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Quantum electronics operating in the microwave domain are burgeoning and becoming essential building blocks of quantum computers, sensors, and communication devices. However, the field of microwave quantum electronics has long been dominated by the need for cryogenic conditions to maintain delicate quantum characteristics. Here, a solid‐state hybrid system, constituted by a photo‐excited pentacene triplet spin ensemble coupled to a dielectric resonator, is reported for the first time capable of both coherent microwave quantum amplification and oscillation at X band via the masing process at room temperature. By incorporating external driving and active dissipation control into the hybrid system, efficient tuning of the maser emission characteristics at ≈9.4 GHz is achieved, which is key to optimizing the performance of the maser device. The work not only pushes the boundaries of the operating frequency and functionality of the existing pentacene masers but also demonstrates a universal route for controlling the masing process at room temperature, highlighting opportunities for optimizing emerging solid‐state masers for quantum information processing and communication. [ABSTRACT FROM AUTHOR]

Steady-state superradiance and superradiant lasing attract significant attentions in the field of optical lattice clocks, but have not been achieved yet due to the technical challenges and atom loss problem. In this article, we propose that their counter-part may be observed in the microwave domain with solid-state spins, i.e., nitrogen-vacancy center spins and pentacene molecular spins, coupled to microwave resonator at room temperature with realistic technical restrictions. To validate our proposal, we investigate systematically the system dynamics and steady-state by solving quantum master equations for the multi-level and multi-process dynamics of trillions of spins. Our calculations show that the superradiant Rabi oscillations occur firstly due to transitions among different Dicke states, and the subsequent continuous-wave superradiant masing can achieve a linewidth well below millihertz. Our work may guide further exploration of transient and steady-state superradiant masing with the mentioned and other solid-state spins systems. The ultra-narrow linewidth may find applications in deep-space communications, radio astronomy and high-precision metrology. [ABSTRACT FROM AUTHOR]

Abstract Quantum electronics operating in the microwave domain are burgeoning and becoming essential building blocks of quantum computers, sensors, and communication devices. However, the field of microwave quantum electronics has long been dominated by the need for cryogenic conditions to maintain delicate quantum characteristics. Here, a solid‐state hybrid system, constituted by a photo‐excited pentacene triplet spin ensemble coupled to a dielectric resonator, is reported for the first time capable of both coherent microwave quantum amplification and oscillation at X band via the masing process at room temperature. By incorporating external driving and active dissipation control into the hybrid system, efficient tuning of the maser emission characteristics at ≈9.4 GHz is achieved, which is key to optimizing the performance of the maser device. The work not only pushes the boundaries of the operating frequency and functionality of the existing pentacene masers but also demonstrates a universal route for controlling the masing process at room temperature, highlighting opportunities for optimizing emerging solid‐state masers for quantum information processing and communication.

Axions can be stimulated to decay into photons by ambient photons of the right frequency or by photons from the decay of neighboring axions. If the axion density is high enough, the photon intensity can be amplified, which is a type of lasing or an axion maser. Here, we review the astrophysical situations where axion lasing can appear and possibly be detected. [ABSTRACT FROM AUTHOR]

Research articles in all branches of modern science are crowded with the abbreviated technical terms known as acronyms, a phenomenon that was essentially unknown before World War II. Apart from an introduction to the notion of acronyms and its short history, the paper discusses from a historical perspective the connections between acronyms and eponyms in science. Moreover, it charts how acronyms and abbreviations became so common in physics and astronomy that the excessive use of them came to be considered a symptom of a contagious disease. While many science acronyms are exotic and little used, and some downright bizarre, others have become household words that in some cases are not even recognized to be acronymic constructions. The paper briefly examines the naming histories of some of these successful acronyms in physics and astronomy, among them radar, sonar, maser, laser, and pulsar. [ABSTRACT FROM AUTHOR]

