The approaching era will require computing resources that are future proof across various domains, extending from communications, computing and sensing. It is anticipated that quantum computing will play a major role due to limitations of classical computing. A vital factor in meeting this capability is the need of a non-classical storage unit to facilitate the quantum devices. Therefore, quantum memory becomes a necessity. This paper aims to present detailed discussion on quantum memory, which would begin from fundamental concepts and would range to a more advanced level, with the ultimate goal of identifying the most suitable method for developing quantum applications. The current protocols utilized in quantum memories rely on optically driven and photon echo based techniques. The survey will deeply analyze the processes and principles involved in storing and retrieving information using these methods. It would also assess their key features, including retention time, efficiency, measurement fidelity, bandwidth, and necessary conditions. In addition, the focus would also be on studying the neoteric realms of quantum dots and the Bose Einstein condensates. The paper concludes with challenges in building quantum memories and possible future directions.
The approaching era will require computing resources that are future proof across various domains, extending from communications, computing and sensing. It is anticipated that quantum computing will play a major role due to limitations of classical computing. A vital factor in meeting this capability is the need of a non-classical storage unit to facilitate the quantum devices. Therefore, quantum memory becomes a necessity. This paper aims to present detailed discussion on quantum memory, which would begin from fundamental concepts and would range to a more advanced level, with the ultimate goal of identifying the most suitable method for developing quantum applications. The current protocols utilized in quantum memories rely on optically driven and photon echo based techniques. The survey will deeply analyze the processes and principles involved in storing and retrieving information using these methods. It would also assess their key features, including retention time, efficiency, measurement fidelity, bandwidth, and necessary conditions. In addition, the focus would also be on studying the neoteric realms of quantum dots and the Bose Einstein condensates. The paper concludes with challenges in building quantum memories and possible future directions.
Abstract Quantum memory devices are essential components of integrated quantum-photonic circuits with applications in quantum computing and quantum information processing. The comprehension and quantification of critical properties such as fidelity, coherence time, storage time, and efficiency of quantum memory are insufficient in the extant literature. In this review, we examine the development and characteristics of various types of quantum memories. Although diverse approaches to storing quantum information are described in detail, we emphasize solid-state quantum memory. Furthermore, we discuss the fabrication and characterization of defects of quantum materials, including two-dimensional materials, for quantum memory applications. We survey theoretical tools such as density functional theory for studying defects to evaluate quantum properties.
This paper presents a novel design for a quantum memory utilizing the principles of quantum coherence. The core concept centers around constructing a quantum storage device with enhanced coherence properties, enabling higher storage density and extended storage times. Traditional quantum storage methods often suffer from limitations in coherence times, hindering their practical application. This design addresses this challenge by meticulously engineering the quantum system to maximize coherence, allowing for robust information storage and retrieval. We explore the theoretical framework and key design considerations, focusing on the manipulation and control of quantum states to achieve superior performance compared to existing technologies. The proposed architecture leverages recent advances in material science and quantum control techniques to establish a foundation for a high-performance quantum memory. The ultimate goal is to facilitate the development of scalable quantum computing architectures and advanced quantum information processing systems.
Quantum memory, which maps photonic quantum information into a stationary medium and retrieves it at a chosen time, plays a vital role in the advancement of quantum information science. In particular, the scalability of a quantum memory is a central challenge for quantum network that can be overcome by using integrated devices. Quantum memory with an integrated device is highly appealing since it not only expands the number of memories to increase data rates, but also offers seamless compatibility with other on-chip devices and existing fiber network, enabling scalable and convenient applications. Over the past few decades, substantial efforts have been dedicated to achieving integrated quantum memory using rare earth ions doped solid-state materials, color centers, and atomic gases. These physical platforms are the primary candidates for such devices, where remarkable advantages have been demonstrated in achieving high-performance integrated quantum memory, paving the way for efficiently establishing robust and scalable quantum network with integrated quantum devices. In this paper, we aim to provide a comprehensive review of integrated quantum memory, encompassing its background and significance, advancement with bulky memory system, fabrication of integrated device, and its memory function considering various performance metrics. Additionally, we will address the challenges associated with integrated quantum memory and explore its potential applications. By analyzing the current state of the field, this review will make a valuable contribution by offering illustrative examples and providing helpful guidance for future achievements in practical integrated quantum memory.
Optical photons are powerful carriers of quantum information, which can be delivered in free space by satellites or in fibers on the ground over long distances. Entanglement of quantum states over long distances can empower quantum computing, quantum communications, and quantum sensing. Quantum optical memories are devices designed to store quantum information in the form of stationary excitations, such as atomic coherence, and are capable of coherently mapping these excitations to flying qubits. Quantum memories can effectively store and manipulate quantum states, making them indispensable elements in future long-distance quantum networks. Over the past two decades, quantum optical memories with high fidelities, high efficiencies, long storage times, and promising multiplexing capabilities have been developed, especially at the single-photon level. In this review, we introduce the working principles of commonly used quantum memory protocols and summarize the recent advances in quantum memory demonstrations. We also offer a vision for future quantum optical memory devices that may enable entanglement distribution over long distances.
This paper investigates the potential of utilizing quantum memory for quantum information storage. Quantum memory offers a pathway towards robust and scalable quantum computing and communication by providing a means to retain quantum information, a fundamental requirement for any quantum technology. This work explores various mechanisms leveraging quantum effects within specific materials and systems to achieve long-term quantum storage. We examine theoretical frameworks and discuss the challenges and opportunities associated with developing practical quantum memory systems. The core claim is to explore the feasibility of using quantum memory for quantum information storage, focusing on the underlying mechanisms of maintaining quantum coherence. Key areas of investigation include coherence preservation strategies, error correction techniques specifically tailored for quantum memory, and the selection of appropriate materials exhibiting suitable quantum properties for enhanced storage duration. The ultimate goal is to lay the groundwork for future research into constructing stable and reliable quantum memory devices, crucial for realizing the full potential of quantum information processing. ---
Quantum technologies, for example, quantum communication and quantum computation, promise spectacular quantum enhanced advantages beyond what can be done classically. However, quantum states, as the element of quantum technologies, are very fragile and easily get lost to the environment, and meanwhile, their generation and quantum operations are mostly probabilistic. These problems make it exponentially hard to build long-distance quantum channels for quantum communication and large quantum systems for quantum computing. Quantum memory allows quantum states to be stored and retrieved in a programmable fashion, therefore providing an elegant solution to the probabilistic nature and associated limitation by coordinating asynchronous events. In the past decades, enormous advances in quantum memory have been made by developing various storage protocols and their physical implementations, and the quantum memory has gradually evolved from the initial conceptual demonstration to a nearly practical one. Aiming at being practicable for efficient synchronisation and physical scalability, an ideal quantum memory should meet several key features known as high efficiency, low noise level, large time bandwidth product (lifetime divided by pulse duration) and operating at room temperature. Here, we present the research status and development trends of this field by introducing some typical storage protocols. Among these protocols, a room-temperature broadband quantum memory is the most attractive due to its simplicity and practicability. However, at room temperature, noise becomes dominant and is a bottleneck problem that has impeded the realization of a real room-temperature broadband quantum memory in the last decades. Recently, the noise problem has been solved in two memory protocols, i.e. FORD (far off-resonance Duan-Lukin-Cirac-Zoller) protocol and ORCA (off-resonant cascaded absorption) protocol. In this paper, the working principles, the merits and demerits of various quantum memory protocols are illustrated. Furthermore, the approaches to eliminating noise and the applications of quantum memory are summarized.