Thomas Purdy
University of Pittsburgh, PA·Physics·Early-career
Some of physics' biggest open questions might leave signatures too faint to detect: extremely tiny forces. Certain proposed kinds of dark matter, the unseen mass that holds galaxies together, could push on objects very gently.
- Fields
Physics
Engineering
- Topics
optomechanics
quantum noise
quantum backaction
- Grants
- 1 known grant, through Jan 2027
What they work on
- 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.
- Apply the quantum-enhanced optical lever to vibrating strings held under high tension that lose very little energy, so they can sense strain, gravity and magnetic fields beyond standard quantum limits.
- Anchor a string sensor to a larger test mass and study the quantum limits on measuring strain caused by the mass's motion.
- Use the string sensor measurements to constrain beyond-standard-model physics, including exotic quantum decoherence models and ultralight scalar dark matter.
More about the research
So could proposed effects that destroy quantum behavior, such as an object being in two places at once. Ultrasensitive mechanical sensors could detect these forces or rule them out. At much smaller scales, they could even feel the magnetism of single atoms. However, the best sensors are now hitting limits set by quantum mechanics itself. Observing an object with light gives it random kicks from bouncing photons, called backaction, and these kicks hide the motion being measured.
Why it matters
The sensing methods could eventually help detect gravitational waves with quantum-enhanced sensitivity. They could also support nanoscale force microscopy and nanoscale magnetic resonance imaging (MRI) of biological molecules or semiconductor devices that conventional techniques cannot image, as well as storing and converting quantum states for quantum information processing. In the meantime, the measurements could place limits on dark matter and on new physics.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Andrew Geraci
Northwestern University, IL·Physics
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.
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.
Paul Hess
Middlebury College, VT·Physics
Measure how strongly a single trapped ytterbium ion couples to a nearby bulk lead zirconate titanate piezoelectric resonator, detected as faster heating of the ion's motion on resonance.
The school
University of Pittsburgh: 83 labs on PI Pages, $1.5B a year on research, 403 research doctorates a year.
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