Coherent sources exploiting the stimulated emission of non‐equilibrium quantum systems, i.e., gain media, have proven indispensable for advancing fundamental research and engineering. The operating electromagnetic bands of such coherent sources have been continuously enriched for increasing demands. Nevertheless, simultaneous generation of radiation in multiple widely‐separated bands presents formidable challenges with a single gain medium. Herein, a mechanism of simultaneously realizing the stimulated emission of radiation in the visible and microwave bands, i.e., lasing and masing actions, at ambient conditions by utilizing photoexcited singlet and triplet states of pentacene doped in p‐terphenyl is proposed. The possibility is validated by the observed amplified spontaneous emission (ASE) at 645 nm with a narrow linewidth around 1 nm from the pentacene‐doped p‐terphenyl crystal used for masing at 1.45 GHz and consolidated by a 20‐fold‐lower threshold of ASE compared to the reported masing threshold. The overall threshold of the pentacene‐based multiband coherent source can be optimized by appropriate alignment of the pump‐light polarization with the pentacene's transition dipole moment. This work not only shows a great promise on immediate realization of multiband coherent sources but also establishes an intriguing solid‐state platform for fundamental research of quantum optics in multiple frequency domains. [ABSTRACT FROM AUTHOR]

The hosts of OH megamaser (OHM) are luminous infrared galaxies (LIRGs), in fact 1/3 of them are ultra-luminous infrared galaxies (ULIRGs), which imply that OHM phenomena should be related to the infrared radiation field. In this paper, we investigate the far infrared (FIR) properties of OHM host galaxies, through detailed infrared data covering broad bands. All known OHM sources and one control sample of (U)LIRGs without maser detections (non-OHM sources) are cross-identified with AKARI and Herschel photometric catalogs. Comparative analysis on the spectral energy distribution (SED) with broad coverage from J to 350 μ m (taken from 2MASS, WISE, Spitzer, and AKARI and Herschel archive data) shows that the OHM sources tend to have higher FIR luminosities than those of the non-OHM sources, which are more pronounced in the SED range covered by the AKARI. These are consistent with our statistical results of the FIR luminosities distribution of both the samples, which show that the OHM sources tend to have higher FIR luminosities, especially, at short FIR wavelength (i.e., the 65 and 90 μ m). However, the non-OHM sources tend to have much stronger emission than those of OHM sources at both the near infrared (NIR) and middle infrared (MIR) bands. The statistic analysis of the color–color properties at MIR and FIR bands shows that the OHM sources have much cooler MIR and warmer FIR colors than non-OHM sources. These clues could help us to choose OHM candidates for future OHM surveys with the Five-hundred-meter Aperture Spherical radio Telescope (FAST), where the OHM detection rate may exceed 40%. Further, one significant correlation of L OH ∝ L T FIR 1.18 ± 0.11 can be found between the maser luminosity and total FIR luminosity of OHM LIRGs. Combined with previous studies, we suggest that the OHM is dominantly pumped by the FIR, instead of NIR and MIR radiation fields. [ABSTRACT FROM AUTHOR]

Axions can be stimulated to decay into photons by ambient photons of the right frequency or by photons from the decay of neighboring axions. If the axion density is high enough, the photon intensity can be amplified, which is a type of lasing or an axion maser. Here, we review the astrophysical situations where axion lasing can appear and possibly be detected.

VERA has been regularly conducting astrometry of Galactic maser sources for ∼ 20 years, producing more than 100 measurements of parallaxes and proper motions of star-forming regions as well as AGB stars. By combining the observational results obtained by VLBA BeSSeL, EVN, and LBA, maser astrometry provides a unique opportunity to explore the fundamental structure of the Galaxy. Here we present the view of the Galaxy revealed by the maser astrometry, and also discuss the importance of maser astrometry in the era of GAIA by comparing the results obtained by VLBI and GAIA. We also present our view of "proper motions toward the future" of the relevant field, expected in the next decade based on global collaborations. [ABSTRACT FROM AUTHOR]

