Improving the capacity of quantum dense coding from decoherence of finite temperature using parity-time symmetric operations

This paper explores enhancing quantum dense coding capacity in finite-temperature decoherence environments via parity-time ( PT ) symmetric operations. We derive the master equation for a two-qubit system in a thermal bath, analyzing dense coding dynamics with and without PT symmetry operations. Without PT operations, the quantum dense coding capacity is highly sensitive to temperature parameter and decoherence rate, losing its advantage at high temperatures. Introducing a local PT symmetric operation on one qubit restores and surpasses the noiseless capacity. Additionally, numerical analysis demonstrates that by adjusting the non-Hermiticity, the optimal protection rate can always exceed 1. Our findings demonstrate PT symmetric operations as a novel tool to protect quantum correlations and enhance information transmission in realistic thermal settings, offering insights for robust quantum communication protocols.