Since entering 2000, with the wireless applications and technologies great fast increase, the need for spectral resource is much huge. It is becoming key point that the wireless frequency steps toward higher terahertz frequency band in the academic research aspect. The paper conducts a comparison and discussion on the properties of THz frequency band with other band; Then analyzes the essential conditions on construction quantum transmission system; Afterward, concentrates on the important devices techniques analysis for the emission and detection aspects in THz system; Later, provides the relative experimental development progress; At last, summaries a main technique and application trend of quantum transmission in coming year. All of these studies have useful academic reference value and application significance in the quantum communication field to the specialists later research.
Since entering 2000, with the wireless applications and technologies great fast increase, the need for spectral resource is much huge. It is becoming key point that the wireless frequency steps toward higher terahertz frequency band in the academic research aspect. The paper conducts a comparison and discussion on the properties of THz frequency band with other band; Then analyzes the essential conditions on construction quantum transmission system; Afterward, concentrates on the important devices techniques analysis for the emission and detection aspects in THz system; Later, provides the relative experimental development progress; At last, summaries a main technique and application trend of quantum transmission in coming year. All of these studies have useful academic reference value and application significance in the quantum communication field to the specialists later research.
Abstract Terahertz (THz) technology is a rapidly developing field that explores the use of electromagnetic waves in the THz frequency range. The unique properties of THz waves have great application prospects in electromagnetic sensing, security inspection, non-destructive testing, medical diagnostics, biology, high-speed wireless communication, space science and so on. At present, the application of THz technology is still under continuous research and development, and its broad scientific prospects are recognized worldwide. THz frequency falls into the gap on the electromagnetic spectrum of electronics and optics, thus both classic microwave and optical technologies cannot be directly applied to the THz systems. New components, circuits and application systems are being developed for THz technology. Superconductivity is a quantum mechanical phenomenon and offers unique advantages for applications in high-frequency electromagnetic domains. Novel superconducting quantum devices are being exploited for THz wave radiation and detection, and many THz application systems. The high-T c superconducting (HTS) electronic devices have great potential in emerging THz technologies due to its very high-energy bandgap (well into THz regions) and much relaxed cooling requirement, and they offer strong prospect for the development of practical and portable THz systems. This paper provides an overview of the state-of-art development of HTS THz quantum devices and their application for THz sensing, imaging and communication. The review will start with a brief introduction about cutting-edge THz technology, the fundamental of superconductivity, Josephson effects and the HTS Josephson junctions. Then, the research progress and the latest achievement of HTS Josephson THz emitters, detectors and mixers will be reviewed, followed by their application examples in some THz systems. Finally, the conclusion, challenges and outlooks of the HTS technologies in THz applications are discussed.
With the fast development of Quantum Computers and a better understanding of the quantum realm, Quantum Communications (QC) promises to be one of the main research areas of the upcoming decade. Over the last several years, tremendous effort and progress have already been made in this sense, but until now, QC have primarily been considered at optical frequencies, namely the Near-Infrared (NIR) and visible regions (60-800 THz). This thesis proposes, for the first time, the realization of QC in the terahertz (THz) band (0.1-10 THz), which is expected to become one of the most used bands in the near- immediate future. During the analysis, different possible implementations are considered and discussed. Also, the shape a THz Wireless Quantum channel would take and the main challenges this channel would impose are thoroughly analyzed, considering the wireless channel usually used in quantum optical systems. This thesis is aimed at setting a bench- mark to address the unexplored topic of THz Quantum Communications, enabling future researchers to enter this field and making their work easier.
Abstract Quantum key distribution (QKD) is one of the major applications of quantum information technology. It can provide ultra‐secure key distribution with security guaranteed by the laws of quantum physics. Quantum key distribution is necessary to protect data transmission from quantum computing attacks in future communication networks. The laws of quantum mechanics dictate that as opposed to microwave frequencies, quantum coherence is preserved at room temperatures for terahertz (THz) frequencies. This makes the THz band a promising solution for room‐temperature QKD implementation in future wireless communication networks. The authors present the principles of continuous variable QKD (CV‐QKD) systems and review the latest developments in the design and analysis of CV‐QKD systems operating at microwave and THz frequencies. The authors also discuss how multiple‐input multiple‐output transmission can be incorporated into the quantum communications framework to improve the secret key rates and increase the coverage distances of the THz CV‐QKD system. Furthermore, major hardware challenges that must be surmounted to practically realise THz CV‐QKD systems are highlighted.
Quantum communication is an emerging interdisciplinary discipline that combines classical telecommunication and quantum mechanics. This paper discusses the recent progress of quantum communication in terms of the basic theoretical framework of quantum communication technology, optical devices, state-of-the-art applications. Based on the analysis, quantum communication technology research hotspots mainly involve quantum key distribution, quantum confidential communication, quantum invisible transmission, quantum entanglement, quantum cryptography, etc., which exhibits an increasingly rich trend. In addition, the limitations of the quantum communication are demonstrated from the perspective of practical applications. Afterwards, the future prospects of quantum communication technology are proposed accordingly. These results reveal that quantum communication applications are promising and are moving toward practicality.
With the successful launch of quantum communication satellite, the boom of wireless quantum research and application is rising all over the world, and the security of quantum communication has reached a new height in battlefield communication, but from an objective point of view, this is a misunderstanding of it. Based on this, this paper analyzes the structure of the quantum communication system, and on this basis, makes necessary distinctions between the security, effectiveness and reliability of the communication system. It points out that eavesdropping can still be realized by utilizing the defects of the wireless quantum communication engineering, especially the suppression and interference of wireless quantum communication transmission can greatly affect the effectiveness of communication. Finally, the electronic countermeasures method of wireless quantum communication is summarized through research, which has important reference significance for promoting the application and expansion of quantum countermeasures in electronic countermeasures.
A well-known empirical rule for the demand of wireless communication systems is that of Edholm's law of bandwidth. It states that the demand for bandwidth in wireless short-range communications doubles every 18 months. With the growing demand for bandwidth and the decreasing cell size of wireless systems, terahertz (THz) communication systems are expected to become increasingly important in modern day applications. With this expectation comes the need for protecting users' privacy and security in the best way possible. With that in mind, we show that quantum key distribution can operate in the THz regime and we derive the relevant secret key rates against realistic collective attacks. In the extended THz range (from 0.1 to 50 THz), we find that below 1 THz, the main detrimental factor is thermal noise, while at higher frequencies it is atmospheric absorption. Our results show that high-rate THz quantum cryptography is possible over distances varying from a few meters using direct reconciliation, to about 220m via reverse reconciliation. We also give a specific example of the physical hardware and architecture that could be used to realize our THz quantum key distribution scheme.