We present the first results of simultaneous observations of the 6.035 GHz exited OH and 6.7 GHz methanol masers toward a sample of 10 high-mass young stellar objects (HMYSOs), observed using eMERLIN in 2020 and 2022. Searching for the coincidence and avoidance of these two maser transitions, we estimate physical conditions around central protostars. We identify Zeeman-splittings of the OH emission and determine the strength of the magnetic field. Combining it with linear polarization, we derive the magnetic field structure in these high-mass star-forming regions. [ABSTRACT FROM AUTHOR]

From the various aspects of spintronics the review highlights the area devoted to the creation of new functional materials based on magnetic semiconductors and demonstrates both the main physical phenomena involved and the technical possibilities of creating various devices: maser, p-n diode with colossal magnetoresistance, spin valve, magnetic lens, optical modulators, spin wave amplifier, etc. Particular attention is paid to promising research directions such as ultrafast spin transport and THz spectroscopy of magnetic semiconductors. Special care has been taken to include a brief theoretical background and experimental results for the new spintronics approach employing magnetostrictive semiconductors—strain-magnetooptics. Finally, it presents top-down approaches for magnetic semiconductors. The mechano-physical methods of obtaining and features of the physical properties of high-density nanoceramics based on complex magnetic oxides are considered. The potential possibility of using these nanoceramics as an absorber of solar energy, as well as in modulators of electromagnetic radiation, is shown. [ABSTRACT FROM AUTHOR]

Due to isolation from the environment with the protection of the full electronic shells, nuclear spins of noble gas typically feature extraordinary long coherence times, high polarization and good chemical inertness, which makes themselves attractive in extensive scientific applications. Recently, the noble-gas spin amplification via the spin-exchange collisions between overlapping noble-gas spins and alkali-atom spins has been theoretically and experimentally demonstrated in various quantum techniques including maser, Floquet maser, spin-based amplifier, and Floquet spin amplifier. The noble-gas spin amplification can enhance the external oscillating magnetic field by a factor of more than 100 and realize ultrasensitive magnetometry, which is important for the detection of weak electromagnetic fields and hypothetical particles. Based on the spin amplification, experiments have been conducted to search for axion-like dark matter and exotic spin-dependent forces and new constraints have been established. This review summarizes the recent progress on noble-gas spin amplification, including the basic principles, methods, different types, the related applications ranging from magnetic-field sensing to searches for new physics, and prospects for further improvements. [ABSTRACT FROM AUTHOR]

Masers as telecommunication amplifiers have been known for decades, yet their application is strongly limited due to extreme operating conditions requiring vacuum techniques and cryogenic temperatures. Recently, a new generation of masers has been invented based on optically pumped spin states in pentacene and diamond. In this study, we pave the way for masers based on spin S = 3/2 silicon vacancy (VSi) defects in silicon carbide (SiC) to overcome the microwave generation threshold and discuss the advantages of this highly developed spin hosting material. To achieve population inversion, we optically pump the VSi into their mS = ±1/2 spin sub-states and additionally tune the Zeeman energy splitting by applying an external magnetic field. In this way, the prerequisites for stimulated emission by means of resonant microwaves in the 10 GHz range are fulfilled. On the way to realising a maser, we were able to systematically solve a series of subtasks that improved the underlying relevant physical parameters of the SiC samples. Among others, we investigated the pump efficiency as a function of the optical excitation wavelength and the angle between the magnetic field and the defect symmetry axis in order to boost the population inversion factor, a key figure of merit for the targeted microwave oscillator. Furthermore, we developed a high-Q sapphire microwave resonator (Q = 104-105) with which we find superradiant stimulated microwave emission. In summary, SiC with optimized spin defect density and thus spin relaxation rates is well on its way of becoming a suitable maser gain material with wide-ranging applications. [ABSTRACT FROM AUTHOR]

