Stoichiometric rare-earth crystals for novel integrated quantum memories

用于新型集成量子存储器的化学计量稀土晶体

• 批准号: EP/V002902/1
• 负责人: Margherita Mazzera
• 金额: $ 48.32万
• 依托单位: Heriot-Watt University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FV002902%2F1
• 关键词: Stoichiometric; rare; earth; crystals; novel

Quantum information science is the field of research that studies the information present in a quantum system. A number of new technological applications can be envisaged thanks to exquisitely quantum phenomena. While classical information encoding relies on bits, which can be either 0s and 1s, the quantum bits (or qubits) are associated to the state of quantum objects, e.g. single atoms, single spins, or single photons. Because of the quantum superposition principle, the qubits can then be 0s, 1s, or coherent superposition of both, thus giving access to an exceptionally richer alphabet. Quantum information science also exploits quantum entanglement, i.e. strong correlation between quantum objects, as a resource for fast and secure quantum communication protocols.In view of realising networks for quantum communication, quantum memories are fundamental devices as they act as interfaces between the photons, used as information carriers, and atoms, exploited for information storage and processing. To be useful in quantum networks, the quantum memories must fulfil specific requirements, as on-demand read-out, high efficiency and fidelity, long storage time, and multimodality. While atomic gases enabled the first remarkable quantum storage experiments, solid-state systems also offer interesting perspectives.Among these, the rare-earth doped crystals recently emerged as attractive candidates because they are ensembles of optically active ions naturally trapped in inert media, which do not require external trapping fields and ultra-high vacuum chambers. They have already featured performances equalising or overcoming those of trapped atoms or cold atomic ensembles in terms of efficiency and storage times. These crystals exhibit transitions both in the optical and in the radio- and micro-wave range, thus they could serve as photonic or microwave memories, but also as interfaces between optical and microwave frequencies, thus opening the way to hybrid systems employing superconducting devices.Despite their very promising performances and the milestone experiments realised in the last decade, a unique rare-earth doped crystal that fulfils all the requirements of an ideal photonic quantum memory does not yet exist.This project exactly tackles this problem and aims at developing a novel platform for telecom-compatible integrated quantum devices, containing solid-state quantum memories with unprecedented functionalities. The central idea is to employ not rare-earth doped crystals but stoichiometric crystals, i.e. where the rare-earth ions fully substitute one element of the crystal matrix, with the two-fold aim of increasing the absorption of light and narrowing the inhomogeneous linewidth of the electronic transitions, thanks to a lower local mechanical stress.The challenges addressed are:- the optimisation of the coherence properties of bulk crystals that will enable the implementation of quantum storage protocols, never demonstrated in these kind of materials; - the exploration of confined environment, i.e. laser written waveguides, for the realisation of integrated quantum memories.We expect the waveguide fabrication to facilitate the realisation of fibre-coupled devices and the efficient manipulation of the atomic transitions by means of electric fields, and to boost the interaction strength between the light and the rare-earth ions. This might give access to the storage of telecom light exploiting optical transitions that in diluted bulk samples would be too weak. Therefore, the proposed platform might permit the simultaneous demonstration of efficient, long-lived and multiplexed storage devices, which are also compatible with existing telecom fibre network. Such quantum memories would outperform the existing quantum storage devices, and their demonstration would open new avenues for the use of solid-state technologies for real quantum information applications.

量子信息科学是研究量子系统中存在的信息的研究领域。得益于精美的量子现象，可以设想许多新的技术应用。虽然编码的经典信息依赖于位，即可以是0和1s，但量子位（或Qubits）与量子对象的状态相关联，例如单个原子，单旋或单光子。由于具有量子叠加原理，因此Qubits可以是两者的0s，1s或相干叠加，从而可以访问一个异常丰富的字母。量子信息科学还利用了量子纠缠，即量子对象之间的强相关性，作为快速和安全的量子通信协议的资源。为了在量子网络中有用，量子记忆必须满足特定的要求，例如按需读取，高效率和忠诚度，较长的存储时间和多模式。虽然原子气体能够实现第一个显着的量子储存实验，但固态系统也提供了有趣的观点。在这些方面，最近出现的稀土掺杂晶体最近出现为有吸引力的候选物，因为它们是自然陷入惰性媒体的光学活性离子的组合，这些离子不需要惰性媒体，这些离子不需要外部诱捕场和超高的真空腔室。在效率和存储时间方面，他们已经以均衡或克服被困原子或冷原子合奏的表演。这些晶体在光学和无线波和微波范围内都表现出过渡，因此它们可以充当光子或微波记忆，也可以作为光学和微波频率之间的接口，从而为运用超导设备的混合系统开辟了道路。理想的光子量子记忆尚不存在。该项目恰好解决了此问题，并旨在为电信兼容兼容的集成量子设备开发一个新颖的平台，其中包含具有前所未有的功能的固态量子记忆。核心思想是要不采用稀土掺杂的晶体，而是使用化学计量的晶体，即稀有晶体完全代替晶体基质的一个要素，其两倍的目的是增加光的吸收并缩小范围内的范围，这要归功于较低的当地机械构成，占据了较低的属性。可以实现量子存储方案的晶体，在这种材料中从未证明； - 探索狭窄环境的探索，即激光书面波导，以实现综合量子记忆。我们期望波导的制造能够促进纤维耦合器件的实现，并通过电场来实现原子能过渡的有效操纵，以增强光线和稀有的稀有和稀有的互动强度。这可能会使电信光的存储利用光学转换，而光学过渡则太弱了。因此，所提出的平台可能允许同时证明高效，寿命和多重存储设备，这些设备也与现有的电信光纤网络兼容。这样的量子记忆将胜过现有的量子存储设备，其演示将为使用固态技术用于实际量子信息应用程序开辟新的途径。