Quantum steering is a stronger form of quantum entanglement and is considered to rigorously address the nonlocal correlation in the original Einstein–Podolsky–Rosen paradox. We study the quantum steerability of two classes of continuous-variable (CV) entangled states that are most often employed for CV quantum informatics-entangled coherent states (ECSs) and two-mode-squeezed vacuum (TMSV). We test the two steering criteria by utilizing Heisenberg and entropic uncertainty relations, respectively, and find that the latter can reveal the steerability of ECSs of any size and parity, whereas the former scarcely can. The steering behaviors of the two states are investigated and compared when they experience a noisy environment, i.e., an amplitude damping channel. When the noise is added asymmetrically, e.g., when only one party of the bipartite system is subject to noise, quantum steering can be possible only in one direction, e.g., Alice on Bob’s state but not Bob on Alice’s state. We show the emergence of this one-directional steering for both ECSs and the TMSV in a certain parameter range under decoherence.
© 2013 Optical Society of America
Original Manuscript: April 18, 2013
Manuscript Accepted: June 25, 2013
Published: August 26, 2013
Chang-Woo Lee, Se-Wan Ji, and Hyunchul Nha, "Quantum steering for continuous-variable states," J. Opt. Soc. Am. B 30, 2483-2490 (2013)