Skip to main content
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.

Phase-coherent detection of an optical dipole force by Doppler velocimetry



Michael J. Biercuk, Hermann Uys, Joseph W. Britton, Aaron Vandevender, John J. Bollinger


We report phase-coherent Doppler detection of optical dipole forces using large ion crystals in a Penning trap. The technique is based on laser Doppler velocimetry using a cycling transition in 9Be+ near 313 nm and the center-of-mass (COM) ion motional mode. The optical dipole force is tuned to excite the COM mode, and measurements of photon arrival times synchronized with the excitation potential show oscillations with a period commensurate with 2π/ωz. Experimental results compare well with a quantitative model for a driven harmonic oscillator. This technique permits detailed characterization of motional modes in complex ion crystals and provides frequency discrimination below the Fourier-limited linewidth of nearly degenerate modes. The preservation of oscillation phase information relative to the driving force is a key enabling capability, providing access to a new parameter that is typically discarded in time-averaged measurements.
Optics Express


Doppler velocimetry, ion trap, optical dipole force, Penning trap


Biercuk, M. , Uys, H. , Britton, J. , Vandevender, A. and Bollinger, J. (2011), Phase-coherent detection of an optical dipole force by Doppler velocimetry, Optics Express, [online], (Accessed April 20, 2024)
Created May 10, 2011, Updated February 19, 2017