# The success probability in the recovery step versus the damping probability *p*

**Figure 5.** The success probability in the recovery step versus the damping probability *p*. (a) α = 0.7, β = 0.35, γ = 0.4, δ = 0.48. (b) α = 0.10, β = 0.55, γ = −0.60, δ = 0.57. The solid curve is the success probability without a preparation step while the other three curves with symbols are the success probability with a preparation step.

**Abstract**

Quantum entanglement is a critical resource for quantum information and quantum computation. However, entanglement of a quantum system is subjected to change due to the interaction with the environment. One typical result of the interaction is the amplitude damping that usually results in the reduction of the entanglement. Here we propose a protocol to protect quantum entanglement from the amplitude damping by applying Hadamard and CNOT gates. As opposed to some recently studied methods, the scheme presented here does not require weak measurement in the reversal process, leading to a faster recovery of entanglement. We propose a possible experimental implementation based on linear optical system.