Research Areas

We build and refine the instruments that turn faint ripples in spacetime into discoveries. The Laser Interferometer Gravitational-Wave Observatory measures displacements far smaller than a proton — a feat that demands relentless attention to every source of noise, drift, and instability. Our group works at the Hanford and Livingston sites, diagnosing sensitivity limits and deploying fixes that push the detectors closer to their quantum and thermal noise floors. We also work in lab spaces at Caltech, including the 40-meter LIGO prototype at the Caltech campus.

Summer students help build and upgrade the hardware and controls that make gravitational-wave interferometers work: lasers, optics, vacuum, suspension, and commissioning tools for current and next‑generation detectors.

The mirrors in LIGO are among the most precisely controlled objects on Earth — seismically isolated, suspended as pendulums, and cooled by radiation to suppress every conceivable source of mechanical noise. Yet the dominant noise source in the most sensitive frequency band (50–300 Hz) is a few micrometers of dielectric coating on each mirror surface. These thin films — alternating layers of tantala (Ta₂O₅) and silica (SiO₂) deposited by ion-beam sputtering — are essential for achieving >99.9995% reflectivity (transmission below 5 ppm), but their internal mechanical losses couple to the thermal bath and produce Brownian displacement noise that sets the floor of the detector.

Summer students will help develop and test thin film coatings to help reach design goals for the next generation of gravitational-wave instruments.

General relativity and quantum mechanics are the twin pillars of modern physics, yet they remain fundamentally unreconciled. We pursue tabletop experiments that probe this frontier — not by building particle accelerators, but by pushing optomechanical systems to regimes where quantum and gravitational effects might intersect.

The GQuEST experiment at Caltech uses a photon-counting interferometer to search for geontropic spacetime fluctuations, testing the Planck-scale fluctuations predicted by holographic vacuum-entanglement (Verlinde–Zurek) models (Vermeulen et al. 2025).

Students will work in laboratory spaces with optics to design, build, and test instruments for tests of quantum gravity and other fundamental physics.

Future gravitational-wave detectors will rely on high levels of squeezed light and laser power to achieve unprecedented quantum-limited sensitivities. Harnessing both, the next-generation U.S. detector, Cosmic Explorer, aims to achieve ten times the sensitivity of LIGO today, extending the gravitational-wave detection horizon to almost the edge of the observable universe. However, high laser power imposes fundamental limitations due to thermally-induced distortions of the optics, which drive mode-mismatch between the interferometer's laser cavities and degrade its sensitivity to gravitational waves.

We develop new laser wavefront sensing and control technology to overcome these limits. The LIGO interferometers rely on a complex system of adaptive optics to finely control the wavefronts of the propagating laser beams. Extending this system's capabilities, by integrating new technologies to sense wavefront errors and apply higher-order corrections, will dramatically reduce optical losses in gravitational-wave interferometers, pushing theirpower storage capacity toward the Megawatt scale. Our group works in dedicated adaptive optics development facilities at UC Riverside.

Students will work in optics laboratories to design, build, and test prototype mode sensing and control technology for LIGO and Cosmic Explorer.

One of the primary goals in GW astronomy is to identify weak signals in very noisy detector data. The inspiral and merger (coalescence) of compact stars (neutron stars and black holes) produce a GW signal that is well modeled using numerical simulations of General Relativity to predict the signal waveform. We search for these signals using matched filtering. Matched filter searches on LIGO data use hundreds of thousands of waveform models that span different object masses and spins. To date, dozens of such signals have been detected in this way.

In addition to search pipelines, our group members work on developing catalogs of binary mergers, which can be used to study merger rates and populations, binary formation mechanisms, and tests of general relativity.

Students interested in searching for compact binaries can study the origin, evolution, and morphology of these signals to learn as much as possible about their implications for astrophysics and cosmology.

In the new era of gravitational wave astronomy, our primary goal is to measure source parameters and draw astrophysical inferences from observed signals, as accurately as possible. To do this effectively, we require an accurate estimate of the calibrated strain, due to gravitational waves passing through our detectors. This is especially important for testing General Relativity using well modeled waveforms. Students who work in LIGO calibration will combine precision controls engineering with computationally efficient signal processing to provide such data in real time.

Interest in / experience with signal processing and Python is recommended; students will also learn some techniques from controls engineering.

Some of the GW signals that LIGO detects, such as the binary neutron star merger GW170817, will have gamma-ray, X-ray, optical/infrared, radio, or neutrino counterparts. In many ways this can be thought of as witnessing the same event with several different senses. But for many compact binary source types, LIGO is the one to catch them first, locate the source in the sky, and inform astronomers where to point their telescopes. Students who get involved in multi-messenger astronomy will analyze data and develop software to learn as much as possible from joint observations with other telescopes scattered across the world and in space.

Interest in / knowledge of Python, signal processing, image processing, and Bayesian statistics is recommended.

Breakthroughs in physics are often made at extremes, and the weakest of all interactions -- gravity -- is no exception. General relativity is the prevailing theory of gravity, which describes gravitation as curvature in space and time rather than as a force. Since the early 20th century, tests of general relativity were all done using measurements of Solar System objects where gravitation is relatively weak. However, with every LIGO observation of extremely compact sources such as neutron stars and black holes comes a unique opportunity to test general relativity using extreme spacetime curvature, pushing the theory to its limits. Students who work on such projects will test this foundational principle of modern physics using the cutting-edge LIGO experiment.

Numerical relativity is a powerful tool for simulating the gravitational wave signatures of binary black hole mergers, as well as the recoil response of the system after merger. One key direction in current research is using simulations, population models, and observations of black holes to understand more about the evolution of black hole progenitor stars and binary black hole systems. Another direction is contributing to the body of waveforms that searches for modeled gravitational waves signals in LIGO data can draw on by improving the accuracy of phenomenological models and/or the efficiency of numerical simulations.

Interest in / experience with signal processing and Bayesian statistics are recommended; students will also learn a great deal about general relativity.