Superabsorption Progress Towards Quantum Batteries

University of Adelaide and their overseas partners have successfully proved the concept of superabsorption, a crucial idea underpinning quantum batteries.

Quantum batteries offer the potential for vastly better thermodynamic efficiency, and ultra-fast charging time, much faster and more efficient than the electrochemical batteries like Nickel Metal Hydride or Lithium Ion, in common use today. By expanding earlier theoretical research into individual, isolated quantum batteries to consider a more realistic, many-body system with intrinsic interactions, the researchers have shown that interacting many-body quantum batteries do charge faster than their non-interacting counterparts.

The bigger the number of quantum batteries, the less time they need to charge. If one quantum battery charge takes an hour, two batteries would take 30 minutes. Increasing the number of quantum batteries to 10,000 and they would pretty much charge instantaneously.

To prove the concept of superabsorption, they built several wafer-like microcavities of different sizes which contained different numbers of organic molecules. Each was charged using a laser.

The idea of the quantum battery has the potential to significantly impact energy capture and storage in renewable energy and in miniature electronic devices.

Science Advances – Superabsorption in an organic microcavity: Toward a quantum battery

The rate at which matter emits or absorbs light can be modified by its environment, as markedly exemplified by the widely studied phenomenon of superradiance. The reverse process, superabsorption, is harder to demonstrate because of the challenges of probing ultrafast processes and has only been seen for small numbers of atoms. Its central idea—superextensive scaling of absorption, meaning larger systems absorb faster—is also the key idea underpinning quantum batteries. Here, we implement experimentally a paradigmatic model of a quantum battery, constructed of a microcavity enclosing a molecular dye. Ultrafast optical spectroscopy allows us to observe charging dynamics at femtosecond resolution to demonstrate superextensive charging rates and storage capacity, in agreement with our theoretical modeling. We find that decoherence plays an important role in stabilizing energy storage. Our work opens future opportunities for harnessing collective effects in light-matter coupling for nanoscale energy capture, storage, and transport technologies.

Other Quantum Battery Research

Arxiv – Quantum batteries at the verge of a phase transition

Starting from the observation that the reduced state of a system strongly coupled to a bath is, in general, an athermal state, we introduce and study a cyclic battery-charger quantum device that is in thermal equilibrium, or in a ground state, during the charge storing stage. The cycle has four stages: the equilibrium storage stage is interrupted by disconnecting the battery from the charger, then work is extracted from the battery, and then the battery is reconnected with the charger; finally, the system is brought back to equilibrium. At no point during the cycle are the battery-charger correlations artificially erased. We study the case where the battery and charger together comprise a spin-1/2 Ising chain, and show that the main figures of merit – the extracted energy and the thermodynamic efficiency – can be enhanced by operating the cycle close to the quantum phase transition point. When the battery is just a single spin, we find that the output work and efficiency show a scaling behavior at criticality and derive the corresponding critical exponents. Due to always present correlations between the battery and the charger, operations that are equivalent from the perspective of the battery can entail different energetic costs for switching the battery-charger coupling. This happens only when the coupling term does not commute with the battery’s bare Hamiltonian, and we use this purely quantum leverage to further optimize the performance of the device.

SOURCES- University of Adelaide, Science Advances, Arxiv
Written By Brian Wang,