In the first week of June, the European quantum gravimetry community gathered for a workshop at the GFZ. The goal was to collect strategic feedback on the activities of the major EU project EQUIP-G, which launched in 2025 and will help shape key future aspects of (terrestrial) gravimetry. More than 100 interested and relevant persons from EU policymaker to European companies and geophysical service providers and different communities (geodesy, quantum sensing, metrology, geosciences and defense) joined the event. It provided a floor for fruitful and intense discussions and exchange between all these key actors and interested people from the community.

Quantum gravimetry uses quantum technology for high-precision gravity measurements. EQUIP-G (European Quantum Infrastructure for Gravimetry) is a 4 year EU project founded on four main thematic pillars: (1) Quantum gravimeter procurement and testing, (2) Field deployments, (3) Data management and (4) Community building. The long-term goal: establish a permanent perennial entity of a shared park of quantum gravimeters in Europe. This will cover the terrestrial segment of the Pan-European quantum gravimetry infrastructure plan, declared by the EU commission, spanning from ground to space.

Quantum gravimetry as part of the EU Quantum Strategy

In general, quantum technologies are a declared key segment of Europe’s strategic development, expressed explicitly by the “Quantum Europe Strategy” which paves the road for the upcoming “EU Quantum Act” scheduled for adoption in 2026. This new EU Act has three main objectives: (1) boost research and innovation, (2) scale up industrial capacity and (3) reinforce supply chain resilience and governance.

Next to quantum computing, simulation and communication, quantum sensing is the most advanced of these areas.

Gravitational field measurement with quantum gravimeters

Measurements of gravity are a unique imaging tool that provides direct information about changes in mass on various spatial and temporal scales.

The operating principle is based on extremely cold, freely falling atomic clouds. These atomic clouds are attracted by Earth’s gravity and other masses. Using the principles of quantum technology, the atomic clouds are manipulated with laser beams in such a way that this gravitational force can be determined with high precision.

From an instrumental standpoint, quantum gravimeters possess highly advantageous properties that conventional gravimeters do not combine: (1) They can measure continuously, (2) they are designed for field measurements and under extreme conditions, (3) they are extremely user-friendly, so that operation does not require decades of experience, and (4) as absolute gravimeters, they are completely free of instrumental drift.

Relevance of quantum sensing for the geosciences

For the geosciences, this is particularly interesting and relevant in the following areas:

• hydrology (groundwater monitoring, resource mapping, process understanding)
• vulcanology (magma chamber monitoring, deformation tracking)
• oceanography (sea floor mapping)
• geothermal energy (reservoir mapping and quantification)
• geology (subsurface density mapping, fault detection)
• geodesy (reference systems, geoid determination)
• climate monitoring (mass redistribution monitoring)

Many of these fields are included in the 8 “use cases” which will be executing within EQUIP-G field deployments (2^nd project pillar).

Challenges in the field of quantum gravity

Although quantum gravimeters are well advances, compared to other quantum technologies, and reached a technology readiness level to be offered as a commercial product, there is still much research necessary to address existing challenges and persistent limitations. These span from instrument understanding and metrology (link to international reference systems and SI units), operator training and knowledge transfer across countries and stakeholders, implementation of FAIR data principles and the development of metadata standards for these instrument- and data-types, integration into large digital infrastructures (EPOS ERIC) to a resilient, active and dynamic community.

The EQUIP-G Workshop

Goal: to enable and support interest, acceptance and usage of this bleeding-edge technology by the community, which is the key pillar for a sustainable future. 

The EQUIP-G consortium does not want to work alone on these important topics and involve and include the entire community from the very beginning. 

With more than 100 participants, the event was a full success. A direct impact on upcoming activities across the entire community could already be observed, most prominent on numerous submitted proposals for the “open-call for instruments” where EQUIP-G provides project-external groups the opportunity to obtain a quantum gravimeter for their own research projects (more information on the project website).

Local workshop organization: GFZ, section 4.4 Hydrology (Marvin Reich)

Project website: https://www.equip-g.eu/

Workshop website: https://events.spacepole.be/event/268/