Demonstration of Maxwell demon-assisted Einstein-Podolsky-Rosen steering via superconducting quantum processor

The concept of Maxwell demon plays an essential role in connecting thermodynamics and information theory, while entanglement and nonlocality are fundamental features of quantum theory. Given the rapid advancements in the field of quantum information science, there is a growing interest and significance in investigating the connection between Maxwell demon and quantum correlation. The majority of research endeavors thus far have been directed toward the extraction of work from quantum correlation through the utilization of Maxwell demon. Recently, a novel concept called Maxwell demon-assisted Einstein-Podolsky-Rosen (EPR) steering has been proposed, which suggests that it is possible to simulate quantum correlation by doing work. This seemingly counterintuitive conclusion is attributed to the fact that Alice and Bob need classical communication during EPR steering task, a requirement that does not apply in the Bell test. In this study, we demonstrate Maxwell demon-assisted EPR steering with superconducting quantum circuits. By compiling and optimizing a quantum circuit to be implemented on a 2D superconducting chip, we were able to achieve a steering parameter of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:msub><a:mi>S</a:mi><a:mn>2</a:mn></a:msub><a:mo>=</a:mo><a:mn>0.770</a:mn><a:mo>±</a:mo><a:mn>0.005</a:mn></a:mrow></a:math> in the case of two measurement settings, which surpasses the classical bound of <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mn>1</b:mn><b:mo>/</b:mo><b:msqrt><b:mn>2</b:mn></b:msqrt></b:mrow></b:math> by 12.6 standard deviations. In addition, experimental observations have revealed a linear correlation between the nonlocality demonstrated in EPR steering and the work done by the demon. Considering the errors in practical operation, the experimental results are highly consistent with theoretical predictions. Our findings not only suggest the presence of a Maxwell demon loophole in the EPR steering, but also contribute to a deeper comprehension of the interplay between quantum correlation, information theory, and thermodynamics. Published by the American Physical Society 2024