This pioneering work realises a long-held aspiration of scientists: an MRI-like tool for quantum materials.
The team leveraged the Jülich group’s expertise in bottom-up single-molecule fabrication, conducting experiments at QNS with the Korean team’s advanced instrumentation and methodological expertise, to develop the world’s first quantum sensor for the atomic realm.
Given that the diameter of an atom is a million times smaller than the thickest human hair, visualising and precisely measuring physical quantities such as electric and magnetic fields emerging from atoms is extremely challenging. The observing tool must be highly sensitive and as small as the atoms themselves to sense such weak fields from a single atom.
A quantum sensor utilises quantum mechanical phenomena, such as electron spin or the entanglement of quantum states, for precise measurements. Over the past years, several types of quantum sensors have been developed. While many can sense electric and magnetic fields, it was previously believed that atomic-scale spatial resolution could not be achieved simultaneously.
The success of this new atomic-scale quantum sensor lies in the use of a single molecule. This represents a fundamentally different approach to sensing, as most other sensors rely on a defect in a crystal lattice. These defects develop their properties only when deeply embedded into the material, meaning they remain at a rather large distance from the object, preventing them from observing the object on the scale of single atoms.
The research team developed a tool that uses a single molecule to sense the electric and magnetic properties of atoms. The molecule is attached to the tip of a scanning tunnelling microscope and can be brought within a few atomic distances of the object.
"This quantum sensor is a game changer, because it provides images of materials as rich as an MRI and at the same time sets a new standard for spatial resolution in quantum sensors," said Dr. Taner Esat, lead author of the Jülich team. "This will allow us to explore and understand materials at their most fundamental level."
The long term collaboration hinged on Dr Esat, previously a post doc at QNS, who moved back to Jülich where he conceived this sensing molecule. He chose to return to QNS for a research stay in order to prove this technique using the center's cutting-edge instruments.
The sensor has an energy resolution that allows for detecting changes in magnetic and electric fields with a spatial resolution on the order of a tenth of an angstrom, where 1 angstrom typically corresponds to one atomic diameter. Moreover, the quantum sensor can be constructed and implemented in existing laboratories worldwide.
"What makes this achievement so striking is that we use an exquisitely engineered quantum object to resolve fundamental atomic properties from the bottom up. Preceding techniques for visualizing materials use large, bulky probes to try to analyze tiny atomic features," emphasised Dr. Dimitry Borodin, lead author, QNS. "You have to be small to see small."
This groundbreaking quantum sensor is poised to open up transformative avenues for engineering quantum materials and devices, designing new catalysts, and exploring the fundamental quantum behaviour of molecular systems, such as in biochemistry.
Highlighting the potential, Yujeong Bae, QNS’s Principal Investigator for the project, said: "The revolution in tools for observing and studying matter emerges from the accumulated basic science. As Richard Feynman said, 'There's plenty of room at the bottom,' the potential of technology for manipulating at the atomic level is infinite."
Professor Temirov, research group leader in Jülich, added: “It is exciting to see how our long-standing work in molecular manipulation has resulted in the construction of a record-holding quantum device.”
The research results were published in Nature Nanotechnology. The development of this atomic-scale quantum sensor marks a significant milestone in the field of quantum technology and is expected to have far-reaching implications across various scientific disciplines.
