Quantum Technology

One of the key components of many quantum technologies, as long-distance communications and quantum computing, are quantum light memories. Rare-earth doped crystals (RE) are one of the preferred materials of researchers for developing those memories because they show high-efficiency, long storage time and broad bandwidth when used for quantum storage of light.

Those materials, in the form on nanofilms or nanoparticles, have previously shown long optical and spin coherence lifetimes and can offer flexibility in design, composition and integration. Nevertheless, their capabilities concerning quantum coherence, that is maintaining quantum states for long lifetimes, have proven very difficult at this tiny scale. The higher concentration of defects and significant surface effects are often observed in these systems, hindering their use for quantum communication and computing.

Now a team of researchers, led by Professor Philippe Goldner from Chimie ParisTech, PSL University- CNRS and member of the Quantum Flagship’s project SQUARE, have been able to overcome this issue by testing such capabilities on rare-earth dope nanoparticles using the Stark echo modulation memory protocol (SEMM), an on-demand electro-optic quantum protocol. In their experiment, they selected Eu^3+:Y₂O₃ nanoparticles of 100 nm diameter and were able to demonstrate, at 1.3 K and using weak electric fields, coherent storage of light, a memory time up to 40 µs, a frequency-multiplexed storage capability, and an extremely high fidelity between the input and output signals, an essential requirement for efficient quantum memories.

All of these findings, published a study in the journal NanoLetters, show that nanoscale memories made of rare-earth-doped nanoparticles are capable of storing light efficiently, with more bandwidth and improved processing capabilities, making them promising candidates for developing multimode and long-storage quantum memories.

Contact information
Philippe Goldner
Institut de Recherche de Chimie Paris, Université PSL
Chimie ParisTech, CNRS, 75005 Paris
philippe.goldner@chimie-paristech.fr
Tel. 01 53 73 79 30

More information

• Reference: A. Fossati, S. Liu, J. Karlsson, A. Ikesue, A. Tallaire, A. Ferrier, D. Serrano, and P. Goldner*, Nano Letters 2020 20 (10), 7087-7093. DOI: 10.1021/acs.nanolett.0c02200

This study has been conducted within the framework of the European FET-Open NanOQTech project and the Quantum Flagship SQUARE project.