Two-dimensional materials have emerged as a promising platform for quantum annealing due to their unique electronic and spin properties. Among these materials, Ising spin glasses realized in 2D systems exhibit characteristics that could address some of the key challenges in quantum annealing, such as scalability and operating temperature constraints. Unlike bulk or three-dimensional systems, 2D materials offer atomic-scale thickness and reduced disorder, which can enhance coherence and controllability in quantum devices.

Quantum annealing relies on exploiting quantum fluctuations to find the ground state of a Hamiltonian, typically an Ising spin glass model, which represents complex optimization problems. D-Wave systems, the most prominent commercial quantum annealers, use superconducting qubits to implement these models. However, they face limitations in scalability due to the complexity of coupling thousands of qubits and the need for milli-Kelvin temperatures to maintain quantum coherence. Two-dimensional materials present an alternative pathway that may circumvent some of these challenges.

One of the primary advantages of 2D materials is their inherent scalability. The atomic thickness of materials like graphene, transition metal dichalcogenides (TMDCs), and hexagonal boron nitride (hBN) allows for dense integration of spin-based qubits. Recent studies have demonstrated that spin defects in 2D materials, such as vacancies in TMDCs, can serve as stable qubits with long coherence times even at elevated temperatures compared to superconducting systems. For example, certain spin defects in monolayer WSe2 exhibit coherence times exceeding microseconds at temperatures above 4 Kelvin, a significant improvement over superconducting qubits that require dilution refrigerators.

The reduced dimensionality of 2D materials also minimizes unwanted interactions that lead to decoherence in bulk systems. In three-dimensional spin glasses, disorder and phonon scattering degrade performance, but 2D systems can exhibit more controlled spin-spin interactions due to their restricted geometry. Theoretical models suggest that 2D Ising spin glasses can achieve better frustration management, a critical factor in quantum annealing, because interactions are more localized and tunable via external fields or strain engineering.

Temperature constraints remain a critical consideration. While superconducting qubits in D-Wave systems operate below 20 milli-Kelvin, 2D spin systems have shown potential for higher-temperature operation. Experiments on van der Waals magnets, such as CrI3, demonstrate that magnetic ordering persists up to 45 Kelvin, suggesting that engineered 2D spin glasses could function at significantly higher temperatures than superconducting counterparts. However, maintaining quantum coherence at these temperatures requires further optimization of material purity and defect engineering.

Another key distinction lies in the coupling mechanisms. D-Wave systems rely on programmable flux qubits with fixed nearest-neighbor coupling, which limits connectivity. In contrast, 2D materials enable tunable long-range interactions through electric or magnetic field gating. For instance, RKKY (Ruderman-Kittel-Kasuya-Yosida) interactions in graphene-based spin systems can mediate coupling over several nanometers, offering more flexible qubit connectivity. This adaptability could allow for more complex problem embedding in quantum annealing architectures.

Despite these advantages, challenges remain. Fabricating large-scale, defect-free 2D spin systems with uniform properties is nontrivial. Current synthesis techniques struggle to produce wafer-scale monolayers with the required spin homogeneity for reliable quantum annealing. Additionally, readout and control of individual spins in 2D materials demand advanced techniques such as nitrogen-vacancy (NV) center microscopy or spin-polarized scanning tunneling microscopy (STM), which are not yet scalable.

Comparatively, D-Wave systems benefit from mature fabrication and control infrastructure, whereas 2D material-based quantum annealers are still in early development. However, the potential for higher operating temperatures and enhanced scalability makes 2D materials a compelling avenue for future quantum annealing technologies. Research efforts are now focused on optimizing spin coherence times, improving material quality, and developing scalable readout methods to unlock their full potential.

In summary, 2D materials offer a promising alternative to conventional quantum annealing platforms by addressing scalability and temperature limitations. While D-Wave systems currently lead in practical implementations, the unique properties of 2D spin glasses could enable more versatile and higher-temperature quantum annealers in the future. Progress in material synthesis and spin control will be crucial to realizing these advantages.