Success Story: Quantum sensing for geodesy and environmental monitoring

© NASA VTAD/NASA Visible Earth/UF, S. Barke/AEI
The GRACE Follow-On satellite tracks intersatellite distance changes with unprecedented precision with its Laser Ranging Interferometer, allowing to study polar ice sheet decline and ground-water depletion processes.

QuantumFrontiers researchers from Leibniz University Hannover, PTB Braunschweig, Albert Einstein Institute and the Center Of Applied Space Technology And Microgravity (ZARM) in Bremen have made significant strides in the application of quantum sensors to geodesy and environmental metrology. Their combined work showcases the potential of quantum technologies to provide precise measurements for monitoring critical climate variables and enhancing our understanding of Earth’s dynamics. Simulations have demonstrated the potential benefits of terrestrial clock networks for height system unification and monitoring mass variations in regions such as Greenland or the Himalayas [1]. In space, these clocks can observe large-scale gravity variations [2].

Unique transportable instruments

QuantumFrontiers has enhanced the accessibility and robustness of quantum metrology, making precision measurements more widely available for critical applications in geodesy and environmental sensing. Transportable optical clocks have been pioneered by QuantumFrontiers researchers, now achieving unprecedented uncertainty levels (< 10–17). They have been used, e.g. in a recent campaign to determine the height difference between PTB Braunschweig and Max Planck Institute of Quantum Optics in Garching, separated by 940 km of fibre, with a record 24 cm uncertainty [3]. Complementing clocks, QuantumFrontiers researchers developed and optimised the unique transportable quantum gravimeter QG-1, based on an atom-chip BEC source for high-accuracy observations. QG-1 operated continuously for over a week and achieved accuracy of less than 10 nm/s2 [4, 5].

© Jan Hosan / LUH
Nina Heine working at the quantum gravimeter

Towards ubiqitous sensing

In interferometric inter-spacecraft ranging, QuantumFrontiers leveraged synergies with the LISA mission and developed an optical interferometer for the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) satellite mission [6]. They lead the instrument development [7] for the upcoming Mass-Change and Geosciences International Constellation (MAGIC) mission. This includes novel laser frequency determination schemes [8], a new optical head for multi-degree-of-freedom inertial sensing [9], and improved test mass sensing and accelerometry solutions [10]. GRACE-FO has been used to study the global hydrological cycle [11].

A notable extension of this collaborative success story towards environmental metrology is the expertise of J. Daniel Prades, who joined TU Braunschweig in 2024 as Alexander-von-Humboldt professor. He advances our activities in ubiquitous metrology by developing innovative sensor concepts, holding performance records in zero-power chemical sensors, miniaturised nano-heaters and microLEDs optimised for highly-localised irradiation [12–14].

This article is part of a series on QuantumFrontiers success stories

© Daniel Prades
Alexander von Humboldt Professor Daniel Prades

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