We applied the thermofield dynamics formalism to analyze how the non-classical properties of the Bell-cat states are influenced by a gradual change of temperature values, in a thermal equilibrium system. To this purpose we calculate the thermal Wigner functions for these states, whose negative volume is associated with non-classical properties, and we evaluate how these non-classical features vary with temperature. Our results indicate that these properties are almost absent for temperatures of around 2 K.

中文翻译：

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维格纳函数的负性和钟形猫状态的热效应

我们应用热场动力学形式主义来分析在热平衡系统中，钟形猫的非经典属性如何受到温度值的逐渐变化的影响。为此，我们计算了这些状态的热Wigner函数，其负体积与非经典属性相关联，并且我们评估了这些非经典特征如何随温度变化。我们的结果表明，大约2 K的温度几乎没有这些特性。