Researchers from the Harish-Chandra Research Institute in India have recently explored the potential of quantum batteries designed using K-regular graphs, which are structures where each vertex has the same number of edges (K) connected to it. Their findings, published in the journal Physical Review Letters, shed light on the capabilities and limitations of these quantum batteries in terms of energy storage and extraction.
The team, consisting of Debkanta Ghosh, Tanoy Kanti Konar, Amit Kumar Pal, and Aditi Sen De, investigated how the regularity of the graph (the value of K) affects the battery’s performance. They discovered that a quantum battery based on a 0-regular graph, which essentially means no edges or connections, can store energy that scales linearly with the size of the system when charged using a K-regular graph. This linear scaling persists even when the charging process involves a collective K-regular charger with power-law decaying interactions.
However, the researchers found no evidence of superlinear scaling, which means the energy storage does not increase more than linearly with the system size. Instead, they observed that the work output, or the energy that can be extracted from the battery, improves systematically as the regularity (K) increases. This suggests that more connected graphs can lead to better performance in terms of energy extraction.
The study also introduced a new concept: the fraction of extractable work when only subsystems are accessible. The researchers found that this fraction remains independent of the system size if the battery is prepared in a specific quantum state known as the down-polarized product state. However, this independence breaks down when the battery is oriented along the x- and y-directions of the Bloch sphere, a representation used to describe the state of a two-level quantum system like a qubit.
While the findings do not indicate a quantum advantage in terms of superlinear scaling, they provide valuable insights into the design and performance of quantum batteries. For the energy industry, this research could contribute to the development of more efficient energy storage solutions, particularly in the realm of quantum technologies. As quantum batteries are still in the early stages of research, practical applications may be some time away, but understanding their fundamental properties is a crucial step towards future advancements.
The research was published in the journal Physical Review Letters, a prestigious peer-reviewed journal in the field of physics.
This article is based on research available at arXiv.