DEPARTMENT OF PHYSICS AND ASTRONOMY

Atomic, Molecular, and Optical

Areas of Research

Optics
We control the properties of light and use it to manipulate matter on length scales ranging from individual molecules, through nano- and micro-particles (including cells), up to the macroscopic level. Areas of interest include coherent control of light (Seideman), non-linear optics, excitonics, and plasmonics, (Kumar, Ketterson, Shahriar), non-classical states of light (Kumar),  quantum opto-mechanics (Geraci), ultra-sensitive force detection and experimental gravitation (Geraci), and biophotonics (Ketterson, Jacobsen).

Quantum Computing and Cryptography
We address fundamental and applied questions concerning utilization of quantum-mechanical properties of light and matter in the field of information processing. Our research includes investigation of photon entanglement over fiber networks (Kumar), and quantum computing in atom traps (Shahriar).

Faculty

Gerald Gabrielse (Arrives 2017) [Gabrielse Research Group] 

Establishing new paradigms for understanding physical reality requires devising and implementing methods to test their predictions.  Professor Gabrielse’s group probes the predictions, symmetries and extensions to the standard model with exquisite sensitivity, with methods that derive their sensitivity from precision rather than energy.  Research projects include using trapped particles and molecular beams to test Quantum Electrodynamics, the CPT theorem, and time-reversal symmetry at the most stringent levels.  Professor Gabrielse is a member of the Center for Fundamental Physics at Low Energy (CFP).  Email Gerald Gabrielse

Andrew Geraci [Geraci Research Group]

Several small-scale, tabletop low-energy experiments are poised to discover a wide range of new physics beyond the Standard model, where feeble interactions require precision measurements rather than high energies. In our atomic-molecular and optical (AMO) physics group, we employ high-Q resonant sensors for ultra-sensitive force and field detection in searches for new physics. Using laser-cooled optically-trapped dielectric nanospheres, we have demonstrated calibrated force sensing at the zeptonewton (10−21 N) scale. We aim to apply this excellent force sensitivity to search for deviations of the Newtonian gravitational inverse square law at micrometer range, in a regime where several theories predict possible new signatures.  We have also started work on The Axion Resonant InterAction Detection Experiment (ARIADNE), which will use nuclear magnetic resonance to search for the QCD axion, a notable Dark Matter candidate.  Email Andrew Geraci

Chris Jacobsen [Jacobsen Research Group] 
Professor Jacobsen's research group is developing novel methods, instruments, and analysis approaches for x-ray imaging, and applying them to problems in biology and environmental science. This research makes use of the Advanced Photon Source (APS) at nearby Argonne National Laboratory, where Jacobsen holds a joint appointment. The APS is a leading facility for x-ray research, and provides unique opportunities for Northwestern students to be at the forefront of developing methods for nanoscale imaging of how metals regulate cellular functions, how environmental contaminants can be remediated, and improved batteries and solar cells can be developed.  Email Chris Jacobsen

John Ketterson
For a number of years the Ketterson group has been studying the properties long-lived excitons at high density in materials like cuprous oxide with special emphasis on macroscopic coherence displayed by exciton polaritons and expected for an excitonic Bose-Einstein condensate. Other interests include i) laser tweezers (with special emphasis on potential biological applications), ii) plasmonic properties of metal films and nanostructures and iii) studies the non linear optical properties of a wide variety of materials including semiconductors and organic chromophors.  Email John Ketterson

Tim Kovachy [Kovachy Research Group] 
The Kovachy Group uses the quantum mechanical, wavelike nature of atoms cooled to a billionth of a degree above absolute zero to measure forces extremely precisely. These atomic sensors can measure forces 100 billion times smaller than the force exerted by Earth’s gravity on a single atom. We utilize this exceptional sensitivity to search for new fundamental particles, including those potentially relating to dark matter or to the extra dimensions that can arise in string theory. As a member of the Mid-band Atomic Gravitational Wave Interferometric Sensor (MAGIS) collaboration, the group is working towards the construction of an atomic gravitational wave detector that would be complementary to LIGO.  Email Tim Kovachy

Prem Kumar [Kumar Research Group] 
Professor Kumar's research spans the following three inter-related areas within classical and quantum optics: Quantum Fiber Optics-generation and distribution of quantum entanglement over the fiber channel and quantum cryptography over fiber lines; Optical Communications-novel optical amplifiers and devices for terabit/s communications; Nonlinear and Quantum Optics-applications of novel quantum states of light such as squeezed and twin-beams states in precision measurement and imaging systems.  Email Prem Kumar

Brian Odom [Odom Research Group] 
Professor Odom’s group performs experiments with milliKelvin molecular ions held in radio-frequency traps.  Research projects include development of techniques to control and read out the internal quantum states of single trapped molecular ions, a search for time-variation of fundamental constants, and studies of quantum effects in chemical reactions below 1 Kelvin.  Professor Odom is a member of the Center for Fundamental Physics at Low Energy (CFP).   Email Brian Odom

Tamar Seideman [Seideman Research Group]
Professor Seideman’s group performs theoretical research at the broad interface between molecular physics, chemical dynamics and material research. Specific research interests include quantum transport, molecular electronics, current-driven nanochemistry and molecular machines; nanoplasmonics and light manipulation in the nanoscale; coherent control and coherence spectroscopies in isolated molecules and in dissipative media; the interaction of matter with intense laser fields; and mathematical method development.  Email Tamar Seideman

Selim Shahriar [Shahriar Research Group] 
Professor Shahriar's research activities include the following areas: superluminal gyroscopes for measuring Lense-Thirring rotation as a test of General Relativity, white light cavities for enhancing the sensitivity of gravitational wave detectors, quantum computers using trapped atomic ensembles, ultra-low light level nonlinear optics using nanofibers and atoms for switching and quantum logic, and holographic and polarimetric image processing.  Email Selim Shariar

Programs

The Center for Fundamental Physics at Low Energy (CFP)
The Center for Fundamental Physics at Low Energy (CFP for short) is a long-term initiative of the Northwestern Department of Physics and Astronomy. The faculty members, graduate students and undergraduates associated with the CFP, along with CFP fellows, specialize in small-scale, low-energy experiments to investigate the particles, interactions, and symmetries of the universe - to test and help develop our most fundamental theoretical descriptions.   A weekly CFP colloquium features the most exciting international developments in relevant atomic, molecular, and optical physics, along with related developments in high energy physics, astrophysics, and new detector technologies.  Associates of the CFP, researchers from Northwestern and neighboring institutions who broaden the CFP community by their participation in the CFP colloquium, help select colloquium topics and speakers. The CFP also encourages interdisciplinary activities that reflect upon, illuminate and reveal the assumptions, implications and methods of fundamental physics