Researchers from the University of Chicago’s Pritzker School of Molecular Engineering, Argonne National Laboratory, and the University of Modena and Reggio Emilia have unveiled a cutting-edge computational tool. This tool, integrated into the open-source software package WEST within the Midwest Integrated Center for Computational Materials (MICCoM), is a brainchild of Prof. Marco Govoni’s team. The innovation addresses the behavior of atoms within quantum materials when exposed to light, significantly advancing the understanding and engineering of materials for quantum technologies.
Prof. Marco Govoni, leading the project, expressed the tool’s significance in broadening scientists’ capabilities to explore quantum materials. The tool, WEST-TDDFT (Without Empty States—Time-Dependent Density Functional Theory), showcased its accuracy in studying semiconductor-based materials. The findings, published in the Journal of Chemical Theory and Computation, emphasize the tool’s potential to delve into systems and properties previously inaccessible on a large scale.
Giulia Galli, Liew Family Professor of Molecular Engineering and senior author of the paper, highlighted the groundbreaking aspect of their work. The tool facilitates the study of materials for quantum technologies, unlocking possibilities that were challenging to explore in the past. The group’s research demonstrated the tool’s precision across three different semiconductor-based materials, affirming its applicability to a broad spectrum of related materials. Importantly, the developed software is designed to operate efficiently on multiple high-performance architectures, ensuring scalability in computational studies.
The building blocks of quantum information
Qubits, the foundational units of information driving the potential of quantum technologies, distinguish themselves from classical bits by existing in states of superposition—simultaneously embodying 0 and 1. These quantum bits leverage minuscule defects within materials, like anomalies in crystal lattices, to function as qubits. These defects, known as “point defects,” exhibit sensitivity to their surroundings’ electric, optical, and magnetic properties, endowing them with sensor capabilities.
Researchers harness these point defects to understand their interaction with photons, enabling insights into energy state changes. This comprehension is pivotal for manipulating qubits or designing materials that utilize them as sensors or data storage units. Giulia Galli emphasized the significance of unraveling how these materials absorb and emit light, stating, “Light is how you interrogate these materials.”
While researchers could previously predict light absorption and emission by point defects, delving into atomic processes during the material’s excited state posed challenges, especially for large and complex systems. The development of a deeper understanding in this realm is poised to enhance the manipulation and design of materials crucial for advancing quantum applications.
Streamlining complex calculations
Solving the intricate quantum mechanical equations determining atomic properties demands substantial computing power. In a groundbreaking effort, Giulia Galli’s team introduced a more efficient method of solving these equations without compromising accuracy.
This advancement enables faster and more efficient analysis, making it feasible to apply these equations to larger systems. Previously, the computational demands made it impractical to analyze such systems. Graduate student Yu Jin, the first author of the study, highlighted the significance, stating, “With these methods, we can study the interaction of light with materials in systems that are quite large, meaning that these systems are closer to the experimental systems actually being used in the laboratory.”
The team’s innovative approach is versatile, running seamlessly on both central processing units (CPUs) and graphics processing units (GPUs). They successfully applied this method to explore the excited state properties of point defects in materials like diamond, 4H silicon carbide, and magnesium oxide. Remarkably, the tool demonstrated its effectiveness in calculating properties even for systems with hundreds or thousands of atoms. This breakthrough opens the door to more practical and expansive applications of quantum research in real-world experimental settings.
A broader goal
Within the MICCoM team, comprised of Dr. Victor Yu, Yu Jin, and Prof. Marco Govoni, ongoing efforts focus on refining algorithms within the WEST package, notably the efficient WEST-TDDFT, to study diverse material classes. Beyond the realm of quantum technologies, their applications extend to low power and energy applications.
Prof. Marco Govoni emphasized their achievement in enhancing the efficiency of equations describing light emission and absorption for practical systems. He stated, “We’ve found a way to solve the equations describing light emission and absorption more efficiently so that they can be applicable to realistic systems,” highlighting the method’s dual prowess in efficiency and accuracy.
This novel tool aligns seamlessly with the broader objectives of the Galli lab, dedicated to studying and designing new quantum materials. In a recent publication, the team delved into the behavior of spin defects near a material’s surface, revealing distinctions based on surface termination. These findings carry implications for the design of quantum sensors relying on spin defects.
Moreover, their research extends to the properties of ferroelectric materials utilized in neuromorphic computing, as evidenced by a recent paper in npj Computational Materials. This multifaceted research underscores the team’s commitment to advancing not only quantum technologies but also contributing insights to varied domains, from materials science to computing.
Source: University of Chicago