In the first 18 months of the project, project partners engaged in a number of key communication and dissemination activities.  8 presentations and 3 invited oral presentations were given, and 6 posters were presented at conferences such as Integrated Optics - Sensors, Sensing Structures and Methods (IOS 2022), IEEE EFTF-IFCS 2022, the International Symposium on Novel Materials and Quantum Technologies (ISNTT 2021), the 8th Congress of the French Optical Society (OPTIQUE Dijon 2021), and the 760. WE-Heraeus-Seminar. Five training courses were delivered, two at universities, one at an international conference on subjects pertaining to the development and applications of ultrastable lasers.  A dedicated project website was set up to communicate information on the project to a broader audience and serve as a platform for information and document exchange. The website is accessible at www.ptb.de/empir2021/nextlasers/home/.

Impact on industrial and other user communities

This project will open the path for the next generation improved laser oscillators that – with the help of femtosecond combs – can provide ultrastable frequencies from radio frequency up to the visible and UV spectral region. These techniques can be transferred to companies that feed the supply chain for science and application and improved measurement capabilities, e.g., in the fields of optical telecommunication, radar systems, long distance fibre links, synchronisation of telecommunication networks, satellite navigation and communication systems, and optical sensing. Also, all quantum technologies that are limited by decoherence effects from their local oscillators, e.g., in quantum simulation, quantum computing or coherent quantum-communication, will benefit from improved and readily available ultrastable oscillator. Interest from industry has appeared on taking up the developments on ultrastable laser, especially concerning continuous closed cycle cooling (objective 3) and converting them into commercial products.
The observation of so far unexpected noise in AlGaAs coatings has attracted much attention from the gravitational wave community, leading to an invitation to a workshop organized by LIGO on mirrors for the next generation of gravitational wave detectors.

Impact on the metrology and scientific communities

The instability of the interrogation laser is one of the main limitations for the stability of optical clocks, which in turn limits their efficient evaluation and corresponding improvement, because excessive averaging times are required to detect small frequency shifts. Therefore, the novel ultrastable laser sources at the required wavelength for optical clocks from this project will immediately improve both the stability and the accuracy of all current optical clocks. This will improve timekeeping, accelerate a redefinition of the second and enable applications of optical clocks for geodesy, where 10^-18 relativistic frequency shifts need to be resolved to achieve a 1 cm height resolution. Reliable ultrastable lasers as flywheels with instability below that of currently employed masers can bridge downtimes of optical clocks, and thus contribute to an improved realisation of International Atomic Time (TAI) by optical standards.
The European comparison campaigns of optical clocks within the EMPIR project ROCIT “Robust optical clocks for international timescales” benefitted already from improved ultrastable lasers. E.g. the Yb+ ion clock and the Sr lattice clock at PTB that were participating in the ROCIT comparisons, could increase their interrogation time and thus improve the stability and reliability by using an ultrastable reference laser pre-stabilized to a cryogenic Si cavity that is investigated in NEXTLASERS. Similarly, in the Yb lattice clock at INRIM link could benefit from improved cavity stability (see publication Clivati et al,, 2022).
Concerning the future change in the definition and realisation of the SI unit of time, the route to impact will be through the EURAMET Technical Committee on Time and Frequency. The consortium is well represented in this body, where information on the project progress and outputs will be disseminated through tailored presentations and written reports.
The highest resolution in radio-astronomical observations is achieved using Very Long Baseline Interferometry (VLBI). Significant improvements of the VLBI performance at mm wavelengths can be expected by replacing H-masers with more stable lasers developed in this project. Providing better frequency and timing stability to e.g. VLBI geodetic observatories (“core station”) of the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) will enable the identification and removal of systematic measurement biases for co-located geodetic instrumentation and calibration of space geodetic measurements. Improved VLBI is also of interest to the Time and Frequency metrology community, as it is used to monitor the rotation of the Earth with respect to TAI.

Impact on relevant standards

As a project is addressing fundamental aspects, no immediate impact on standards beyond the early-stage interaction with metrology bodies is expected.

Longer-term economic, social and environmental impacts

Europe has a long tradition of excellence in quantum research and retaining its globally strong position in this field is of great strategic importance. In the EU “Quantum Manifesto” laser sources were identified as fundamental to building quantum devices, as well as to numerous spin-off applications. The ESA Quantum Technologies in Space strategic report defines ultrastable lasers as one of the main enabling tools for such goals as Time and Frequency Services, Earth Sensing and Observation, and Fundamental Physics. The next generation of ultrastable lasers that will be developed in this project will support this target.
Furthermore, quantum sensors for monitoring the environment in Earth sensing and observation can be improved or made suitable for practical use in the first place using readily available ultrastable frequency sources. Lastly, quantum devices relying on ultrastable sources can impact society by improving telecommunication, navigation, quantum cryptography and quantum computing.
Long-term impact on the multi-billion wireless telecommunication market from improved ultrastable sources is also expected. Mobile telecommunications will require synchronised clocks at every physical layer and currently sub-ns synchronisation is envisioned for the highest layer of clocks. Even higher performance at the 10 ps level will be required for monitoring the performance of the highest production level. Ultrastable lasers in combination with frequency combs as optical frequency dividers can provide superior RF-signals for monitoring the performance and correct operation of even the highest level of accuracy.
The annual market revenues in Global Navigation Satellite Systems from both devices and services are expected to grow to €325 billion in 2029. The European GNSS industry accounts for more than a quarter of the global market share. However, there is a growing concern about the over-reliance of critical infrastructure since GNSS radio signals are greatly affected by the weather, unencrypted, and easily jammed, and no back up system is available. With the ability to provide superior RF-signals using ultrastable lasers located at ground stations of the GNSS, it will be possible to monitor GNSS functionality and to detect jamming attempts of this critical infrastructure.
At the current stage of the project, contacts to industry have been established to transfer the newly developed technology to commercially available devices.