Researchers have successfully constructed a quantum battery within a quantum computer, marking an initial stride in assessing the potential of such devices to power emerging quantum technologies. Unlike conventional batteries, which store energy through electrochemical reactions, quantum batteries utilize quantum bits, or qubits. These qubits undergo alterations in their quantum states. While some studies suggest that leveraging quantum phenomena can lead to accelerated charging, the practical feasibility and overall utility of quantum batteries remain subjects of ongoing investigation.
Dian Tan from the Hefei National Laboratory in China highlighted the growing need for quantum counterparts to conventional batteries, stating, “Many future quantum technologies will require their quantum versions of batteries.” He further elaborated that despite considerable advancements in quantum computation, communication, and sensing, the energy storage mechanisms for these quantum systems have not been comprehensively explored.
Tan and his colleagues developed a battery employing 12 qubits constructed from minute superconducting circuits. Each qubit could be independently controlled via microwaves. In this setup, every qubit functioned as an individual battery cell and maintained interactions with its immediate neighbors. The researchers possessed the ability to regulate these interactions, which led them to experiment with two distinct charging protocols. One protocol mirrored the charging method of traditional, or classical, batteries and did not involve quantum interactions. The second protocol, conversely, actively utilized these quantum interactions.
The experimental findings indicated that employing quantum interactions among the qubits allowed the battery to achieve higher power levels on average and at a faster rate. Team member Alan Santos of the Spanish National Research Council noted, “The quantum battery achieves maximum power that is up to twice as large as the classical charging power.” He emphasized the significance of this result being achieved with each qubit interacting only with its nearest neighbor, as this aligns with standard configurations for superconducting quantum computers. Engineering more complex, advantageous interactions would present considerable engineering challenges.
James Quach, affiliated with the Commonwealth Scientific and Industrial Research Organisation in Australia, pointed out that previous quantum battery charging experiments often employed elements like molecules rather than being integrated into an existing quantum device. Quach and his collaborators had previously theorized the potential for quantum computers powered by quantum batteries to exhibit greater efficiency and be more amenable to scaling up, thereby enhancing their overall power. “This was a theoretical idea that we proposed only recently,” Quach commented, “but the new work could really be used as the basis to power future quantum computers.”
However, precise comparisons between conventional and quantum batteries present difficulties. Dominik Šafránek at Charles University in the Czech Republic expressed that there is currently no clear pathway to translate the measured advantages of quantum batteries into unambiguously functional devices. Kavan Modi from the Singapore University of Technology and Design added that for qubits interacting solely with their immediate neighbors, his team’s mathematical models indicate only modest charging advantages. These benefits, he cautioned, could be easily negated by inherent properties of real-world quantum computers, such as their susceptibility to noise or the limitations in qubit control speed.
Modi also suggested that as quantum computers may ultimately prove more energy-intensive than conventional ones, understanding energy transfer mechanisms within them could become essential for the development of very large-scale quantum computing systems. Tan sees the application of energy storage for quantum technologies, including quantum computers, as the most promising use case for his team’s quantum battery. The next phase of their research involves integrating their battery with a qubit-based quantum heat engine. This would enable the generation of energy, which could then be stored within the battery, all within the confines of a single quantum computer.