Analyzing Density Operator in Thermal State for Complicated Time-Dependent Optical Systems

Abstract EN

Density operator of oscillatory optical systems with time-dependent parameters is analyzed.

In this case, a system is described by a time-dependent Hamiltonian.

Invariant operator theory is introduced in order to describe time-varying behavior of the system.

Due to the time dependence of parameters, the frequency of oscillation, so-called a modified frequency of the system, is somewhat different from the natural frequency.

In general, density operator of a time-dependent optical system is represented in terms of the modified frequency.

We showed how to determine density operator of complicated time-dependent optical systems in thermal state.

Usually, density operator description of quantum states is more general than the one described in terms of the state vector.