his thesis work before leaving to begin a Ph.D. program in Physics at Harvard. Andrew was joined by incoming thesis student, Paul Friedberg ’01, and rising junior Charlie Doret ’02. These students worked closely with current postdoctoral associate Dr. David Richardson on the current atomic thallium spectroscopy experiments. During the month of June (2000), the group moved the Majumder lab into the new Laser Facility in the basement of Bronfman, and then presented a poster at the 2000 meeting of the Division of Atomic Molecular and Optical Physics (DAMOP) of the American Physical Society in Storrs, CT.

During the 2000-01 academic year, Majumder taught PHYS 141, Particles and Waves - Enriched, the tutorial, PHYS 402T, Topics in Quantum Mechanics, and PHYS 400, Thermal and Statistical Physics. He and Prof. Bolton jointly taught an Electronics course during WSP, the first departmental course offering in the brand new David A. Park teaching lab. Prof. Majumder also served as the liaison to the Society of Physics Students group.

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 in thallium in terms of fundamental physics. Paul Friedberg ’01 completed a thesis this year entitled “Measuring the Stark Shift in the 6P_1/2-7S_1/2 378nm Transition in Atomic Thallium”. Building on the work of previous thesis students, Paul was able to obtain our first atomic beam thallium spectra. This involved substantial work in frequency-stabilization, frequency-doubling, and tuning of the laser system. Equally important, it involved final development and testing of the atomic thallium beam apparatus and the vacuum system. As expected, the beam spectra show an order-of-magnitude improvement in resolution compared to the UV spectra obtained in the vapor cell. (The latter was described in a July 2000 Phys. Rev. A article by Richardson, Lyman ’99, and Majumder). Paul also obtained and analyzed the first data to measure the Stark shift by the method developed in our group, involving simultaneous application of a very large, well-known electric field, and an acousto-optic-modulator driven laser frequency shift. The department has nominated Paul for the national Apker Award, given annually by the American Physical Society for the best undergraduate thesis research project. Postdoc David Richardson worked with Paul on various aspects of this project, and pursued work on our other NIST-funded time-reversal violation experiment. In this latter experiment, a high-finesse optical ring cavity is being designed for use with an infrared 1283 nm diode laser, which will eventually be incorporated into the atomic beam apparatus.

In June 2001, Charlie Doret ’02 officially began his thesis work, and, joined by rising sophomore Elliot Morrison ’04, will continue both the Stark shift work and the NIST experiment development work. Finally, with some regret, and best wishes for the future, we bid farewell to postdoc David Richardson who will be taking a teaching job in Oklahoma City, OK beginning in July 2001. We thank David for his valuable contributions to the work, for his effective supervision of many undergraduates, and for his generous and friendly presence in the lab.

Emeritus Professor David Park, encouraged by the success of The Fire within the Eye, has begun to think about a new book, to be known as The Grand Contraption. What it will be about is anybody’s guess.

Associate Professor Jefferson Strait taught PHYS 100, The Physics of Everyday Life, in the fall term and was on sabbatical leave in the spring term. He served as a member of the Executive Board of the New England Section of the American Physical Society, attending section meetings at Central Connecticut State University and at Middlebury. He also attended the Conference on Lasers and Electro-Optics held in Baltimore in April.

Strait and his students have built an optical fiber laser designed to produce pulses of light about 10-12 seconds 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. Strait and his students pump the gain medium with 1.06 µm, conveniently the same wavelength at which optical fiber is most transparent and therefore most suitable for telecommunications. During the summer of 2001, John Spivack ’02 has joined Strait to continue that work. The eventual goal is to study how these short pulses propagate in optical fiber.

Professor William Wootters supervised two thesis students this year, Ken Dennison and Duane Lee. Both made new contributions to our understanding of quantum entanglement, a phenomenon that underlies much of the recently proposed technology known as quantum information processing. Ken’s work, which explores the physical limits on multiparticle entanglement, has already been presented off campus at a conference on quantum information held at Rochester University. Wootters also supervised two sophomores, Kate Gibbons and Sarah Nichols, in independent projects over the winter study period. Kate studied the interpretation of quantum mechanics while Sarah did research on alternative definitions of entropy.

