UKRI funds SEQUIN to probe Earth with a hybrid quantum array, on the path to sensing the cosmos

A major grant of £1.2 million from UK Research and Innovation (UKRI) is funding Sensing the Earth with a novel QUantum-classical INterferometer array (SEQUIN), an interdisciplinary collaboration between the Many-Body Quantum Dynamics Group at Cambridge’s Cavendish Laboratory, and the Department of Earth Sciences at the University of Oxford. The project brings together quantum sensing and seismic monitoring to improve the detection techniques of extremely faint signals from gravitational waves in space to deep vibrations within the Earth.

Gravitational waves have transformed how we understand the universe. These ripples in spacetime originate from the most dramatic events in the cosmos, such as colliding black holes, but they are very difficult to detect. Before colliding, black holes orbit each other, producing long lived gravitational waves that provide more information about their sources. Quantum sensors can measure these faint signals, but they can be masked by natural and human-made ground vibrations (seismic waves). Conversely, the Earth’s free oscillations are low-frequency vibrations that occur after the planet experiences a large-magnitude earthquake, characterised by natural resonant frequencies. These vibrations are sensitive to structures deep inside the Earth and are equally difficult to detect, even using large networks of seismometers.

The SEQUIN project will tackle both these challenges through a hybrid approach.

“Using real-time data from conventional seismometers alongside the ultra-sensitive capabilities of quantum sensors, we aim to filter out environmental noise and isolate signals with precision,” said Dr Jeremiah Mitchell, Cavendish Laboratory, University of Cambridge.

“Through integrating quantum sensors with seismic arrays, the real-time information from seismometers will make it possible to cancel out ground vibrations and develop a method for unmasking gravitational waves in future experiments, while quantum sensors will bring unprecedented sensitivity to long-period vibrations, ground motions with a repetition time of 100s – 1000s of seconds.”

“This opens the door not only to improved gravitational wave detection, but also to a deeper understanding of the Earth’s internal processes,” added Prof Mike Kendall of the Department of Earth Sciences, University of Oxford, who co-leads the research.

“The system will achieve far greater precision than either instrument could alone.”

“Bringing together physics, quantum technology and Earth science, this project will reveal a new way to explore both the cosmos and our planet, taking a major step forward in gravitational sensing and a powerful new tool for studying Earth’s deep interior and environmental processes,” concluded Prof Ulrich Schneider, who leads the Many-Body Quantum Dynamics Group at the Cavendish Laboratory, and co-leads this research from Cambridge.

The project is further strengthened by contributions from project partners, including the United States Geological Survey (USGS), UKRI-STFC Boulby Underground Laboratory, the University of Glasgow, and the Université de Strasbourg, who will provide expertise and specialised instrumentation, specifically precise and novel seismometers, to enhance the hybrid sensing network.

Researchers associated with the project

• Professor Ulrich Schneider, Cavendish Laboratory, University of Cambridge.
• Professor Mike Kendall, The Department of Earth Sciences, University of Oxford
• Dr Paula Koelemeijer, The Department of Earth Sciences, University of Oxford
• Dr Jeremiah Mitchell, Cavendish Laboratory, University of Cambridge
• Dr Tom Kettlety, The Department of Earth Sciences, University of Oxford

Image Description and Credit

Illustration of hybrid array disentangling seismic waves in the Earth and gravitational waves from outer space. Credit: Jeremiah Mitchell, (GoogleData SIO, NOAA, U.S. Navy, NGA, GEBCOLandsat / CopernicusIBCAOU.S. Geological Survey GeoBasis-DE/BKG (©2009) Inst. Geogr. Nacional)