Generation of quantum entangled state via continuous feedback control

Abstract

In this paper, we consider a stabilization problem of a two-qubit system under continuous measurement. Our objective is to stabilize two types of quantum entangled state which play an important role in quantum information technology. In this paper, we show that the global stabilization at a specific quantum entangled state by continuous inputs is possible. An effectiveness of the control input is verified by numerical simulation.

Feedback preparation of maximally entangled states of two‐qubit systems

“…When the atomic detuning parameter satisfies the compensation condition, the free Hamiltonian in the system master equation vanishes. The case of has been studied in [31, 41].…”

“…For a pure‐state quantum system of two symmetric qubits, several smooth controls in the frame of polar coordinates were designed and almost global stabilisation in a special Bell state was achieved [40]. For two‐qubit quantum systems, one degenerate measured observable and two control Hamiltonians were used to globally stabilise a desired Bell state where two different smooth control laws were required [41]. Non‐smooth control means that different control laws are utilised in different state sets (e.g.…”

Local State Transition of Feedback Controlled Quantum Systems with Imperfect Detector Efficiency: Part II: Accessibility Analysis for Quantum Systems

“…For examples, feedback control laws for a specific class of quantum systems (spin systems) attaining global asymptotic stabilization were proposed by employing techniques of stochastic control theory [9]- [11]. These results have significant importance, because spin is a physical realization of quantum bit (qubit or Qbit for short) which is the unit of quantum information processing.…”