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arXiv · 2404.18745

Positive and non-positive measurements in energy distillation from quantum batteries

Paranjoy Chaki·Aparajita Bhattacharyya·Kornikar Sen·Ujjwal Sen
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Abstract

We investigate energy distillation from quantum batteries within the framework of generalized quantum measurements, including both positive operator-valued measurements (POVMs) and physically realizable non-positive operator-valued measurements (NPOVMs) performed on an auxiliary system coupled to the battery. Two classes of NPOVMs, namely type-1 and type-2, are analyzed in the presence of environmental noise acting on the auxiliary system. We derive general expressions for the distillable energy corresponding to positive and non-positive measurements and show that the distillable energy obtained via NPOVMs remains robust against environmental noise. For a specific model, we demonstrate that the energy extracted using type-1 NPOVMs exceeds or equals that obtained via POVMs under amplitude-damping, dephasing, and bit-flip noise, while type-2 NPOVMs outperform POVMs under amplitude-damping noise. These results establish a clear operational advantage of NPOVMs for energy extraction. We also analyze restricted measurement settings and compare the accessible distillable energy for constrained positive and type-1 non-positive measurements.

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Paranjoy Chaki, Aparajita Bhattacharyya, Kornikar Sen, Ujjwal Sen. 2024-04-29. Positive and non-positive measurements in energy distillation from quantum batteries. https://doi.org/10.1016/j.physleta.2026.132050

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