In addition to teaching the standard courses PHYS 131, Particles and Waves, and PHYS 210, Mathematical Methods for Scientists, Wootters co-taught with Prof. Susan Loepp of the Mathematics Department a new course, MATH/PHYS 316, Protecting Information: Applications of Abstract Algebra and Quantum Physics. Development of the course, which includes topics of current research such as quantum cryptography and quantum computation, was supported by a grant from the National Science Foundation. In the coming months, Loepp and Wootters will be polishing their lecture notes and other course materials for use at other institutions, particularly Vassar College and Denison University where faculty members are already planning to teach the course. The course materials are all currently available at http://www.williams.edu/williams-only/crypto/.

Staff Physicist and Coordinator of Science Facilities, Bryce Babcock, collaborated with Professor Jay Pasachoff on observations of the total solar eclipse in Lusaka, Zambia in June 2001. (For further details regarding these experiments and other publications, see the Astronomy departmental and faculty publications sections.) In addition to his work preparing for the eclipse and developing other research and instructional laboratory apparatus for the sciences, he continues to edit the annual Report of Science at Williams. With the conclusion of the Science Building Project in the fall, his work on the Science Building Committee has come to an end - even though portions of this project seem to continue indefinitely. However, he has had no lack of involvement with construction, since he has been building committee chair and “clerk of the works” for the building program at Williamstown Community Bible Church during the past year. This project is nearly complete, with the new building having opened for use June 17, 2001.

Visiting Assistant Professor Paul Weber, formerly at Grinnell College, joined us for the year. Weber ably taught an electricity and magnetism course for sophomores and the second half of the premedical physics course. We wish him well in his future endeavors.

[Colloquia are held jointly with Astronomy. See Astronomy section for additional listings.]

Professor Timothy Halpin-Healy
Barnard College

“Extremal Paths in a Random Energy Landscape”
Professor Priyan Dias
University of Moratuwa, Moratuwa, Sri Lanka

“Constructing a Philosophy of Engineering”
Dr. Alexander D. Cronin
M.I.T. - Cambridge, MA

“Atom-Beam Interferometry and the Transition from Quantum to Classical Behavior”

Class of 1960’s Scholars program
Professor David S. Citrin ’85
Washington State University

“How Fast Can Semiconductors Emit Light? Exciton Polaritons in Low-Dimensional Systems”
Class of 1960’s Scholars Program
Professor Frank Moscatelli
Swarthmore College

“NIST F2 - The Cesium Fountain Atomic Clock”

Class of 1960’s Scholars Program
Professor William Wootters
Williams College - Physics Department/Computer Science Department

“Computing in Parallel Worlds: The Quantum Search Algorithm”
Professor John Krupczak
Hope College - Holland, MI

“Demystifying Technology: Using Consumer Products to Explain Some Principles of Physics”

Class of 1960’s Scholars Program
Dr. Michael I. Larkin
Columbia University

“Unconventional Superconductors: How Many Ways Can Electrons Avoid the Pauli Exclusion Principle?”
Dr. Philip Collins
IBM - T.J. Watson Research Center

“Carbon Nanotube Electronic Devices”
Dr. Janice Hudgings
Mount Holyoke College

“Vertical-Cavity Surface Emitting Lasers: A Bright Idea”
Dr. Dwight Whitaker
University of Colorado - JILA

“The People’s BEC: Towards a Bose-Einstein Condensate for the Masses”
Dr. David DiVincenzo
IBM Watson Research Center

“Prospects for the Physical Implementation of Quantum Computation”

Class of 1960’s Scholars Program
Professor Jay Lawrence
Dartmouth College

“Nonexponential Decay and Quantum Measurement Paradoxes”
Class of 1960’s Scholars Program
Dr. Chad Orzel
Yale University

“Squeezed States in a Bose-Einstein Condensate”
Dr. James Lerczak
Woods Hole Oceanographic Institution

“Oceanic Internal Waves: From Internal Tides to Internal Surf”
Dr. Daniel Butts
Harvard Medical School

“How Does Early Activity in the Retina Guide Brain Development?”

