No-go theorems for universal entanglement purification

Physical Review Letters (2025)

 

Scientists look at ways to clean up noisy quantum entanglement by combining several imperfect entangled pairs into one better pair — a process called entanglement purification.

The authors of this paper show that, if limited to standard tools such as local operations and classical communication, there’s no method that guarantees improvement for all types of two-qubit entangled states. However, for entangled states with special structures, improvement is possible.

The paper authors are Allen Zang, Xinan Chen, Eric Chitambar, Martin Suchara and Tian Zhong, who conducted their work at the University of Chicago, the University of Illinois Urbana-Champaign and Microsoft.