Noiseless linear amplification for Einstein-Podolsky-Rosen steering swapping

Abstract

Entanglement swapping, a crucial technique for establishing a global quantum network, enables independent quantum states to become entangled without direct interaction. This remarkable technique can also be effectively applied to Einstein-Podolsky-Rosen (EPR) steering swapping. EPR steering, which is a kind of quantum correlation between entanglement and Bell nonlocality, is considered as a valuable resource for secure quantum communication. However, in practical applications, quantum states often need to be transmitted over long distances before entanglement or steering swapping. Unfortunately, unavoidable loss and noise will degrade the correlation characteristics of quantum states. As a result, it may become difficult to generate steering after steering swapping. In this paper, we propose the application of noiseless linear amplification (NLA) technology to the EPR steering swapping for the first time. We theoretically analyze the effects of NLA on steering swapping. Results indicate that NLA can change the original channel optimal gain, effectively expand the range of achievable channel gain and the transmission distance. It can also tolerate higher levels of excess noise, and improve the steerability of quantum states. Steering swapping has important applications in building wide area quantum communication networks, thus paving the way for the establishment of reliable and efficient global quantum networks.