Bonn 2025 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

QI: Fachverband Quanteninformation

QI 14: Quantum Entanglement III

QI 14.5: Talk

Tuesday, March 11, 2025, 15:15–15:30, HS IX

Statistical evaluation and optimization of entanglement purification protocols — •Francesco Preti^{1, 2} and Jószef Zsolt Bernád¹ — ¹Forschungszentrum Juelich, Institute of Quantum Control (PGI-8), D-52425 Juelich, Germany — ²Institute for Theoretical Physics, University of Cologne, D-50937 Koeln, Germany

Quantitative characterization of two-qubit entanglement purification protocols is introduced. Our approach is based on the concurrence and the hit-and-run algorithm applied to the convex set of all two-qubit states. We demonstrate that pioneering protocols are unable to improve the estimated initial average concurrence of almost uniformly sampled density matrices, however, as it is known, they still generate pairs of qubits in a state that is close to a Bell state. We also develop a more efficient protocol and investigate it numerically together with a recent proposal based on an entan- gling rank-2 projector. Furthermore, we present a class of variational purification protocols with continuous parameters and optimize their output concurrence. These optimized algorithms turn out to surpass former proposals and our protocol by means of not wasting too many entangled states.

Keywords: Entanglement purification; Optimization; Variational algorithms