High Efficiency Multimode Quantum Memory Using Atomic Frequency Combs in an Optical Cavity

George Mason University, Fairfax VA

Investigators

Abstract

Quantum memory that faithfully stores and retrieve quantum states is a basic building block for quantum repeaters in long-distance quantum communication. Among the existing approaches to implementing quantum memories, the atomic frequency comb (AFC) in rare-earth ensemble is identified for its outstanding potential, which includes memory efficiency up to 100%, high fidelity, long storage times up to seconds, a large time-bandwidth product for a high bit rate up to gigabit/s, multi-mode capacity, a large range of operational wavelengths, and being solid-state with a relatively simple setup using off-the-shelf components. Achieving high efficiency is the corner stone to fully realize theis potential. Currently, the two major obstacles preventing optimal efficiency are the low absorption length and poorly-formed spectral and spatial structures in the AFC. In this NSF supported project, two novel schemes are combined to solve the problems: employing a low finesse optical cavity to boost the absorption length, and using various temporal, spectral and spatial configurations to optimize the AFC structure. The main efforts will focus on understanding the physics and developing critical enabling techniques in preparing the AFC in rare-earth ensembles and in the storage/retrieving process. We plan to use thulium ions doped crystals as prototype materials to develop and test the schemes. The resulting methods and techniques are expected to be applicable to similar rare-earth ensembles. The supported project will have broad impact in advancing quantum information science and technology. The project aims at great advances in quantum memories towards practical devices, which will find applications in both long-distance quantum communication and distributed quantum computation. The investigation will also lead to better understanding of quantum theory, such as decoherence, entanglement, and quantum no-cloning theorem. Education is an important component in this project. The efforts focus on cultivating a new generation of scientists and engineers in quantum information-related fields and contributing to the diversity of the scientific workforce. An on-line quantum mechanics course will be developed for high school science teachers so that our K-12 school system will be better prepared to introduce quantum concepts to students at young age. Undergraduate and graduate students will be recruited to the field by introducing new developments in the quantum information frontier into existing quantum mechanics courses, and by providing students research opportunities in the project.