Quantum steering for two-mode states with continuous-variable in laser channel

Einstein–Podolsky–Rosen (EPR) steering is an important resource for one-sided device-independent quantum information processing. This steering property can be destroyed by the interaction between a quantum system and its environment in practical applications. In this paper, we employ the characteristic function representation of probability distributions to investigate the quantum steering of two-mode continuous-variable states in a laser channel, where both the gain factor and the loss effect are taken into account. Firstly, we analyse the steering time of the two-mode squeezed vacuum state under one-mode and two-mode laser channels, respectively. We find that the gain process introduces additional noise into the two-mode squeezed vacuum state, thereby reducing the steerable time. Secondly, by quantifying EPR steering, we show that two-side loss exhibits smaller steerability than one-side loss, although they share the same two-way steerable time. In addition, we find that the more-gained party can steer the other party’s state, whereas the other party cannot steer the gained party beyond a certain threshold value. In this sense, the gain effect in one party appears to be equivalent to the loss effect in the other party. Our results pave the way for the distillation of EPR steering and quantum information processing in practical quantum channels.