The quest for scalable, high-performance quantum computing has led researchers to explore novel material systems that can host stable and controllable quantum bits (qubits). Among these, two-dimensional (2D) materials—such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs)—have emerged as promising candidates due to their unique electronic, optical, and mechanical properties. A critical avenue for optimizing qubit performance in these materials is atomic precision defect engineering, where defects are deliberately introduced and manipulated at the single-atom level to create and control quantum states.
Defects in crystalline materials have traditionally been viewed as undesirable imperfections that degrade performance. However, in the context of quantum computing, certain defects—such as vacancies, dopants, and grain boundaries—can serve as localized quantum emitters or spin centers that function as qubits. The challenge lies in engineering these defects with atomic precision to maximize coherence times, controllability, and scalability.
The ability to manipulate defects with atomic precision is crucial for tailoring qubit properties. Several advanced techniques have been developed to achieve this:
Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) allow researchers to image and manipulate individual atoms and defects. For example, STM can be used to remove or deposit single atoms with sub-nanometer precision.
FIB systems, often using gallium ions, can selectively sputter atoms from a 2D material to create vacancies or pattern defect arrays.
Targeted chemical reactions can modify specific atomic sites. For instance, hydrogenation of graphene can introduce defects that alter its electronic structure.
High-energy electron beams in transmission electron microscopes (TEM) can knock out atoms, creating vacancies with precise control over defect density.
Certain defects in 2D materials exhibit quantum states that can be harnessed as qubits. Below are some of the most studied systems:
Analogous to NV centers in diamond, nitrogen-vacancy centers in hBN have shown promise as optically addressable spin qubits. Their room-temperature operation and integration with photonic structures make them attractive for quantum networks.
Silicon substitutional defects in graphene can introduce localized mid-gap states that serve as spin qubits with long coherence times.
Defects in TMDs like MoS2 can host single-photon emitters, which are useful for quantum communication.
Despite progress, several challenges remain in utilizing defects for scalable quantum computing:
The field is rapidly evolving with several exciting directions:
AI-driven simulations can predict optimal defect configurations for desired qubit properties, accelerating material discovery.
Combining different types of defects (e.g., vacancies coupled with dopants) may enable more complex quantum operations.
New methods such as directed self-assembly or templated growth could enable mass production of defect-engineered 2D materials.
Atomic precision defect engineering in 2D materials represents a powerful strategy for developing high-performance qubits. By leveraging advanced fabrication techniques and deepening our understanding of defect physics, researchers are paving the way toward practical quantum computing technologies. Continued innovation in this field will be essential to overcome existing challenges and unlock the full potential of 2D materials for quantum applications.