Researchers Tian-Yi Gu and Gaoyong Sun from the University of Science and Technology of China have extended the application of Lee-Yang theory, a framework used to understand phase transitions in various systems. Their work, published in Physical Review Letters, introduces new concepts to characterize quantum phase transitions, which could have implications for understanding and manipulating quantum systems in energy technologies.
Lee-Yang theory provides a way to analyze phase transitions by examining the partition function, a key concept in statistical mechanics. The researchers have expanded this theory to include non-Hermitian symmetry breaking and fidelity zeros, which are points where the quantum state loses its coherence. They applied this extended theory to several quantum models, including the XY, XXZ, XYZ, and the Z3 clock model, all subjected to a complex external magnetic field.
In the XY, XXZ, and XYZ models, the complex field breaks parity symmetry, leading to oscillations in the ground state between two parity sectors. This results in fidelity zeros within the ordered phases of these models. For the Z3 clock model, the complex field splits the real part of the ground-state energy between the neutral sector and the charged sectors, while maintaining the degeneracy within the charged sector. Fidelity zeros in this model only appear after projecting out one of the charged sectors, and the scaling of these zeros aligns with analytical predictions.
The practical applications of this research for the energy sector could be significant. Understanding quantum phase transitions can aid in the development of quantum technologies, such as quantum sensors and quantum computers, which could revolutionize energy systems. For instance, quantum sensors could enhance the efficiency of energy grids by providing real-time, high-precision monitoring. Quantum computers, on the other hand, could optimize complex energy distribution networks and accelerate the discovery of new materials for energy storage and conversion. The extended Lee-Yang theory provides a powerful tool for exploring these possibilities.
This article is based on research available at arXiv.