Abrupt decay of entanglement and quantum communication through noise channels

Charles H. Bennett, Christopher A. Fuchs, John A. Smolin

NASSER METWALLY

We investigate the dynamics of two qubits state through the Bloch channel. It is found that the degradation and sudden-death of the entanglement depend on the channel's parameters and the structure of the input state. Starting from partially entangled states as input state, the output states are more robust compared with those obtained from initial maximally entangled states. Also the survivability of entanglement increased as the absolute equilibrium values of the channel increased or the ratio between the longitudinal and transverse relaxation times gets smaller. Ability of using the output states as quantum channels to perform quantum teleportation is investigated. The idea that the useful output states are used to achieve the original quantum teleportation protocol is discussed.

J. P. Gordon

Hui Li

This study calculates the evolution of local quantum uncertainty (LQU) in open quantum systems under various noise conditions, including amplitude damping, depolarizing, phase damping, and their combinations. Using the operator-sum representation, we analyze the behavior of LQU for a quantum state and reveal distinct patterns of LQU changes under different noise types. Our results show that while quantum entanglement often experiences sudden death, LQU exhibits more resilience, with abrupt changes observed under specific noise combinations. Notably, we find that phase damping noise, which induces random phase fluctuations without energy loss, leads to unique behaviors in LQU. This work provides novel insights into the robustness of quantum states against noise, highlighting the importance of distinguishing between different noise mechanisms in quantum information processing. Our findings contribute to the development of strategies for mitigating noise effects in quantum communication and computing.

A.‐S. F. Obada, N.M. Arafa, NASSER METWALLY

We investigate the entanglement dynamics of maximum and partial entangled two-qubit states, where each qubit interacts locally with its own noise environment. In the presence of local non-correlated noise, the entangled system loses its entangled properties faster than that depicted for correlated noise. The capacity of the output channel decays gradually and smoothly in the presence of non-correlated noise and hastily for the correlated one. We show that the local non-correlated noise can improve the capacity of the output channel. The possibility of using the output state to perform quantum teleportation is discussed and the effect of the noise parameter on the fidelity of the teleported state is investigated.

Nan Wang, Shi‐Yan Li, Wei-Yue Zhang +3 more