A recent study in PRX Quantum from the University of Oulu identifies key limits on quantum battery reliability and shows how different charging protocols can balance high power output with steady, predictable energy and power delivery. The findings help clarify what “dependable” performance will require in practice, bringing usable quantum energy-storage systems a step closer.
Quantum uncertainty imposes a fundamental trade-off in quantum batteries, limiting their ability to deliver steady power and reliable energy simultaneously.
Quantum batteries are an emerging area of research, with progress coming from theoretical work and early proof-of-concept experiments in small quantum systems. Unlike the chemical batteries used in everyday devices, quantum batteries store and transfer energy using quantum states.
Researchers are exploring them as potential power sources for quantum processors and other quantum technologies. Much of the early work has focused on how quickly and efficiently these batteries can be charged.
In their recent study, the team identified fundamental limits on fluctuations in both the energy a quantum battery delivers and the rate at which it supplies that energy.
A quantum battery ideally should not only be fast and powerful but also needs to charge or deliver energy in a reliable and stable manner at the same time. Our work shows that quantum mechanics places fundamental limits on the reliabilities of quantum batteries.
Brij Mohan, Study First Author and Postdoctoral Researcher, University of Oulu
The researchers show that a familiar cornerstone of quantum mechanics, the uncertainty relation, prevents energy fluctuations and power variations from being minimized at the same time. In other words, a quantum battery cannot be tuned to deliver both highly reliable energy transfer and perfectly steady power at the same time.
Here, “stability” and “reliability” mean keeping fluctuations small relative to their average values. The trade-off arises because, in closed quantum batteries, work and power are represented by non-commuting operators, much like position and momentum in standard quantum mechanics.
The team then examined how this trade-off relates to methods for charging multiple quantum battery cells. In parallel charging, the cells function autonomously. Collective charging involves all cells simultaneously. Hybrid charging represents a midpoint between these two approaches, in which groups of cells interact during the charging process.
The findings indicate that more robust collective charging increases power but also amplifies power fluctuations, which reduces power reliability. This suggests that evaluating quantum-battery performance based solely on maximum power is inadequate.
Our results show that there is a meaningful way to balance power enhancement and the reliability of work and power. Intermediate-range interactions based charging scheme can provide a useful compromise between high power and stable operation.
Tanmoy Pandit, Research Scientist, VTT Technical Research Centre of Finland
The researchers further investigated quantum batteries with transverse Ising-type many-body interactions and found a similar qualitative trade-off between power and reliability. This finding suggests that the phenomenon is not limited to the most basic theoretical framework.
The reliability limits connect quantum fluctuations with many-body quantum physics in a direct way. They provide useful charging strategies that are practically advantageous.
Manabendra Nath Bera, IISER Mohali
“Quantum batteries offer a fascinating link between quantum information, thermodynamics, and many-body physics. Understanding their fluctuations is essential if these systems are eventually to become useful technological resources,” added Maciej Lewenstein, ICFO, Spain.
The researchers' next goal is to explore the limits of reliability in more practical environments, accounting for factors such as noise, energy loss, open-system behavior, and experimentally relevant quantum platforms.
Quantum batteries represent an ongoing advancement stemming from the extensive research conducted by the Nano and Molecular Systems Research Unit at the University of Oulu. This research focuses on the theoretical and modeling aspects of quantum devices, including superconducting qubits and quantum processors.
Journal Reference:
Mohan, B., et al. (2026) Fundamental Limitations on the Reliabilities of Power and Work in Quantum Batteries. PRX Quantum. DOI:10.1103/fnv6-yqmk. https://journals.aps.org/prxquantum/abstract/10.1103/fnv6-yqmk.