Temporal multimode storage of entangled photon pairs

TL;DR

This paper demonstrates the simultaneous storage and retrieval of multiple entangled photon pairs in a solid-state quantum memory, showcasing a ten-mode temporal multimode capacity and introducing a new entanglement certification method.

Contribution

It presents the first demonstration of temporal multimode storage of entangled photons in a solid-state memory with a novel indirect entanglement witness technique.

Findings

Achieved storage and retrieval of two entangled photon pairs.

Measured a temporal multimode capacity of ten modes.

Developed a new method for certifying entanglement in multiplexed memories.

Abstract

Multiplexed quantum memories capable of storing and processing entangled photons are essential for the development of quantum networks. In this context, we demonstrate the simultaneous storage and retrieval of two entangled photons inside a solid-state quantum memory and measure a temporal multimode capacity of ten modes. This is achieved by producing two polarization entangled pairs from parametric down conversion and mapping one photon of each pair onto a rare-earth-ion doped (REID) crystal using the atomic frequency comb (AFC) protocol. We develop a concept of indirect entanglement witnesses, which can be used as Schmidt number witness, and we use it to experimentally certify the presence of more than one entangled pair retrieved from the quantum memory. Our work puts forward REID-AFC as a platform compatible with temporal multiplexing of several entangled photon pairs along with a new entanglement certification method useful for the characterisation of multiplexed quantum memories.