Cavity System Research Articles

Deterministic Photon Storage and Readout in a Semimagnetic Quantum Dot–Cavity System Doped with a Single Mn Ion

AbstractLight trapping is a crucial mechanism for synchronization in optical communication. Especially on the level of single photons, control of the exact emission time is desirable. In this paper, a single‐photon buffering device composed of a quantum dot doped with a single Mn atom in a cavity is theoretically proposed. A method to detain a single cavity photon as an excitation of the dot is presented. The storage scheme is based on bright to dark exciton conversion performed with an off‐resonant external optical field and mediated via a spin‐flip with the magnetic ion. The induced Stark shift brings both exciton states to resonance and results in an excitation transfer to the optically inactive one. The stored photon can be read out on demand in the same manner by repopulating the bright state, which has a short lifetime. The results indicate the possibility to suspend a photon for almost two orders of magnitude longer than the lifetime of the bright exciton.

Plasmon-induced transparency in a reconfigurable composite valley photonic crystal.

We propose a new kind of reconfigurable topological valley photonic crystal (TVPC), and a novel topological waveguide can be formed by constructing a domain wall between two TVPCs with opposite valley-Chern indices. The topological waveguide mode in the composite TVPC has large group refractive index. A topologically protected coupled waveguide cavity system is then designed by introducing a hexagonal ring cavity at the center of the straight domain wall of a combined TVPC, in which a narrow plasmon induced transparency window rises at 3.8848 GHz with a Q-factor of 1387 and a maximum group refractive index as high as 186. We propose a notch filter with a resonant frequency of 3.8852 GHz and a very high Q-factor of 10224. By changing the refractive index of liquid crystals via an external voltage applied between two parallel metal plates, the filter can be switched between band-pass and band-stop based on the reconfigurable topological interface state.

Stability of the Discrete Time-Crystalline Order in Spin-Optomechanical and Open Cavity QED Systems

Discrete time crystals (DTC) have been demonstrated experimentally in several different quantum systems in the past few years. Spin couplings and cavity losses have been shown to play crucial roles for realizing DTC order in open many-body systems out of equilibrium. Recently, it has been proposed that eternal and transient DTC can be present with an open Floquet setup in the thermodynamic limit and in the deep quantum regime with few qubits, respectively. In this work, we consider the effects of spin damping and spin dephasing on the DTC order in spin-optomechanical and open cavity systems in which the spins can be all-to-all coupled. In the thermodynamic limit, it is shown that the existence of dephasing can destroy the coherence of the system and finally lead the system to its trivial steady state. Without dephasing, eternal DTC is displayed in the weak damping regime, which may be destroyed by increasing the all-to-all spin coupling or the spin damping. By contrast, the all-to-all coupling is constructive to the DTC in the moderate damping regime. We also focus on a model which can be experimentally realized by a suspended hexagonal boron nitride (hBN) membrane with a few spin color centers under microwave drive and Floquet magnetic field. Signatures of transient DTC behavior are demonstrated in both weak and moderate dissipation regimes without spin dephasing. Relevant experimental parameters are also discussed for realizing transient DTC order in such an hBN optomechanical system.

Generation of an Enhanced Multi‐Mode Optomechanical‐Like Quantum System and Its Application in Creating Hybrid Entangled States

AbstractRealizing strong optomechanical interaction at a few‐photon level is one of the most significant tasks in optomechanical physics. In this paper, an efficient approach to realize an enhanced optomechanical‐like coupling in a cross‐Kerr‐type coupled three‐mode optical cavity system via a driving field is presented. It is shown that the optomechanical‐like coupling can be strongly enhanced to enter the ultrastrong‐coupling regime, and the effects of cavity field damping can be effectively restrained by adjusting the driving field and the cavity frequencies. In addition, as an application of the enhanced multimode optomechanical‐like quantum system, a scheme is propsed to deterministically generate a hybrid Greenberger–Horne–Zeilinger state. Numerical simulation reveals that the scheme is reliable and robust against various dissipation effects and the fluctuations of control parameters in current technology. This work has potential applications in quantum information processing and paves the way for the study of multimode optomechanical systems.

Strong coupling and active cooling in a finite-temperature hybrid atom-cavity system

For a standard two-level atom coupled to the quantized field of a resonant cavity, finite temperature effects lead to thermal occupation of the cavity modes that obfuscates measurement of the quantum nature of the atom-light interaction. In this paper we demonstrate that using a hybrid system of a superconducting cavity coupled to a multi-level Rydberg atom it is possible to observe the quantum nature of strong coupling even at finite temperatures, and to exploit this coupling to permit cooling of the thermal microwave mode towards the ground-state, enabling observation of coherent vacuum Rabi oscillations even at 4~K for realistic experimental parameters. Cooling for multiple atoms is also explored, showing maximal cooling for small samples, making this a viable approach to cavity cooling with potential applications in long-range coupling of superconducting qubits via thermal waveguides.

