Clock precision beyond the Standard Quantum Limit at $10^{-18}$ level

Fuente: arXiv
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Autores principales: Yang, Y. A., Miklos, Maya, Tso, Yee Ming, Kraus, Stella, Hur, Joonseok, Ye, Jun
Formato: Preprint
Publicado: 2025
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author Yang, Y. A.
Miklos, Maya
Tso, Yee Ming
Kraus, Stella
Hur, Joonseok
Ye, Jun
author_facet Yang, Y. A.
Miklos, Maya
Tso, Yee Ming
Kraus, Stella
Hur, Joonseok
Ye, Jun
contents Optical atomic clocks with unrivaled precision and accuracy have advanced the frontier of precision measurement science and opened new avenues for exploring fundamental physics. A fundamental limitation on clock precision is the Standard Quantum Limit (SQL), which stems from the uncorrelated projection noise of each atom. State-of-the-art optical lattice clocks interrogate large ensembles to minimize the SQL, but density-dependent frequency shifts pose challenges to scaling the atom number. The SQL can be surpassed, however, by leveraging entanglement, though it remains an open problem to achieve quantum advantage from spin squeezing at state-of-the-art stability levels. Here we demonstrate clock performance beyond the SQL, achieving a fractional frequency precision of 1.1 $\times 10^{-18}$ for a single spin-squeezed clock. With cavity-based quantum nondemolition (QND) measurements, we prepare two spin-squeezed ensembles of $\sim$30,000 strontium atoms confined in a two-dimensional optical lattice. A synchronous clock comparison with an interrogation time of 61 ms achieves a metrological improvement of 2.0(2) dB beyond the SQL, after correcting for state preparation and measurement errors. These results establish the most precise entanglement-enhanced clock to date and offer a powerful platform for exploring the interplay of gravity and quantum entanglement.
format Preprint
id arxiv_https___arxiv_org_abs_2505_04538
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Clock precision beyond the Standard Quantum Limit at $10^{-18}$ level
Yang, Y. A.
Miklos, Maya
Tso, Yee Ming
Kraus, Stella
Hur, Joonseok
Ye, Jun
Quantum Physics
Atomic Physics
Optical atomic clocks with unrivaled precision and accuracy have advanced the frontier of precision measurement science and opened new avenues for exploring fundamental physics. A fundamental limitation on clock precision is the Standard Quantum Limit (SQL), which stems from the uncorrelated projection noise of each atom. State-of-the-art optical lattice clocks interrogate large ensembles to minimize the SQL, but density-dependent frequency shifts pose challenges to scaling the atom number. The SQL can be surpassed, however, by leveraging entanglement, though it remains an open problem to achieve quantum advantage from spin squeezing at state-of-the-art stability levels. Here we demonstrate clock performance beyond the SQL, achieving a fractional frequency precision of 1.1 $\times 10^{-18}$ for a single spin-squeezed clock. With cavity-based quantum nondemolition (QND) measurements, we prepare two spin-squeezed ensembles of $\sim$30,000 strontium atoms confined in a two-dimensional optical lattice. A synchronous clock comparison with an interrogation time of 61 ms achieves a metrological improvement of 2.0(2) dB beyond the SQL, after correcting for state preparation and measurement errors. These results establish the most precise entanglement-enhanced clock to date and offer a powerful platform for exploring the interplay of gravity and quantum entanglement.
title Clock precision beyond the Standard Quantum Limit at $10^{-18}$ level
topic Quantum Physics
Atomic Physics
url https://arxiv.org/abs/2505.04538