Exploring quantum optics in the terahertz

Ileana-Cristina Benea-Chelmus

Nooshin Parkan, Mohammad Mahmoudi

This paper explores the optical limiting (OL) characteristics of an input probe field within a closed-loop asymmetric coupled quantum well (ACQW) system. Our research reveals that the application of Terahertz (THz) coupling laser fields can induce the OL behavior within the THz domain in the ACQW. The study demonstrates that revers saturable absorption arises through cross-Kerr nonlinearity, contributing to the emergence of OL behavior. Additionally, it is shown that the self-defocusing is induced concurrently within the system, further enhancing nonlinear refractive OL effects. Furthermore, it is revealed that the properties of induced OL can be manipulated by adjusting the characteristics of the applied fields. The discovered outcomes hold potential utility in safeguarding sensors and detectors operating within the THz band.

Ramarao Inguva

Jia Du, Xiang Gao, Ting Zhang +1 more

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.

Daniel F. Walls, Gerard J Milburn

Elena Redchenko, Vladislav Ulitco, Mariia Zhuldybina +3 more

The terahertz (THz) regime of electromagnetic radiation, spanning frequencies from 0.1 to tens of THz, has found widespread use in communication, sensing, quality control, and biomedical applications. Quantum realm of THz domain is, however, still at an earlier development stage and mostly referenced in the context of applied technologies for single-photon generation and detection, with rarer examples of exploration of quantum phenomena. Recent advances in cryogenic hybrid quantum systems suggest that THz radiation may play a pivotal role in emerging quantum technologies. These systems, which require operation at milliKelvin temperatures, offer new opportunities for quantum memory, frequency transduction, and precision measurements, with THz radiation enabling access to molecular vibrational, rotational, and librational transitions. Despite progress in THz components at low temperatures, there remains a critical gap in the systematic integration of THz technologies within sub-Kelvin cryogenic platforms such as dilution refrigerators and adiabatic demagnetization systems. This review presents a comprehensive roadmap for the development of THz photonics in extreme cryogenic environments, addressing implementation strategies, material considerations, waveguide and fiber technologies, and quantum-compatible detection schemes. We further highlight prospective applications in quantum optics, superconductivity, and fundamental physics, aiming to establish THz photonics as a versatile tool for controlling and probing quantum states in sub-Kelvin regimes.