Reduced Operator Approximation for Modelling Open Quantum Systems

Adiabatic approximation in open quantum systems

We generalize the standard quantum adiabatic approximation to the case of open quantum systems. We define the adiabatic limit of an open quantum system as the regime in which its dynamical superoperator can be decomposed in terms of independently evolving Jordan blocks. We then establish validity and invalidity conditions for this approximation and discuss their applicability to superoperators ...

Conservation law of operator current in open quantum systems

open quantum systems

Quantum mechanics must be regarded as open systems. On one hand, this is due to the fact that, like in classical physics, any realistic system is subjected to a coupling to an uncontrollable environment which influences it in a non-negligible way. The theory of open quantum systems thus play a major role in many applications of quantum physics since perfect isolation of quantum system is not po...

Continuously Diagonalized Density Operator of Open Systems

We showed several years ago that the density operator of Markovian open systems can be diagonalized continuously in time. The resulting pure state jump processes correspond to quantum trajectories proposed in recent quantum optics calculations or, at fundamental level, to exact consistent histories. The quantum state of an open quantum system — actually a subsystem of a closed one — cannot be d...

Gaussian Stochastic Linearization for Open Quantum Systems Using Quadratic Approximation of Hamiltonians

This paper extends the energy-based version of the stochastic linearization method, known for classical nonlinear systems, to open quantum systems with canonically commuting dynamic variables governed by quantum stochastic differential equations with non-quadratic Hamiltonians. The linearization proceeds by approximating the actual Hamiltonian of the quantum system by a quadratic function of it...