The Central Molecular Zone (CMZ) makes up roughly the inner 500 pc of the Milky Way and has a large amount of dense hot gas, strong magnetic fields, and highly energetic particles. The Survey of Water and Ammonia in the Galactic Center (SWAG) is a major imaging line survey using the Australia Telescope Compact Array with the goal to map out the molecular content in the entire CMZ. SWAG data includes the 22 GHz H2O maser transition which is typically used as a tracer for phases of star formation, including both young stellar objects (YSOs) and evolved stars, such as asymptotic giant branch (AGB) stars. The SWAG H2O survey is significantly deeper with better resolution than existing surveys that cover the entire CMZ. The goal is to create a robust catalog of the maser positions, spectral properties, and the sources they trace. The H2O maser catalog shows 703 H2O masers which increases the amount of detected H2O masers in the CMZ by more than an order of magnitude. The H2O masers have a more symmetric distribution in the Galactic center than that of the gas. Cross-correlation with other observations and catalogs will provide information relating maser properties to YSOs and AGB stars, for which multiple maser components will provide outflow properties. We will also connect the surrounding molecular gas to the YSO maser velocities. [ABSTRACT FROM AUTHOR]

Recent experiments have demonstrated Rabi-oscillations, superradiant pulses and stimulated emission from negatively-charged nitrogen-vacancy (NV−) center spins in microwave resonators. These phenomena witness the kind of collective and strong coupling which has been the prerequisite for observation of superradiant lasing in the optical frequency regime. In this article, we investigate the possibility to employ coherence, present in both the collective NV− spin ensemble and the microwave field, to achieve a superradiant maser. Our calculations show that a superradiant maser with a linewidth below millihertz can be achieved with moderate kilohertz incoherent pumping of over 1014 spins at room temperature. We show that the superradiant masing prevails in the presence of inhomogeneous broadening, and we present numerical and analytical studies of the dependence of the phenomenon on the various physical parameters. [ABSTRACT FROM AUTHOR]

At the height of the Cold War, in the 1950s, the process of parallel invention of masers and lasers took place on the opposing sides of the Iron Curtain. While the American part of the story has been investigated by historians in much penetrating detail, comparable Soviet developments were described more superficially. This study aims at, to some extent, repairing this discrepancy by analyzing the Soviet path towards the maser from a comparative angle. It identifies, on the one hand, significant differences between the two projects regarding their heuristics, the relationship between theory and experiment, grounding in different academic cultures, and the resulting conceptualization of the maser principle. At the same time, the case also illustrates more fundamental transformations in the practices of postwar research that can be characterized as a convergence between the Soviet and the American science of the period. [ABSTRACT FROM AUTHOR]

Heat engines, which cyclically transform heat into work, are ubiquitous in technology. Lasers and masers may be viewed as heat engines that rely on population inversion or coherence in the active medium. Here we put forward an unconventional paradigm of a remarkably simple and robust electromagnetic heat-powered engine that bears basic differences to any known maser or laser: The proposed device makes use of only one Raman transition and does not rely on population inversion or coherence in its two-level working medium. Nor does it require any coherent driving. The engine can be powered by the ambient temperature difference between the sky and the ground surface. Its autonomous character and "free" power source make this engine conceptually and technologically enticing. [ABSTRACT FROM AUTHOR]

The Winter Colloquium on the Physics of Quantum Electronics (PQE) has been a seminal force in quantum optics and related areas since 1971. It is rather mind-boggling to recognize how the concepts presented at these conferences have transformed scientific understanding and human society. In January 2017, the participants of PQE were asked to consider the equally important prospects for the future, and to formulate a set of questions representing some of the greatest aspirations in this broad field. The result is this multi-authored paper, in which many of the world’s leading experts address the following fundamental questions: (1) What is the future of gravitational wave astronomy? (2) Are there new quantum phases of matter away from equilibrium that can be found and exploited - such as the time crystal? (3) Quantum theory in uncharted territory: What can we learn? (4) What are the ultimate limits for laser photon energies? (5) What are the ultimate limits to temporal, spatial and optical resolution? (6) What novel roles will atoms play in technology? (7) What applications lie ahead for nitrogen-vacancy centres in diamond? (8) What is the future of quantum coherence, squeezing and entanglement for enhanced super-resolution and sensing? (9) How can we solve (some of) humanity’s biggest problems through new quantum technologies? (10) What new understanding of materials and biological molecules will result from their dynamical characterization with free-electron lasers? (11) What new technologies and fundamental discoveries might quantum optics achieve by the end of this century? (12) What novel topological structures can be created and employed in quantum optics? [ABSTRACT FROM AUTHOR]

