We present an ultrastable microwave system devoted to synthesizing photonic microwave signals in the RF, L-, S-, and X-bands. The rack-mounted system shows fractional stability below 10 -14 level from 100 ms up to 10 hours of operation on a 10 GHz signal, also allowing synchronization with optical clocks.

We report on a transportable and easy-to-operate optical clock utilizing the 2S1/2 - 2D3/2 transition of a single trapped 171Yb+ ion at 436 nm. Developed within a pilot project for quantum technology in Germany lead by industry, the clock is set up in two 19″ racks. In this way, transportation can easily be realized, and the large degree of automatization allows for operation outside highly specialized laboratories for applications beyond basic research. Comparisons to existing high-accuracy optical clock systems enable a verification of the clock's stability and uncertainty budget at the low 10−17 level. During these tests, operation with 99.8% availability over more than 14 days has been achieved.

The advent of long-term stable ultra-low noise (ULN) frequency combs opens new prospects for precision measurements. We characterize the stability of such ULN combs and present dual-comb precision spectroscopy of molecules and cavities.

We present the progress towards a transportable photonic microwave synthesizer, porting ultra-high optical stability to a 12 GHz signal. The system is composed of two main sub-units: a 194 THz transportable ultra-stable laser with sub-Hz linewidth and an ultra-low noise optical frequency comb used for dividing such optical frequency to the microwave domain. Characterizing the signal by means of a self-made cross-correlator, a phase noise power spectral density of -170 dBc/Hz at 10 kHz Fourier frequency is measured. This result surpasses the performance demonstrated with transportable Cryogenic Sapphire Oscillator.