A team of researchers have achieved a major breakthrough in the field of quantum physics with the first experimental observation of Dirac exceptional points (EPs). Under the leadership of Yang Wu and his dedicated team, this success deserves to be a national blueprint. On April 27, 2025, they published their findings in Physical Review Letters. In this, the researchers added an important new component to the rapidly growing understanding of non-Hermitian systems, which are central to the development of next-generation quantum technologies.
Dirac exceptional points are special types of energy-level degeneracies that happen in non-Hermitian systems. In contrast to other typical exceptional points, such as a genuine EP, Dirac EPs exhibit a local real-valued energy spectrum around it, accompanied by eigenstate degeneracy. This observation may have deep implications for the green photonic manufacturing of next-generation quantum devices.
The Research Team and Their Methodology
Out of the team, senior author Xing Rong led the research team to use nitrogen-vacancy defects in diamond as their experimental platform. These atomic-scale quantum systems allowed them to build and observe Dirac exceptional points with remarkable precision.
The researchers applied this methodology to investigate the interplay of various properties of Dirac EPs in a laboratory. This method gave them a rich and deep understanding of how these properties operate.
“We engineered a non-Hermitian Hamiltonian hosting Dirac EPs by introducing a spin-squared operator term (Sz²) into a three-level non-Hermitian system,” – Xing Rong.
This successful observation of Dirac EPs marks a fantastic new frontier for quantum physicists and engineers to explore. The discoveries have potential application to greatly improve control of all key technologies including quantum sensors and quantum computers.
Implications for Quantum Technologies
This major leap forward not only unlocks new avenues for commercial use, but questions long-held paradigms of quantum science.
The implications of this discovery will hopefully inspire more experimental work in the field of non-Hermitian dynamics and quantum control protocols. To date, experimental physicists had seen just two varieties of exceptional points. These ideas were originally suggested more than a hundred years ago. The sense that Dirac EPs are an emergent phenomenon would generate further investigation and experimentation within the field.
“Through Dirac EPs, non-adiabatic transitions associated with typical EPs can be avoided, which will make the experimental investigation of complex geometric phases possible.” – Xing Rong.
The team’s results show that there’s promising opportunity. Those studies have the potential to reveal something profound about the quantum world and expand the space for what future quantum technology could be.
Future Research Directions
The discovery may inspire further experimental work in the field of non-Hermitian dynamics and quantum control protocols. Historically, physicists have only been able to observe two types of exceptional points since their existence was first proposed over a century ago. The introduction of Dirac EPs could spur additional research and exploration in this area.
Rong summed up the significance of their work:
“Thus, the successful observation of Dirac EP in our work paves the way toward the experimental study of geometric phase in non-Hermitian systems.” – Xing Rong.
The team’s findings suggest that further studies may yield new insights into quantum behavior and expand the horizons for future quantum technologies.