Researchers have developed a strain engineering system to control how quantum defects behave and enhance spin readout contrast in quantum systems.
Quantum defects are tiny imperfections in solid crystal lattices that can trap individual electrons and their spin. These defects are central to the functioning of various quantum technologies, including quantum sensors, computers and communication systems.
Reliably predicting and controlling the behaviour of quantum defects is therefore crucial, as it could pave the way for the development of better-performing quantum systems tailored for specific applications.
The new development could open new possibilities for the realisation of sophisticated quantum biosensing devices and other advanced quantum technologies.
The relationship between spin readout and quantum defects
“Our paper was inspired by the challenge of achieving reliable spin readout in solid-state quantum defect systems, especially at room temperature,” the authors stated.
“We aimed to show that strain could be a potential control parameter to significantly enhance the readout contrast of high-spin solid-state defects, which is crucial for advancing quantum technologies, such as developing efficient quantum sensors operating under ambient conditions.”
As a first step, they developed a framework that describes the relationship between a system’s spin readout contrast and the electronic structure of high-spin defects.
Professor Adam Gali from HUN-REN Wigner Research Center, who led the research, explained: “We hypothesised that specific strain fields can tune these quantities, thereby enabling control over the readout contrast. Building on our previous theoretical work, we tested this hypothesis and found a significant strain-induced effect.”
The potential of strain engineering for controlling spin readout
Building on the theoretical work by Gali and his colleagues, another research group led by Professor Qinghai Song at Harbin Institute of Technology performed experiments aimed at assessing the potential of strain engineering for controlling spin readout contrast.
As part of these experiments, the team used the existing strain within silicon carbide membranes and measured the spin properties of individual quantum defects.
“Our experiments confirmed the simulations, demonstrating a significantly enhanced readout contrast, which means we can distinguish between different spin states more effectively,” Song commented.
“The most significant finding is that strain engineering is a powerful and practical way to boost the spin readout contrast of quantum defects, achieving over 60% at room temperature.”
This work by Gali, Song and their colleagues demonstrates that the careful engineering of the strain applied to quantum systems can significantly improve the ability to distinguish between distinct spin states within them.
As part of their study, the researchers showed that strain engineering can significantly enhance the sensitivity of quantum sensors.
Improving the approach for other quantum devices
Other research teams could soon draw inspiration from this paper and set out to devise other strain engineering-based strategies to control quantum defects precisely.
The researchers plan to continue improving their approach and assess its potential for enhancing the performance of other quantum devices.
Song concluded: “Our future plans include seeking more precise methods for controlling strain and achieving a more accurate characterisation of the underlying physics of strain-spin interactions.
“We also aim to extend strain engineering to other quantum defect systems and integrate these strained materials into advanced quantum circuits.”