U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Physics

Time & frequency

Search Publications

Search Title, Abstract, Conference, Citation, Keyword or Author
  • Published Date
Displaying 1 - 25 of 271

High-Stability Single-Ion Clock with 5.5 x 10^-19 Systematic Uncertainty

April 21, 2025
Author(s)
Mason Marshall, Daniel Rodriguez Castillo, Willa Dworschack, Alexander Aeppli, Kyungtae Kim, Dahyeon Lee, William Warfield, Nicholas Nardelli, Tara Fortier, Jun Ye, David Ray Leibrandt, David Hume
We report a single-ion optical atomic clock with fractional frequency uncertainty of 5.5 x 10^-19 and frequency stability of 3.5 x 10^-16/sqrttau/s}, based on quantum logic spectroscopy of a single 27Al+ ion. A co-trapped 25Mg+ ion provides sympathetic

NIST Time and Frequency Bulletin

April 7, 2025
Author(s)
Kelsey Rodriguez
The Time and Frequency Bulletin provides information on performance of time scales and a variety of broadcasts (and related information) to users of the NIST services.

Cryogenic photonic resonator with 10-17/s drift

February 11, 2025
Author(s)
Wei Zhang, William Milner, Jun Ye, Scott Papp
Thermal noise is the predominant instability in the provision of ultrastable laser frequency by reference to a cavity. Reducing the thermal-noise limit of a cavity means either making it larger to spread thermal fluctuations, reducing the sensitivity of

Progress towards accuracy evaluation of NIST-F4 Cesium fountain clock

October 24, 2024
Author(s)
Vladislav Gerginov, Gregory Hoth, Thomas Heavner, Jeffrey Sherman
This work presents preliminary results towards the evaluation of the NIST-F4 Cesium Primary Frequency Standard. We present measurements of NIST-F4 frequency instability and evaluation of some of its systematic frequency shifts and shift uncertainties.

Cryogenic Sapphire Optical Reference Cavity with 1 x 10^-16 fractional instability

October 2, 2024
Author(s)
Jose Valencia, George Iskandr, Nicholas Nardelli, David Leibrandt, David Hume
The frequency stability of a laser locked to an optical reference cavity is fundamentally limited by thermal noise in the cavity length, caused by local thermal fluctuations of the strain and index of refraction of the cavity components. These fluctuations

Foundry manufacturing of octave-spanning microcombs

September 6, 2024
Author(s)
Jizhao Zang, Haixin Liu, Travis Briles, Scott Papp
Soliton microcombs provide a chip-based, octave-spanning source for self-referencing and optical metrology. We use a silicon nitride integrated photonics foundry to manufacture 280 single-chip solutions of octave-spanning microcombs on a wafer. By group

NIST Time and Frequency Bulletin

July 23, 2024
Author(s)
Kelsey Rodriguez
The Time and Frequency Bulletin provides information on performance of time scales and a variety of broadcasts (and related information) to users of the NIST services.

Fiber-coupled 2 mL vacuum-gap Fabry-Perot reference cavity for laser stabilization

May 25, 2024
Author(s)
Charles McLemore, Naijun Jin, Megan Kelleher, Yizhi Luo, Dahyeon Lee, Yifan Liu, Takuma Nakamura, David Mason, Peter Rakich, Scott Diddams, Franklyn Quinlan
Vacuum-gap Fabry-Perot cavities are indispensable tools for vastly improving the frequency stability of lasers, with applications across a diverse range of scientific and industrial pursuits. However, making these cavity-based laser stabilization systems

Dissemination of UTC(NIST) over 20 km of commercial optical fiber with active phase stabilization

May 2, 2024
Author(s)
Jacob VanArsdale, Matthew J. Deutch, Michael A. Lombardi, Glenn Nelson, Jeffrey Sherman, James Spicer, William Yates, Dylan Yost, Samuel Brewer
We demonstrate the transfer of a cesium frequency standard steered to UTC(NIST) over 20 km of dark telecom optical fiber. Our dissemination scheme uses an active stabilization technique with a phase-locked voltage-controlled oscillator. Out-of-loop

