Could Zinc Be the Next Breakthrough in Diamond Vacancy Complexes for Quantum Technologies?

On April 15, 2025, researchers Yihuang Xiong, Yizhi Zhu, Shay McBride, Sinéad M. Griffin, and Geoffroy Hautier published Identifying high performance spectrally-stable quantum defects in diamond, revealing that the Zn defect in diamond exhibits exceptional spectral stability and favorable electronic properties, making it a promising candidate for advancing quantum computing technologies.

Point defects in semiconductors are critical for technologies like spin qubits and photon networks. The nitrogen-vacancy (NV) center in diamond is widely used but suffers from spectral diffusion due to coupling with electric fields. Group IV vacancy complexes are more stable due to centrosymmetry but face challenges such as low operation temperatures, dark states, and difficulty in stabilizing charge states. Researchers systematically evaluated all possible vacancy complexes using high-throughput first-principles screening to find alternatives. They identified defects combining centrosymmetry, visible emission, favorable electronic structure, and defect levels within the band gap. Zinc (Zn) emerged as a particularly appealing candidate.

Quantum computing promises to solve complex problems beyond classical computers’ capabilities. Among various approaches, diamond-based quantum computing stands out for its use of defects, such as nitrogen-vacancy (NV) centers, to create qubits—quantum bits essential for computation.

Diamonds, known for their structural integrity, contain defects where a carbon atom is replaced by a nitrogen atom and an adjacent vacancy. These NV centers possess stable electron spins that maintain quantum states longer than many other materials, addressing the significant challenge of decoherence—where qubits lose their quantum state due to environmental interference.

A critical advancement involves precise control over the charge states and spin orientations within these defects. Researchers have developed methods to manipulate electrons’ charges and spins accurately, enabling reliable quantum operations. This control is fundamental for executing logic gates necessary for quantum computations, ensuring consistent task performance without errors.

To enhance scalability and efficiency, researchers employ finite-element modeling—a numerical technique traditionally used in engineering. By applying this method, they optimize device structures, leading to more efficient integration into practical applications. This approach helps design systems that can handle larger computations while maintaining stability.

Despite these advancements, challenges remain. Phonons—quantized vibrations within the crystal lattice—affect qubit lifetimes by causing decoherence. Researchers are actively exploring ways to minimize phonon interactions, aiming to extend the duration qubits maintain their states without errors. This work is crucial for improving reliability and performance.

Overcoming these challenges could lead to practical applications in cryptography, drug discovery, and optimization problems. By addressing decoherence and enhancing qubit control, researchers pave the way for quantum computers moving beyond theoretical potential into real-world utility.

Diamond-based quantum computing represents a significant step forward in overcoming key challenges. Through advancements in defect utilization, charge state control, device optimization, and addressing phonon interactions, researchers are laying the groundwork for more reliable and scalable quantum systems. These efforts bring us closer to realizing the transformative potential of quantum computing in solving complex, real-world problems.