Physics

Students in physics will find opportunities for research in a number of areas where members of the faculty are currently active, including those listed below. Physics research at Caltech is often done in collaboration with scientists in the departments of applied physics, astrophysics, planetary science, engineering, chemistry, biology, and other departments, as well as with collaborators at other universities and laboratories. Additional research programs and more detailed information can be found on the Caltech physics department website.

• Experimental Elementary Particle Physics. Activities in elementary particle physics are aimed primarily at discovering new particles and interactions beyond the Standard Model (BSM) complemented by precision measurements of SM processes. Experimental efforts employ hadronic colliders and electron, muon, and neutrino beams at several international facilities. Current experiments include:
  • CMS searching for dark matter and other new particles and new symmetries up to the mass scale of several TeV at the Large Hadron Collider at CERN
  • the NOvA and DUNE long baseline experiments at Fermilab, studying the pattern of masses, mixing and CP violation in the neutrino sector
  • the Mu2e experiment, searching for physics beyond the standard model in charged lepton flavor violation
  • a nascent effort to search for accelerator production of dark matter called LDMX
  • the long-running SuperCDMS effort to directly detect scattering of galactic dark matter with normal matter.
• Theoretical Elementary Particle Physics. The particle theory group studies the unification of interactions based on string theory, the detailed properties of hadrons described by QCD, the quantum properties of black holes, the foundations of cosmology, including dark matter and dark energy, and other aspects of mathematical physics.
• Condensed-Matter Physics. Areas of interest include correlated electron systems, topological quantum matter, quantum dynamics, disordered systems, phase transitions, atomic and excitonic Bose condensation, nanomechanical and nanoelectronic systems, biosensors, quantum electromechanics, phonon physics, high-temperature superconductivity, graphene and carbon nanotube systems, quantum entanglement, dynamics of disordered systems, chaos, pattern formation, and systems far from equilibrium. Resources include numerous labs in the Caltech physics department, at the Kavli Nanoscience Institute at Caltech, and at the Jet Propulsion Laboratory.
• Quantum Optics and Information. Research on campus and at the Institute for Quantum Information and Matter at Caltech includes studies of the nature of quantum computation and quantum information, cavity quantum electrodynamics, algorithms and error correction techniques in quantum computation, and generally how quantum physics can be harnessed to improve the acquisition, transmission, and processing of information.
• Experimental Atomic/Molecular/Optical Physics. Experimental atomic, molecular, and optical (AMO) research at Caltech focuses on controlling and understanding complex quantum systems for a wide variety of scientific goals. Current experiments include building arrays of ultracold atoms to study quantum information, metrology, many-body physics, and simulation of condensed matter systems; precision measurements in cold and ultracold polar molecules to search for fundamental symmetry violations; engineering atom-light interactions in photonic crystals; quantum physics of mechanical devices, hybrid superconducting quantum circuits, and optomechanical sensors; neurophotonics and neuromolecular sensing; development of quantum networks and communication and addressing fundamental questions in quantum information. Many of these research strands are collaborative efforts supported by the Institute for Quantum Information and Matter.
• Nuclear Physics. The interests of the nuclear group focus on performing precision measurements to search for new physics beyond the Standard Model. In particular, precision measurements of free neutron decay allow sensitive searches for new physics, while measurements of the neutron electric dipole moment may help explain the dominance of matter over antimatter in the universe.
• Astrophysics. Research in this area covers a broad range of topics using observational tools covering the entire electromagnetic spectrum.
  • The high-energy astrophysics group at the Space Radiation Laboratory (SRL) uses X-ray and gamma-ray detectors aboard spacecraft and balloons to investigate energetic processes from compact astrophysical objects, including gamma-ray bursts from neutron-star and black-hole systems, supernova and hypernova dynamics, and the development of stars and galaxies in the early universe.
  • The cosmic ray group at SRL uses data from a variety of spacecraft to study the composition of energetic particles arriving from the sun, the local interstellar medium, and beyond, in order to understand the origin and acceleration of energetic particles in space.
  • The millimeter/submillimeter astronomy group, with collaborators at the Jet Propulsion Laboratory, studies the solar system, star and planet formation, the interstellar medium, galaxies, galaxy clusters, and the epoch of reionization using data from the Caltech Submillimeter Observatory (CSO) and other facilities. Future-oriented programs include the development of new superconducting detector technologies and instruments for use at these wavelengths, also in collaboration with JPL, and an effort to move the currently idle CSO to a new, more sensitive site.
  • The Galactic compact objects astrophysics group studies black holes, neutron stars, and white dwarf systems, including gravitational wave sources detectable by future space missions such as LISA. The group uses telescopes at Palomar, Kitt Peak and the Keck Observatory, as well as the radio telescopes of the NASA Deep Space Network.
• Theoretical Astrophysics. The TAPIR (Theoretical Astrophysics Including Relativity) group carries out research on an ever-changing list of topics, including planets; stars, neutron stars, black holes and their interactions; gravitational-wave astrophysics; cosmology; the formation of stars and galaxies; and numerical and analytical general relativity.
• Cosmology. The observational cosmology group explores the structure and dynamics of the early universe using precise measurements of the cosmological microwave background radiation and large scale structures from detectors on the ground, on balloons, and on spacecraft. Efforts to directly detect dark matter are also underway. These experiments include an active program of detector development in collaboration with scientists at the Jet Propulsion Laboratory. Theoretical studies seek to understand the large-scale structure of the universe, including the physical nature of dark matter and dark energy.
• Gravitational-wave Physics and Astrophysics. Observations from the (current) LIGO and (future) LISA projects are used to detect and analyze gravitational radiation to study a variety of astrophysical sources. Theoretical studies are aimed at developing sensitive data analysis techniques and calculating
  gravitational-wave signals from sources such as coalescing black holes and neutron stars.

The physics and astrophysics departments and laboratories are mainly housed in six buildings on campus: the Norman Bridge Laboratory, the Alfred P. Sloan Laboratory of Mathematics and Physics, the W. K. Kellogg Radiation Laboratory, the George W. Downs Laboratory of Physics, the C. C. Lauritsen Laboratory of High Energy Physics, and the Cahill Center for Astronomy and Astrophysics. Off-campus astronomical facilities include Palomar Observatory, the Keck Observatories, Owens Valley Radio Observatory, the Caltech Submillimeter Observatory (currently idle), and the Laser Interferometer Gravitational-wave Observatory (LIGO).