Abstract: To understand the mystery of life, it is important to accumulate genomic information for various organisms because the whole genome encodes the commands for all the genes. Since the genome of Strongylocentrotus purpratus was sequenced in 2006 as the first sequenced genome in echinoderms, the genomic resources of other North American sea urchins have gradually been accumulated, but no sea urchin genomes are available in other areas, where many scientists have used the local species and reported important results. In this manuscript, we report a draft genome of the sea urchin Hemincentrotus pulcherrimus because this species has a long history as the target of developmental and cell biology in East Asia. The genome of H. pulcherrimus was assembled into 16,251 scaffold sequences with an N50 length of 143 kbp, and approximately 25,000 genes were identified in the genome. The size of the genome and the sequencing coverage were estimated to be approximately 800 Mbp and 100×, respectively. To provide these data and information of annotation, we constructed a database, HpBase ( http://cell-innovation.nig.ac.jp/Hpul/). In HpBase, gene searches, genome browsing, and blast searches are available. In addition, HpBase includes the “recipes” for experiments from each lab using H. pulcherrimus. These recipes will continue to be updated according to the circumstances of individual scientists and can be powerful tools for experimental biologists and for the community. HpBase is a suitable dataset for evolutionary, developmental, and cell biologists to compare H. pulcherrimus genomic information with that of other species and to isolate gene information. [ABSTRACT FROM AUTHOR]

Theoretical and numerical analyses are presented concerning the conditions at whichthe charged particles of different masses can be accelerated to significant kinetic energy in the circularlypolarized laser or maser beams and a static magnetic field. The studies are carried out usingthe analytical derivations of the particles dynamics and theirs kinetic energy. The presented illustrationsenabled interpretation of the complex motion of particles and the possibilities of their acceleration.At the examples of an electron, proton and deuteron, the velocity, kinetic energy and trajectoryas a function of the acceleration time at the resonance condition are illustrated in the appropriategraphs. The particles with larger masses require the application of enhanced magnetic field intensityat the resonance condition. However, this field intensity can be significantly reduced if the particlesare preaccelerated.[b]Keywords[/b]: optoelectronics, acceleration of charged particles, laser, maser, relativistic dynamics, kineticenergy of a particle, electron, proton, deuteron

The paper briefly describes the history of formation of a new science direction - quantum electronics, associated with the discovery of masers and lasers by scientists from the USA (Ch. Townes) and the USSR (N.G. Basov and A. M. Prokhorov). The world's first ruby laser designed by T. Maiman is described. Some historical events devoted to creation and research of lasers are given in which the author of the paper as well as research workers from Vavilov State Optical Institute, ITMO University and LOMO have taken direct part in the development of solid-state and gas lasers (helium-neon, photodissociation, CO2-lasers) and laser optical systems. Contribution of researchers from Vavilov State Optical Institute, LOMO and ITMO University to large-scale programs on development of lasers for laser nuclear fusion, laser weapons and “Phobos” program is shown. The paper deals in brief with new issues of development and application of lasers, mainly, within the project of laser orbital space station of the future, for the conversion of solar energy into laser radiation. Description of idea of solar energy transformation by fullerene-oxygen laser is presented. The patent for it has been taken out by Vavilov State Optical Institute. Developed fullerene-oxygen-iodine laser and laser structure models for industrial applications and solar energy conversion into laser radiation are described. Parameters for hypothetical laser-optical system of the future space station are given.