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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:1
UID:UW-Physics-Event-9401
DTSTART:20250919T150000Z
DTEND:20250919T160000Z
DTSTAMP:20260413T084034Z
LAST-MODIFIED:20250916T142626Z
LOCATION:5280 Chamberlin
SUMMARY:Spin-Squeezed Atomic Clock with Precision Beyond the Standard 
 Quantum Limit at the 10⁻¹⁸ Level\, Atomic Physics Seminar\, Joons
 eok Hur\, University of Colorado Boulder
DESCRIPTION:Optical atomic clocks (OACs)\, utilizing optical transitio
 ns in atoms as a timebase\, have achieved unprecedented precision and 
 accuracy in scientific measurement\, offering new frontiers in metrolo
 gy and fundamental physics.<br>
\n<br>
\nThe precision of state-of-the
 -art OACs has reached the standard quantum limit (SQL)\, the fundament
 al bound set by quantum projection noise in measurements on uncorrelat
 ed atoms. While increasing atom numbers can statistically suppress thi
 s noise\, it also introduces unwanted atomic interactions that comprom
 ise clock accuracy. Engineered entanglement between atoms can overcome
  the SQL\, and atomic clocks with spin-squeezed states have demonstrat
 ed improved precision with various platforms. However\, quantum advant
 age in entanglement-enhanced clocks\, surpassing the best precision of
  conventional OACs\, has yet to be achieved.<br>
\n<br>
\nIn this talk
 \, I will present our spin-squeezed optical lattice clock that achieve
 s precision beyond the SQL at the 10⁻¹⁸ level\, representing a si
 gnificant step toward quantum advantage in optical clocks. We squeezed
  the collective projection noise of 30\,000 atoms by 7.1(1.0) dB using
  quantum nondemolition measurements mediated by strong atom-cavity cou
 pling. Improved motional control preserves clock-state coherence\, res
 ulting in a 5.1(1.0) dB metrological enhancement. A synchronous compar
 ison between two independent spin-squeezed clock ensembles demonstrate
 s a 2.0(2) dB improvement beyond the SQL\, reaching a fractional insta
 bility of 1.1×10⁻¹⁸.<br>
\n<br>
\nThis work marks a milestone to
 ward quantum-enhanced timekeeping and provides a promising platform to
  explore the interplay between gravity and quantum entanglement.
URL:https://www.physics.wisc.edu/events/?id=9401
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