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The
Physics Department strongly encourages physics
majors to work on independent projects
throughout their time at Wellesley. There are
many opportunities for students to do research
with faculty on campus. Students can receive
academic credit during the term by electing to
do either a Physics 250 (usually most
appropriate for First Year and Sophomore
students) or a Physics 350 (usually most
appropriate for Juniors and Seniors).
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Seniors
who are invited to do so may elect to do a year
long Honors Thesis.
There
are also many possible sources of funds for
students who would prefer to be paid rather than
receive academic credit for the time they spend
working on research projects. There are a number
of programs to finance summer research projects,
and most students who wish to do so are able to
obtain funding for housing and an hourly stipend
for two months of summer research. WinterSession
is another good time to work on an independent
project. Finally there are many opportunities
for students to engage in research off campus,
particularly during the summer
months.
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The
best way for a student to get started on independent work
on campus is to talk to individual faculty members about
possible projects. The research expertise in the
Department is spread over a variety of fields in physics,
including experimental research in atomic, optical, and
molecular physics, signal analysis and machine perception
of music, the physics of complex fluids, robotics and the
development of designed-based educational technology,
theoretical research in laser spectroscopy and cavity
quantum electrodynamics, and theoretical condensed matter
physics. We certainly don’t expect students to be
already knowledgeable in our fields of research! We will
introduce you to our research programs. On the
following pages you will find descriptions of the
research interests of the professors in the Physics
Department, along with listings of possible projects for
students. You can find more information about our
individual research projects on the Physics
Department’s faculty
webpage.
You
can also begin participating in the research process more
generally by attending the Department’s informal
"brown bag" seminar (alternate Mondays; 12:30 —
1:20), a lunch meeting where students and faculty discuss
ongoing projects and topics of current interest. You
should also be aware that we welcome student suggestions
for independent projects, and we are willing and
interested in supervising student work in areas outside
of our professional specializations. If you have a good
idea, or the beginnings of a good idea, come and speak
with us! Two excellent resources for projects appropriate
for undergraduate physics students are the American
Journal of Physics and Physics World, journals
(both are in the Science Library) aimed at a general
physics audience — from undergraduates through Ph.D.
researchers. A third resource is your physics texts. An
in-depth study of a topic presented in class can serve as
an excellent introduction to research in
physics.
Finally,
there are many fine opportunities for undergraduates to
work in off-campus research environments. The Wellesley
College Society of Physics Students website maintains
links
to a number of summer research programs including the
National Science Foundation’s Research Opportunities
for Undergraduates (REU) program. The Physics Department
also maintains a collection of brochures and electronic
information on summer programs.
Off-campus
Research Opportunities
Recent
Student Research Projects
Research
Opportunities with Physics Faculty
Robbie
Berg
Judith
Brown
Ted
Ducas
Yue Hu
Courtney Lannert
Bill
Quivers
Glenn
Stark
Robbie
Berg
Professor
of Physics
There
are two main categories of projects that I am most
interested in working on with students:
Laser
Cooling and and Trapping of Neutral Atoms. Along with
Wellesley physics faculty members Glenn Stark and Tom
Bauer, I have been working with a number of students
(most recently Sheila Dwyer '05, Seila Selimovic 04, and
Kate Kwasnik (Boston College '04)) on a project that uses
laser light to trap and cool rubidium atoms. In this
experiment, which is being carried out in Wellesley's
Laser Lab, we use a technique known as "optical molasses"
in which laser beams whose wavelength has been very
precisely selected are used to create a region in space
where rubidium atoms feel a friction-like force from the
light no matter which way they move. The atoms are thus
slowed down to a near standstill, dramatically lowering
the temperature of the gas. With this technique we are
hoping to obtain temperatures less than a thousandth of a
degree above absolute zero.
