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arXiv 2012.06114gr-qchep-th
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开放引力系统的量子几何流和相干性:与热标量场耦合的圈量子引力

Quantum geometrical current and coherence of the open gravitation system: loop quantum gravity coupled with a thermal scalar field

Hong Wang, Jin Wang

摘要:

开放量子系统与环境的相互作用经常表现出有趣的行为,如退相干、非么正演化、耗散等。研究开放量子引力系统与环境的相互作用是一个有趣但又具有挑战性的课题。在这项工作中,我们发展了一个开放的量子引力系统的一般参数化的理论框架。在Born-Markov近似下,我们用一种新的方法导出了量子主方程,它决定了某些类型的开放量子引力系统的演化。最后,我们研究了一个特定的模型,其中实标量场扮演环境的角色,并且假设时空是均匀且各向同性的。我们通过圈量子引力来模拟时空。证明了当标量场处于热平衡时,标量场可以诱导出平衡态的量子几何。对于非稳态,量子几何通量出现。指出量子几何通量和相干性可以驱动时空几何的演化。这为我们研究时空几何的演化提供了一个新的视角。我们的结果表明,时空的相干性单调减少的浴温度降低。这表明一个经典的冷宇宙可以从一个初始的热量子宇宙中产生。我们发现在这个模型中引力系统的纠缠熵与空间的平均体积有关。在研究圈量子宇宙学时,我们取连续极限,近似地得到了时空从零体积态到有限体积态的隧穿几率。

英文摘要:

Open quantum systems interacting with the environments often show interesting behaviors, such as decoherence, non-unitary evolution, dissipation, etc. It is interesting but still challenging to study the open quantum gravitation system interacting with the environments. In this work, we develop a general parameterized theoretical framework for the open quantum gravitation system. Under the Born-Markov approximation, we derived the quantum master equation with a new method which determines the evolution for certain types of open quantum gravitation system. Finally, we studied a specific model where the real scalar field plays the role of the environment and the spacetime is assumed to be homogeneous and isotropic. We quantize the spacetime through the loop quantum gravity. We show that the scalar field can induce the quantum geometry in the equilibrium state when the scalar field is under the thermal equilibrium. For the non-steady state, the quantum geometry flux emerges. We point out that the quantum geometry flux and the coherence can drive the evolution of the spacetime geometry. This provides us a new view on the evolution of the spacetime geometry. Our results shown that the coherence of the spacetime monotonically decreases as the temperature of the bath decreases. This indicates that a classical cold universe can emerge from an initial hot quantum universe. We found in this model that the entanglement entropy of the gravitation system is related to the average volume of the space. We take the continuous limit for studying the loop quantum cosmology and approximately obtain a tunneling probability of the spacetime from the zero volume state to the finite volume state.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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