Influence of homodyne-based feedback control on the entropic uncertainty in open quantum system

• Published in: Chinese physics B Vol. 28; no. 7; p. 70303
• Main Authors: Hu, Juju, Xue, Qin
• Format: Journal Article
• Language: English
• Published: 01.07.2019
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/28/7/070303

For an open quantum system containing two qubits under homodyne-based feedback control, we investigate the dynamical behaviors of quantum-memory-assisted entropic uncertainty. Moreover, we analyze the influence of feedback modes and coefficients on the entropic uncertainty. Numerical investigations show that the memory qubit should be placed in a non-dissipative channel if the single dissipative channel condition can be chosen, which helps reduce the entropic uncertainty of the system. For the homodyne feedback control F = λ σ x (or F = λ σ y ) , due to different roles of the entangled qubits A and B, when they are subject to feedback control with different feedback coefficients λ , the exchange of feedback coefficients will cause variations of the entropic uncertainty. When the feedback coefficient corresponding to the memory qubit B is larger ( λ B > λ A ) , the steady value of the entropic uncertainty will be small, which is conducive to enhancing the robustness of the system. However, for the feedback control F = λ σ z , the difference between the feedback coefficients has no effect on the steady values of the entropic uncertainty.