Optimal Continuous- to Discrete-Variable Bipartite Entanglement Conversion

TL;DR

This paper introduces optimal methods for converting continuous-variable entanglement into discrete-variable entanglement using local operations, enabling more feasible quantum technology implementations on bosonic systems.

Contribution

It presents two optimal schemes for CV to DV entanglement conversion, including maximal rate extraction and probabilistic high-entanglement production, with performance quantification and implementation strategies.

Findings

Maximally entangled qubit pairs achieved at maximal rate

Probabilistic generation of high-entanglement qudit pairs

Finite measurement rounds suffice despite infinite-dimensional CV resources

Abstract

Discrete-variable (DV) entanglement is crucial for numerous quantum applications, yet its deterministic generation in many bosonic systems remains experimentally challenging. In contrast, continuous-variable (CV) entanglement can be produced efficiently. We propose two optimal schemes for converting CV bipartite entanglement into DV entanglement using only local operations and classical communication. The first scheme extracts maximally entangled qubit pairs at the theoretically maximal rate, while the second probabilistically produces a maximally entangled qudit pair with the highest average entanglement. In both schemes, we quantify the optimal performance and identify the measurement operators required for implementation. Notably, using only a sequence of binary measurements, our approach can succeed in a finite number of measurement rounds on average, even though the CV resource is infinite-dimensional. Our schemes improve the feasibility of implementing DV-based quantum technologies on bosonic platforms.