Researchers have discovered a new way to tune the quantum properties of tiny defects in diamond – by gently stretching or compressing the crystal. These findings could pave the way for next-generation sensors that can detect pressure, temperature, and other physical changes with unprecedented precision.
Defects in diamond, known as "color centers", are increasingly used in quantum technologies, including ultra-sensitive sensors and emerging quantum communication systems. Among them, the silicon-vacancy (SiV) center stands out for its exceptionally stable and bright light emission, making it a promising building block for quantum devices.
In this new study, an international research team led by scientists from the Singapore University of Technology and Design (SUTD) and Yangzhou University, China, investigated how these SiV centers respond when the surrounding diamond lattice is compressed or stretched. Using advanced computational modeling, the team systematically explored how the atomic structure and optical signals of the defect evolve under different mechanical conditions.
Their results reveal a surprisingly rich behavior. When the diamond is compressed, the defect remains stable and retains its original symmetry. But when stretched beyond a critical threshold – about 4% expansion – the defect undergoes a structural transformation, breaking its original symmetry and adopting a new configuration.
This transition is more than just a structural curiosity. It directly affects how the defect interacts with light. The researchers found that key optical signatures, including the color and intensity of emitted light, change in a smooth and predictable way as the material is strained.
Professor Yunliang Yue from Yangzhou University said: "These optical changes act like a built-in ruler. By simply measuring the light emitted from the defect, we can infer how much the material is being compressed or stretched."
Such behavior makes SiV centers highly attractive as nanoscale sensors. As the optical response varies continuously with deformation, these defects could be used to monitor pressure or strain with extremely high sensitivity—potentially at the level of individual nanostructures.
Beyond optical signals, the study also examined magnetic properties of the defect, which are important for techniques such as electron spin resonance. These properties were also found to change systematically with deformation, offering an additional sensing channel and further enhancing the versatility of the system.
Importantly, the research provides a microscopic understanding of why these changes occur. As the diamond lattice expands or contracts, the electronic structure of the defect is modified, which in turn alters how it interacts with light and magnetic fields. This insight helps bridge the gap between fundamental quantum physics and practical device applications.
The findings suggest that SiV centers could serve as robust and tunable platforms for quantum sensing technologies, especially in environments where mechanical deformation plays a role – such as high-pressure physics, nanoscale devices, or advanced materials systems.
"By showing how mechanical deformation can precisely control the quantum properties of silicon-vacancy centers, we open up new opportunities for designing multifunctional quantum sensors," said Assistant Professor and the Kwan Im Thong Hood Choo Temple Early Career Chair Professor Yee Sin Ang from SUTD. "This work provides both fundamental understanding and practical guidance for engineering quantum defects in real-world applications."
Dr Shibo Fang, SUTD Research Fellow, added, "What is particularly exciting is the predictability of the response. The defect behaves in a highly controllable way under strain, which is exactly what is required for reliable sensing technologies. Our study lays the groundwork for future experiments and device integration."
Looking ahead, the team believes that combining mechanical control with quantum defects could unlock new functionalities in quantum devices, including adaptive sensors and hybrid systems that respond dynamically to their environment.
