Quantum thermodynamics is a blossoming field that aims to bridge the gap between quantum physics and thermodynamics. In this report, we firstly introduce the battery capacity as a figure of merit that expresses the potential of a quantum system to store and supply energy. This function is closely linked with the entropy of the battery state, as well as measures of coherence and entanglement. We then present an experimental verification of battery capacity and its relationships with other quantum characters of battery using two-photon states. We finally introduce an operational thermodynamics speed to quantify the extracting work and show both coherence and entanglement of quantum systems can speed up work extracting. This reveals a new thermodynamic method to witness entangled systems.

Ming-Xing Luo is a full professor at Southwest Jiaotong University, China. He focuses on quantum information, quantum networks, and quantum batteries. He has published more than 100 academic papers in prestigious international journals such as Rep. Prog. Phys., Phys. Rev. Lett., Cell Rep. Phys. Sci., npj Quantum Inf., and IEEE JSAC.