近日，西班牙马德里材料科学研究所的Sigmund Kohler及其研究团队取得一项新进展。经过不懈努力，他们揭示了准能锥形交点处的量子耗散过程。相关研究成果已于2024年11月18日在国际知名学术期刊《物理评论A》上发表。

该研究团队研究了准能量锥形交点附近的弗洛凯态的性质，并探讨了驱动的两能级系统耦合到欧姆热浴时，其潜在的时空对称性所带来的影响。

研究发现，在准能量分裂恒定的流形上，弗洛凯态的平均能量会连续交换。在存在耗散的情况下，稳态布居的参数依赖性通常与平均能量的参数依赖性相似。反过来，平均能量也是长时间极限下密度算子定性行为的一个指标。

对称性的另一个后果是，对于特定的驱动参数，即使在任意低的温度下，稳态也可能是完全混合的。对于较大的驱动频率，在交点的整个附近都会发现具有最大熵的状态，这可以用此极限下出现的手性来解释。研究人员通过数值数据说明了超出高频近似范围的分析结果。

附：英文原文

Title: Quantum dissipation at conical intersections of quasienergies

Author: Sigmund Kohler

Issue&Volume: 2024/11/18

Abstract: We investigate the properties of Floquet states in the vicinity of a conical intersection of quasienergies and work out the consequences of the underlying spatio-temporal symmetries for a driven two-level system coupled to an ohmic heat bath. We find that on manifolds with constant quasienergy splitting, the mean energies of the Floquet states are continuously interchanged. In the presence of dissipation, the parameter dependence of the stationary populations generally resembles that of the mean energies. In turn, the mean energies are an indicator for the qualitative behavior of the density operator in the long-time limit. A further consequence of the symmetries is that for specific driving parameters, the stationary state may be fully mixed even at arbitrarily low temperatures. For large driving frequencies, such states with maximal entropy are found in the whole vicinity of the intersection, which can be explained by a chirality emerging in this limit. Analytical results beyond a high-frequency approximation are illustrated by numerical data.

DOI: 10.1103/PhysRevA.110.052218

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.052218