Tunable X-band opto-electronic synthesizer with ultralow phase noise

March 29, 2024
Author(s)
Igor Kudelin, Pedram Shirmohammadi, William Groman, Samin Hanifi, Megan Kelleher, Dahyeon Lee, Takuma Nakamura, Charles McLemore, Steven Bowers, Franklyn Quinlan, Scott Diddams
Microwave signals with low phase noise in the X-band (8-12 GHz) are essential for widespread technologies and important scientific developments. Photonic techniques, such as optical frequency division (OFD), leverage the high spectral purity of low-noise

Low-noise microwave generation with an air-gap optical reference cavity

January 30, 2024
Author(s)
Yifan Liu, Dahyeon Lee, Takuma Nakamura, Naijun Jin, Haotian Cheng, Megan Kelleher, Charles McLemore, Igor Kudelin, William Groman, Scott Diddams, Peter Rakich, Franklyn Quinlan
We demonstrate a high finesse, microfabricated mirror-based, air-gap cavity with volume less than 1 ml, constructed in an array, that can support low-noise microwave generation through optical frequency division. We use the air-gap cavity in conjunction

Visible to Ultraviolet Frequency Comb Generation in Lithium Niobate Nanophotonic Waveguides

January 15, 2024
Author(s)
Tsung Han Wu, Luis Ledezma, Connor Fredrick, Pooja Sekhar, Ryoto Sekine, Quishi Guo, Ryan Briggs, Alireza Marandi, Scott Diddams
The introduction of nonlinear nanophotonic devices to the field of optical frequency comb metrology has enabled new opportunities for low-power and chip-integrated clocks, high-precision frequency synthesis, and broad bandwidth spectroscopy. However, most

Threshold and Laser Conversion in Nanostructured-Resonator Parametric Oscillators

January 10, 2024
Author(s)
Haixin Liu, Grant Brodnik, Jizhao Zang, David Carlson, Jennifer Black, Scott Papp
We explore optical parametric oscillation (OPO) in nanophotonic resonators, enabling arbitrary, nonlinear phase matching and nearly lossless control of energy conversion. Such pristine OPO laser converters are determined by nonlinear light-matter

Kerr-induced synchronization of a cavity soliton to an optical reference

December 13, 2023
Author(s)
Gregory Moille, Jordan Stone, Michal J. Chojnacky, Curtis Menyuk, Kartik Srinivasan
The phase-coherent frequency division of a stabilized optical reference laser to the microwave domain is made possible by optical-frequency combs (OFCs). OFC-based clockworks lock one comb tooth to a reference laser, which probes a stable atomic transition

Statistics for quantifying aging in time transfer system delays

November 10, 2023
Author(s)
Tom Parker, Roger Brown, Jeffrey Sherman
The time delays in time transfer systems such as Two-Way Satellite Time and Frequency Transfer (TWSTFT), or GPS carrier phase (GPSCP) change over time. A double difference such as TWSTFT – GPSCP provides information on the changes in the relative time

Next-Generation Chip-Scale Atomic Clocks

October 16, 2023
Author(s)
John Kitching, Matthew Hummon, William McGehee, Ying-Ju Wang, Susan Schima
We describe work toward the development of next-generation chip-scale atomic clocks, which combine small size, low power consumption and manufacturability with high frequency stability. The use of optical transitions in microfabricated vapor cells improves

Quantum-limited optical time transfer for future geosynchronous links

June 21, 2023
Author(s)
Emily Caldwell, Jean-Daniel Deschenes, Jennifer Ellis, William C. Swann, Benjamin Stuhl, Hugo Bergeron, Nathan R. Newbury, Laura Sinclair
The combination of optical time transfer and optical clocks opens up the possibility of large-scale free-space networks that connect both ground-based optical clocks and future space-based optical clocks. Such networks promise better tests of general