OFF-CAMPUS PHYSICS PRESENTATIONS
Professor Daniel Aalberts

“Ultrafast Photoisomerization: The First Step in Vision”
Colgate College

“A Simple Scenario for Ultrafast Photoisomerization”
Rockefeller University
Professor Sarah Bolton,

“High Order Correlations in Semiconductor Nonlinear Optical Response”
Invited talk at November Meeting of the Materials Research Society, Boston, MA - November 2000
“Sixth-order Coulomb Correlations Identified in a Semiconductor Single Quantum Well”
Quantum Electronics and Laser Science Conference, Baltimore, MD - May 2001 (invited talk)

“Ultrafast Spectroscopy of Nanostructures: Windows into Many-Body Interactions”

Dartmouth College - Condensed Matter Seminar - October 15, 2000

“Squeezing Semiconductors: What Ultrafast Measurements Tell Us about Mesoscopia”

Mt. Holyoke College - Physics Department Colloquium - November 20, 2000

“Squeezing Semiconductors: What Ultrafast Measurements tell us about Mesoscopia”

Amherst College - Physics Department Colloquium - March 5, 2001
Professor Kevin Jones

“Hyperfine Structure of High Lying Vibrational Levels in the Na₂ 1_g (3S+3P_3/2) State Observed by Photoassociation of Cold Atoms” (with Ginel Hill ’00 and others)
Meeting of the American Physical Society Division of Atomic Molecular and Optical Physics, Storrs, CT

“Observation of Na₂ gerade Levels Dissociating to the 3P+3P Atomic Limit by Two-color Photoassociation Spectroscopy” (with F. Fatemi and P. D. Lett)
Meeting of the American Physical Society Division of Atomic Molecular and Optical Physics, Storrs, CT

“Ultracold Atom Collisions Probed with Short Laser Pulses” (with F. Fatemi and P. D. Lett)
Meeting of the American Physical Society Division of Atomic Molecular and Optical Physics, Storrs, CT

“Photoassociation Spectroscopy of MilliKelvin Sodium Atoms” (with F. Fatemi and P. D. Lett)
Workshop on Prospects of Cold Molecules II, Schloss St. Martin, Graz Austria

“Observation of Optically Induced Feshbach Resonances in Collisions of Cold Atoms” (with F. Fatemi and P. D. Lett)

Workshop on Prospects of Cold Molecules II, Schloss St. Martin, Graz Austria

“The Hot and Cold Show”

Williamstown Elementary School (Third grade Science Night, Ms. Bucky’s 5th grade class and Mrs. Simon’s Kindergarten class)

“Production of Translationally Cold Na₂ Molecules in High Vibrational Levels of the Triplet Ground State”

Meeting of the American Physical Society Division of Atomic Molecular and Optical Physics London, Ontario

May 2001
Professor Protik (Tiku) Majumder

“Diode Lasers, Thallium Atoms, and Tests of Fundamental Physics”

College of the Holy Cross (department colloquium), June 27, 2000

“Precise Atomic Structure Measurements in Thallium at 378 nm Using a Frequency-doubled Diode Laser”

APS Division of Atomic, Molecular, and Optical Physics Meeting (contributed talk), London, Ontario, CA, May 15, 2001
Professor William Wootters

“Quantum Entanglement as a Resource for Communication”

University of Texas at Austin, University of Virginia, SUNY Stony Brook

Max Planck Symposium, University of Puget Sound

“Sharing Entanglement”

University of New Mexico/Los Alamos Joint Seminar

International Conference on Quantum Information, University of Rochester

“Sending Classical Bits through Quantum Channels”

Dartmouth College

Professor Daniel Aalberts

“Phase Transitions and Renormalization Group Theory”

Summer research program - summer 2000
Professor Protik (Tiku) Majumder

“Diode Lasers, Thallium, and the Next Decimal Place”

Summer Science Lecture Series, June 27, 2000
Professor William Wootters

“Why Things Fall”

Physics Department Summer Seminar

“Are Quantum Particles Monogamous”

Bronfman Lunch Talk