Researchers P. G. Pritchard and James M. Rondinelli from Northwestern University have developed a new theoretical framework to better understand and model certain types of defects in materials used for superconducting qubits. Their work, published in the journal Physical Review B, focuses on two-level systems (TLS) and their interactions with the surrounding lattice structure, which can significantly impact the performance of quantum computing devices.
Superconducting qubits, the building blocks of quantum computers, rely on materials that can maintain quantum coherence for extended periods. However, defects in these materials, such as two-level systems, can cause decoherence and limit the qubits’ performance. Pritchard and Rondinelli’s research aims to provide a more accurate model of these TLS to help engineers design better materials and mitigate their effects.
The researchers introduced a lattice-renormalized formalism that improves upon previous models by incorporating composite phonon coordinates. These coordinates help capture the distortions in the crystal lattice that occur when atoms tunnel between two potential energy states. By doing so, the new model can more accurately compute tunnel splittings and excitation spectra, which are crucial for understanding TLS dynamics.
One of the key findings of this study is the strong anharmonic couplings between tunneling atoms and lattice phonons. This means that the interactions between these entities are not linear and can significantly affect the overall behavior of the system. By establishing a direct link between TLS dynamics and phonon-mediated strain interactions, the researchers provide valuable insights into defect-induced decoherence in superconducting qubits.
Moreover, the new formalism can be generalized to multi-level systems (MLS), which are more complex versions of TLS. This extension allows for a better understanding of various defects and their impact on qubit performance. The researchers hope that their work will guide strategies for materials design, ultimately leading to the development of superconducting qubits with reduced TLS-related loss and improved coherence times.
In summary, Pritchard and Rondinelli’s research presents a significant advancement in modeling TLS and their interactions with the lattice structure. By providing a more accurate and comprehensive framework, their work paves the way for better materials design and improved performance of superconducting qubits in the energy sector and beyond. The research was published in Physical Review B, a peer-reviewed journal dedicated to the publication of original research in all areas of condensed matter and materials physics.
This article is based on research available at arXiv.