
NSF Org: |
PHY Division Of Physics |
Recipient: |
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Initial Amendment Date: | August 22, 2018 |
Latest Amendment Date: | June 26, 2020 |
Award Number: | 1806223 |
Award Instrument: | Continuing Grant |
Program Manager: |
John D. Gillaspy
PHY Division Of Physics MPS Directorate for Mathematical and Physical Sciences |
Start Date: | September 1, 2018 |
End Date: | August 31, 2023 (Estimated) |
Total Intended Award Amount: | $297,370.00 |
Total Awarded Amount to Date: | $297,370.00 |
Funds Obligated to Date: |
FY 2019 = $77,526.00 FY 2020 = $47,768.00 |
History of Investigator: |
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Recipient Sponsored Research Office: |
155 S PLEASANT ST AMHERST MA US 01002-2234 (413)542-2804 |
Sponsor Congressional District: |
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Primary Place of Performance: |
Amherst MA US 01002-5000 |
Primary Place of
Performance Congressional District: |
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Unique Entity Identifier (UEI): |
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Parent UEI: |
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NSF Program(s): | AMO Experiment/Atomic, Molecul |
Primary Program Source: |
01001920DB NSF RESEARCH & RELATED ACTIVIT 01002021DB NSF RESEARCH & RELATED ACTIVIT |
Program Reference Code(s): |
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Program Element Code(s): |
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Award Agency Code: | 4900 |
Fund Agency Code: | 4900 |
Assistance Listing Number(s): | 47.049 |
ABSTRACT
Some atoms and molecules have quantum states with properties that are particularly well-suited for timekeeping, for quantum information processing, or for tests of physical laws. This project focuses on molecular vibrations that are sensitive to fundamental constants such as the electron mass and the proton mass. These vibrations occur when atomic nuclei stretch and compress a chemical bond, and their vibration frequencies depend on the proton-to-electron mass ratio. This team will conduct a proof-of-principle experiment using vibrational states to search for time dependent changes in fundamental constants. Such changes are predicted by some models of quantum gravity or dark matter, but have not yet been detected experimentally. This project promotes the progress of science by developing new ways to study molecular vibrations as precision tests of fundamental physics. This research takes place at a liberal arts college where undergraduate students are involved in all aspects of the work. In addition to training the next generation of scientists, this work develops skills in experimental physics that are transferable to a wide array of future endeavors.
This project will investigate electric-dipole-forbidden vibrational overtones in trapped molecular ions. The team will drive an overtone as a two-photon transition in the diatomic oxygen molecular ion, which is of long-term interest as both an optical molecular clock and as a probe for time-variation of the proton-to-electron mass ratio. The nonpolar nature of the molecule suppresses systematic shifts related to electric fields, such as AC Stark shifts and blackbody radiation. A key tool for this work is a stable optical local oscillator that is referenced to a separate optical clock. To demonstrate the promise of this system, this team will reduce the uncertainty on an overtone transition frequency by several orders of magnitude and monitor it over the course of a year.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Physicists have highly refined models of the very small (quantum mechanics) and the very large (the gravitational theory of general relativity), yet there are open questions about how to combine them. We also see evidence for new forms of "dark" matter, including in our own galaxy such that it should be present right here in our own labs. Many models of quantum gravity and some models of dark matter predict effects that should be observable with very precise measurements of atoms and molecules. One of these predictions is that the proton and electron should change their masses over time.
This project developed tools to use molecules as probes of new physics. We focused on molecular vibration, the back-and-forth motion of two atoms as they stretch their chemical bond like a spring. In a review article, we described how molecular vibrations can be ideal probes for changes in the proton mass. We published a second article, identifying the particular molecule O2+ as an ideal choice for such a test.
We have focused our experimental efforts on that charged molecule. Its charge allows us to trap it in space, which affords more time for our measurements. This award enabled the development of a molecular beam source, which produces a cold sample of neutral O2 molecules. A laser ionizes the molecules, producing our desired O2+ with its vibration in the quantum ground state. Our trap includes atomic ions, which allows us to laser cool the motion of the atoms and molecules. At the end of the award, we have built a toolbox for using the molecules.
As part of the award, 17 undergraduates and one postdoctoral scholar have participated in the research. Six of the students wrote undergraduate honors theses. Each student worked closely with the Principal Investigator and was trained in laboratory techniques, data handling and analysis, the responsible conduct of research, and reading scientific literature. Many presented posters or gave public talks on their work, either on campus or at scientific conferences.
Last Modified: 11/20/2023
Modified by: David A Hanneke
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