Programmable
Bricks. In 1996 and again in 2000 I was a Visiting
Professor in The Lifelong Kindergarten Group at the MIT
Media Lab and I continue to collaborate closely with the
group, exploring how new technologies can enable new ways
of thinking, learning, and designing, with a particular
emphasis on learning about scientific and mathematical
ideas. Our group creates new "tools to think with" and
explores how these tools can help bring about change in
real-world settings, such as schools, museums, and
under-served communities. For example, we are developing
"computational construction kits" (including programmable
LEGO bricks), and studying how and what people learn when
they design and invent with these new technologies. I
have workedon the creation of a new generation of
"programmable bricks" called Crickets. The LEGO
Mindstorms product, which was released in the Fall of
1998 by the LEGO company, was inspired by our group's
work on programmable bricks. With Mitchel Resnick (MIT)
and Mike Eisenberg (Colorado), I led an NSF-funded
project called Beyond Black Boxes, in which children are
using Crickets to design their own instruments for
scientific investigations.
Please
click here for
more details.
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Judith
Brown
Professor of Physics Emeritus
My
general interest is in machine perception of music, that
is to what extent is the information contained in musical
signals and musical scores accessible by computer. My
initial interest in this area was in pitch tracking by
computer both in the frequency domain and in the time
domain and in pitch perception by humans. Other problems
I've studied have included the use of autocorrelation to
determine musical meter, pitch perception of frequency
modulated musical signals by skilled performers,
harmonicity of musical instruments, limits of accuracy in
performances and in pitch perception by skilled
musicians, and musical instrument identification. Most
recently I have used a mathematical technique called
Independent Component Analysis (ICA) to show that it can
be used for the analysis of audio data. Using ICA we were
able to extract the components of a large number of
trills and show that trill rates could be obtained
automatically. I am currently working on an inverse
Constant Q Transform, which will enable us to listen to
the separated components in a trill or any other musical
passage previously subjected to an ICA calculation.
Publications
are listed on my Wellesley web page.
Current
Research Projects:
Visualization
of phase changes for the Fourier transform: Problems
with calculation and visualization of phase changes of
signals in the past have arisen from unwrapping the
phase, that is its inherent uncertainty modulo 2 pi. This
can be circumvented using a color representation which is
periodic with period 2 pi, and this is being explored
using matlab surface graphs where the curves correspond
to Fourier amplitudes and the color to phase. It would be
very interesting to find phase behavior which is specific
to particular musical instruments or families of
instruments.
Independent
Component Analysis of piano trills: For many years
speech and music researchers have sought to analyze
signals from multiple sources. Recent calculations on
Blind Source Separation with multiple microphones have
used a mathematical technique very similar to a matrix
solution of the eigenvalue problem in quantum mechanics
called Independent Component Analysis (ICA). I am
collaborating with Paris Smaragdis of the MIT Media Lab
on an extension of this technique using a single
microphone, but with multiple analysis frames. We have
been very successful in separating the notes in piano
trills and have written a paper on these results.
Inversion
of Constant Q Transform: The Constant Q Transform is
similar to the Discrete Fourier Transform, but is
calculated at frequencies which in a constant ratio to
each other rather than multiplied by integers. This leads
to problems for the inversion back to the time domain
since there is no mathematical theorem on which to base
the inversion. A simple extension of the inverse DFT to
the exponential domain works somewhat, but is far from
perfect. Work is in progress on improvement of an
algorithm for the inverse transform.
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Ted
Ducas
Professor of Physics
My
research in Physics has been largely in the area of laser
spectroscopy of atoms and molecules. At Wellesley I have
worked with students on a wide variety of research
projects reflecting their particular interests and the
extensive range of the applications of physics. In atomic
physics and modern optics students have worked on such
topics as construction of tunable lasers, optogalvanic
atomic spectroscopy, atomic radiative lifetimes, and
pulse propagation through optical fibers.
A
number of students have worked on projects in biophysics
or biomedical engineering. Some of this work has been
jointly supervised with faculty in the Harvard-M.I.T.
Health Sciences and Technology Program. One student
project involved construction of an optical system as
part of a new technique being developed at the Harvard
School of Public Health aimed at measuring oxygenation of
hemoglobin during operations. An honors student worked
with me and a colleague at the Harvard Medical School
investigating possible resonance effects of electric
fields on cell membranes.
