2 research outputs found
Hybrid filtering for a class of nonlinear quantum systems subject to classical stochastic disturbances
A hybrid quantum-classical filtering problem, where a qubit system is
disturbed by a classical stochastic process, is investigated. The strategy is
to model the classical disturbance by using an optical cavity. Relations
between classical disturbances and the cavity analog system are analyzed. The
dynamics of the enlarged quantum network system, which includes a qubit system
and a cavity system, are derived. A stochastic master equation for the
qubit-cavity hybrid system is given, based on which estimates for the state of
the cavity system and the classical signal are obtained. The quantum extended
Kalman filter is employed to achieve efficient computation. Numerical results
are presented to illustrate the effectiveness of our methods.Comment: 12 pages,8 figures, to be published on IEEE Transactions on
Cybernetic
Generation of accessible sets in the dynamical modelling of quantum network systems
In this paper, we consider the dynamical modeling of a class of quantum
network systems consisting of qubits. Qubit probes are employed to measure a
set of selected nodes of the quantum network systems. For a variety of
applications, a state space model is a useful way to model the system dynamics.
To construct a state space model for a quantum network system, the major task
is to find an accessible set containing all of the operators coupled to the
measurement operators. This paper focuses on the generation of a proper
accessible set for a given system and measurement scheme. We provide analytic
results on simplifying the process of generating accessible sets for systems
with a time-independent Hamiltonian. Since the order of elements in the
accessible set determines the form of state space matrices, guidance is
provided to effectively arrange the ordering of elements in the state vector.
Defining a system state according to the accessible set, one can develop a
state space model with a special pattern inherited from the system structure.
As a demonstration, we specifically consider a typical 1D-chain system with
several common measurements, and employ the proposed method to determine its
accessible set