Th. Udem

TL;DR: The generation of intense, few-cycle laser pulses with a stable carrier envelope phase that permit the triggering and steering of microscopic motion with an ultimate precision limited only by quantum mechanical uncertainty are reported.

TL;DR: The frequency comb generated by a femtosecond mode-locked laser is used and broadened to more than an optical octave in a photonic crystal fiber to realize a frequency chain that links a 10 MHz radio frequency reference phase-coherently in one step to the optical region.

TL;DR: In this article, the authors measured the absolute optical frequency of the cesium line at 335 THz (895 nm) and compared it with the fourth harmonic of a He-Ne laser at 88.4 THz.

TL;DR: An all-optical atomic clock referenced to the 1.064-petahertz transition of a single trapped199Hg+ ion is demonstrated and an upper limit for the fractional frequency instability of 7 × 10−15 is measured in 1 second of averaging—a value substantially better than that of the world's best microwave atomic clocks.

TL;DR: An absolute frequency measurement of the hydrogen 1S-2S two-photon transition in a cold atomic beam with an accuracy of 1.8 parts in 10(14) Hz is reported on.