Recent
and Current student projects:
Current
student work centers around the design, construction and
use of optical tweezers. Optical tweezers utilize the
light forces generated by tightly focused laser beams to
manipulate small particles - including single biological
cells. Students have constructed a visible tweezers
apparatus using a red laser and an infrared tweezers
system for studying biological samples. They have
calibrated the strength of the tweezers' trapping
strength as a basis for measurements of forces associated
with singled-celled animals, sticking forces between
cells and surfaces, and the movement of cells through
fluids. Last year a student developed a double tweezers
system to allow for relative motion between two separate
traps and expand the repertoire of our measurements.
Video
Physics Projects:
There
are also opportunities to work with video apparatus and
computer analysis to make measurements on physical
systems. These projects are centered mostly on
educational goals to connect physics with real-world
phenomena. Possibilities include: measurements of
phenomena in different reference frames, measurements and
representation of three-dimensional motion, studies of
the Doppler Effect and time-lapse video.
Science
Center Interactive Exhibits:
Another
area where students can get involved is in the design and
construction of interactive physics displays for the
Wellesley Science Center. Display opportunities include
demonstrating acoustic focusing with large parabolas,
creating a color wall with red green and blue lights and
designing an optimum rolling race.
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Yue
Hu
Associate Professor of Physics
My
research interests fall into the general category of
complex fluids. The systems that I have studied are
colloids -- mixtures of small undissolved particles
suspended in other surrounding substances. I have
conducted experiments, theoretical work, and computer
simulations on the dynamic and dielectric properties of
colloids in alternating electric fields. For a more
detailed description of my research, please visit my
website:
http://www.wellesley.edu/Physics/Yhu/hu.html
Current
Student Projects
1.
Gels and Fractals. Gels are formed when particles
in a colloidal suspension interact with each other strongly enough
to form a
mechanical network. We have discovered that mixtures of silica
particles in silicone oil, initially a gel, become a free-flowing
liquid in about 2 weeks of time. We are conducting experiments
to investigate why this gel transforms into a fluid. What we
will learn from this system will contribute to the study of gel-fluid
phase transition in general. Because silica and silicone oil
are widely used in the modern rubber industry, our understanding
the aging behavior of this system also has important industrial
applications.
We are also interested in the electrical properties
of the silica-silicone oil system. We have found that the dielectric
spectrum of this
system changes little over time, in contrast to the drastic change
in the mechanical properties. This apparent decoupling between
the mechanical properties and the electrical properties is quite
intriguing. Experiments are currently being carried out to investigate
a possible fractal behavior in the electrical properties of these
gels.
2.
Electrorheological Fluids. When small particles are suspended
in an insulating fluid, the viscoelastic properties of the suspension
are very sensitive to an external electric field applied to the
fluid. Without the field, the fluid flows like a normal liquid.
When a strong field is applied, the fluid can become very viscous
and almost solid-like. We are conducting computer simulation
work to investigate how the rotational motion of small particles
under shear affects the polarization of these particles in an
alternating electric field and how this flow-modified polarization
affects the viscosity of the suspension.
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Courtney
Lannert
Assistant Professor of Physics
My
research focuses on collective properties of electrons in
condensed matter systems. Many highly studied materials
(such as the high-temperature superconductors) seem to
exhibit properties that cannot be explained by the
simplest, non-interacting electron models. Theoretically,
including electron-electron interactions into models of
these systems can be quite difficult but can also lead to
fascinating properties. In my research, I hope to
understand better the experimental consequences and
physical meaning of these theoretical ideas.
One
interesting consequence of non-negligible
electron-electron interactions in many materials is
magnetism. Using numerical methods on simple "spin"
systems, one can model the behavior of magnetic systems
quite well. I am also working to develop simple numerical
methods for analyzing many-body wavefunctions. For
strongly-correlated electron systems, the many-electron
wavefunction displays cooperation between the electrons.
