Andrew Geraci
Northwestern University, IL·Physics
A tiny glass bead held in midair by a laser beam, with nothing touching it, becomes one of the most delicate force sensors available. Inside a high vacuum there is almost no friction to disturb it, so even an extraordinarily feeble push shifts its position measurably.
- Fields
Physics
Engineering
Materials Science
- Topics
optical levitation
optically trapped nanospheres
laser cooling
- Grants
- 3 known grants, through Jul 2027
What they work on
- Search for Yukawa-type deviations from Newtonian gravity at the 1-2 micrometer scale by measuring the displacement of a laser-trapped, laser-cooled nanosphere near a microfabricated silicon and gold source mass, accumulating about a million seconds of data.
- Continue characterizing vibrational, electromagnetic and systematic noise sources in the levitated-nanosphere gravity measurement, and develop new trapping and cooling methods including sympathetic cooling with cold atoms.
- Complete commissioning of the ARIADNE apparatus, which uses nuclear magnetic resonance on laser-polarized helium-3 nuclei near an unpolarized tungsten source mass to detect spin-dependent short-range forces mediated by axions.
- Build the data analysis pipeline for ARIADNE and produce a preliminary experimental limit on axion-mediated forces for axion masses between roughly ten micro-electron-volts and ten milli-electron-volts.
- Assess the commercial translation potential of the Opto-Levitated Force Microscope, a laser-levitated probe that senses surface topography and electric and magnetic fields, through structured interviews across the semiconductor and advanced materials industry ecosystem.
More about the research
Three projects build on this capability. Two use levitated or spin-polarized sensors to look for physics beyond the Standard Model, the current catalogue of particles and forces: deviations from Newton's law of gravity at micrometer distances, and a hypothesized particle called the axion. The third explores whether the same levitated-probe idea can become a practical instrument for inspecting surfaces in industry.
Why it matters
Searching for departures from Newtonian gravity at micrometer distances and for the axion probes two of the largest open questions in physics, the nature of gravity and the identity of dark matter, at a small fraction of the cost of a particle collider. On the applied side, a non-contact levitated-probe microscope could give semiconductor manufacturers, materials and nanotechnology labs, medical device and coatings makers faster failure analysis and tighter quality control over larger areas, which may translate into more reliable devices for consumers.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
I-Corps: Translation potential of an opto-levitated force microscope
NSF · Aug 2026 – Jul 2027
Collaborative Research: Axion Resonant InterAction DetectioN Experiment (ARIADNE) - a continuation proposal
NSF · Aug 2025 – Jul 2027
BSM-PM: Measuring Gravity at the Micron-Scale with Optically Levitated Particles: a Renewal Proposal
NSF · Aug 2024 – Jul 2027
Closest labs
David Tanner
University of Florida, FL·Physics
Complete commissioning of ALPS II and analyze its first science runs, which search for photons converting into axion-like particles or hidden photons that pass through a light-tight wall inside strong HERA dipole magnets.
Thomas Purdy
University of Pittsburgh, PA·Physics·Early-career
Show that a modified optical lever, which measures how a beam's angle changes when it reflects off a tilting surface, can gain more quantum information while reducing photon-kick backaction.
Benjamin Augenbraun
Williams College, MA·Physics
Measure the electronic, vibrational, rotational, and hyperfine (nuclear spin) structure of molecules pairing copper, silver, or gold with lead, using laser spectroscopy to see which wavelengths of light they absorb.
The school
Northwestern University: 71 labs on PI Pages, $1.3B a year on research, 536 research doctorates a year.
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