坍缩物体的辐射显然是幺正的
Radiation from a collapsing object is manifestly unitary
摘要：
引力坍缩过程激发了背景几何中传播的场，并产生热辐射。我们证明了明确的计算，对应于这种辐射的密度矩阵实际上描述了一个纯态。当Hawking的首阶密度矩阵只包含对角项时，我们计算了非对角关联项。这些相关性开始非常小，但随后会随着时间的推移而增长。累积效应是相关性变得与首阶项相当，并显著修改了密度矩阵。虽然霍金的密度矩阵平方的轨迹在演化过程中偏离1，但总的密度矩阵平方的轨迹在所有时间和所有频率都保持1。这意味着坍缩物体的辐射过程是么正的。
英文摘要：
The process of gravitational collapse excites the fields propagating in the background geometry and gives rise to thermal radiation. We demonstrate by explicit calculations that the density matrix corresponding to such radiation actually describes a pure state. While Hawking's leading order density matrix contains only the diagonal terms, we calculate the off-diagonal correlation terms. These correlations start very small, but then grow in time. The cumulative effect is that the correlations become comparable to the leading order terms and significantly modify the density matrix. While the trace of the Hawking's density matrix squared diverges from unity during the evolution, the trace of the total density matrix squared remains unity at all times and all frequencies. This implies that the process of radiation from a collapsing object is unitary.
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。