By choosing a wavefunction with a certain type of
cooperation, one can use variational methods to determine
whether this behavior "matches" a certain physical
system. This is a particularly direct approach, which
cuts to the heart of the question: "what are the
electrons doing in these mysterious materials?"
For
this upcoming summer, I am looking for students
interested in using a numerical technique called
Monte-Carlo simulation to explore both the magnetic
properties of simple spin systems and test wavefunctions
for the high-temperature superconductors. No previous
knowledge of this numerical method or the physical system
is necessary.
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William
Quivers
Associate
Professor of Physics
I
am a theorist whose general area of research is laser
spectroscopy of atoms. Specifically, I have developed a
model that describes laser optical pumping in multilevel
atomic systems that undergo velocity changing collisions.
This model has been employed in the in the sub-field of
laser-nuclear science to study the properties of excited
nuclei. For example, it’s been used in laser-induced
nuclear orientation experiments, which produced
first-time measurements of the nuclear magnetic and
electric quadrupole moments of the 1- m s rubidium-85
isomer. In addition, it has been utilized in atom-atom
collision studies.
Most
recently, I have been working in the field of cavity
quantum electrodynamics. In particular, I’ve worked
with Professor Michael Feld’s single-atom laser
group at MIT. This group, in fact, was the first to
develop such a device. Presently, I’m working on
calculating the single-atom laser lineshape.
In
the past, I have had students working on various models
of elastic atomic collisions. At the moment, though,
I’m looking for a student(s) who might be interested
in performing calculations in connection with the
Department’s laser-cooling experiments.
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Glenn
Stark
Professor
of Physics
My
primary field of research is experimental molecular
spectroscopy. I record and analyze the laboratory
absorption and emission spectra of simple molecules
(diatomics and the occasional triatomic molecule) that
are of interest to astronomers and to scientists studying
the earth’s and other planets’ atmospheres.
Most of my work involves the study of "vacuum
ultraviolet" (wavelengths between 100 — 200 nm) and
"extreme ultraviolet" (50 — 100 nm) transitions in
molecules; these relatively high-energy transitions often
cause a molecule to dissociate or ionize — processes
that are of importance in understanding the photophysics
and photochemistry of the environments in which the
molecules are found (e.g, interstellar gas clouds,
planetary atmospheres, the earth’s upper
atmosphere). I am also active in the field of "fourier
transform spectroscopy" of molecules, and I have a
continuing interest in laser spectroscopies of molecules.
Some of the more technical details of my research are
described in my Wellesley Physics Department WEB page,
along with a listing of recent publications.
Student
Projects
1.
These days I am working on two projects funded by NASA,
involving the measurement and analysis of ultraviolet
transitions in molecular nitrogen (N2) and
sulfur dioxide (SO2). There are some different
options for student participation:
(a)
I have a lot of data from recent measurements on the
N2 molecule that need to be reduced and
analyzed. In the recent past I’ve paid students
an hourly wage to do some of this work. I expect that
I’ll have the money to continue this. A
reasonable time commitment for this sort of work is 5
— 10 hours/week.
(b)
It is certainly possible to carve out a self-contained
350 or 370 project for a student interested in
learning more about my NASA-supported work. The work
would be mainly computational, as most of the relevant
data has been collected. I periodically travel to
Japan to use a "synchrotron light source" for some of
my measurements; it may be possible to find the
funding to bring one or two students along to assist
in the measurements.
2.
In the last four years I have been collaborating with
Professor Robbie Berg and Tom Bauer of the Physics
Department in the development of a laser cooling and
trapping apparatus. By combining faculty and student
resources, we have developed an ongoing project in basic
atomic and optical physics that can involve students and
faculty over a number of years. In the past four summers,
ten students have worked on this project. We have
successfully trapped and cooled a gas of rubidium atoms
to a temperature in the range of 0.0002 K (that's 200
millionths of a degree above absolute zero!). There is
much work to be done, and there is room for more student
participation in the coming year.
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