The principle of the three-dimensional visual environment of the operating field in rhinosurgery

Traditional endoscopes that create a two-dimensional image cannot provide stereoscopic imagining of the operating field, which does not allow simultaneous synchronization of visual perception with the surgeon's handwork. The operator still achieves in-depth perception through tactile and visual cues, such as the interaction of instruments or the continuous movement of the endoscope. To examine the three-dimensional visual environment for the operating field in endoscopic rhinosinus surgery based on the stereopsis phenomenon. Thanks to multi-spiral computed tomography, we have examined the functional structure features of ram's synonasal region, and described the system of the accessory nasal cavities. We practiced, and compared the techniques of endoscopic rhinosinus surgery using traditional methods versus a three-dimensional visual environment. As a result, we found the advantages of the live surgery in a virtual reality helmet, confirmed by the NASA Task Load Index questionnaire. The use of a virtual reality helmet in rhinosurgery allows the operator to work in a three-dimensional visual environment based on the phenomenon of stereopsis, as a qualitatively improved method of surgical wound videoscopy.

All-colloidal parity-time-symmetric microfiber lasers balanced between the gain of colloidal quantum wells and the loss of colloidal metal nanoparticles.

Lasers based on semiconductor colloidal quantum wells (CQWs) have attracted wide attention, thanks to their facile solution-processability, low threshold and wide range spectral tunability. Colloidal microlasers based on whispering-gallery-mode (WGM) resonators have already been widely demonstrated. However, due to their microscale size typically supporting multiple modes, they suffer from multimode competition and higher threshold. The ability to control the multiplicity of modes oscillating within colloidal laser resonators and achieving single-mode lasers is of fundamental importance in many photonic applications. Here we show that as a unique, simple and versatile architecture of all-colloidal lasers intrinsically enabled by balanced gain/loss segments, the lasing threshold reduction and spectral purification can be readily achieved in a system of a WGM-supported microfiber cavity by harnessing the notions of parity-time symmetry (PT). In particular, we demonstrate a proof-of-concept PT-symmetric microfiber laser employing CQWs as the colloidal gain medium along with a carefully tuned nanocomposite of Ag nanoparticles (Ag NPs) incorporated into a PMMA matrix altogether and conveniently coated around a coreless microfiber as a rigorously tailored colloidal loss medium to balance the gain. The realization of gain/loss segments in our PT-symmetric all-colloidal arrangement is independent of selected pumping, reducing the complexity of the system and making compact device applications feasible, where control over the pumping is not possible. We observed a reduction in the number of modes, resulting in a reduced threshold and enhanced output power of the PT-symmetric laser. The PT-symmetric CQW-WGM microcavity architecture offers new opportunities towards simple implementation of high-performance optical resonators for colloidal lasers.

Chronic Tibial Osteomyelitis - Use of Biactive Glass as an Alternative of Treatment: Report of a Case

<i>Background:</i> Chronic osteomyelitis is a disease usually of infectious origin. The main cause is post-traumatic, it affects the bone tissue and surrounding tissue, the most frequent causative agent is Staphylococcus aureus. The most affected bone is the tibia. <i>Case description:</i> A 42-year-old male with a diagnosis of chronic tibia osteomyelitis, with sequelae of previous surgical interventions, multiple antibiotic treatments, and type IV B classification by Cierny-Mader. <i>Methods:</i> Two-stage surgical management was chosen. Firstly, extensive bone and soft tissue debridement, placement of cement beads medicated with amikacin in the medullary cavity and osteoclast system for irrigation with vancomycin. In the second stage, free fibular bone grafting, fixation and stabilization with screws, bioactive glass placement in areas of interface between stabilized fibula and posterior tibial cortex. <i>Results:</i> Before a multitratada chronic osteomyelitis it is necessary to individualize and evaluate treatment alternatives, in this case the surgical management in two time, the use of medication beads, bone graft and the use of bioactive glass, achieved a complete eradication of the infection and favorable clinical evolution with optimal functional recovery of affected limb.

Aplicação dos óleos ozonizados nos sistemas do corpo humano e cavidade oral

ABSTRACT Wound healing consists of the coordinated cascade of molecular, cellular and biochemical events that interact for tissue recomposition to occur. The interruption or failure in this process can trigger the delay in closing the lesion and chronic wounds, in addition to infections. Ozonotherapy proves to be a promising alternative, capable of assisting in the tissue healing process, modulating the inflammatory response and preventing the development of infection. To present, analyze and discuss, through a literature review, the use of Ozonated Oils in the repair of the human body and oral cavity systems. SciELO, LILACS, MEDLINE and PubMed databases were consulted, using the following DeCS / MeSH descriptors: “ozonized oil”; “healing”; “ozone therapy”. After crossing, counting and analyzing, 13 studies were selected, according to the theme. Due to the complementary theoretical foundation, 44 articles were included, totaling 57 articles used for the present review. Ozonized Oil therapy has beneficial clinical effects, which include antimicrobial, immunostimulating, analgesic, antipoxic, immunoregulatory and antioxidant action. Topical management of ozone has proven effective for the treatment of foot-and-mouth disease, gingivitis, ulcers and dermatitis, contributing to pain relief and healing. Infectious skin diseases, abscesses, allergic skin diseases, scaly erythema, psoriasis and palmoplantar pustulosis are pathological conditions, the treatment of which benefits from the application of Ozonized Oils. Ozonized Oils have been shown to be effective in the treatment of local infections, when in appropriate formulations and in controlled cases, being a promising therapeutic alternative for tissue repair.

Dual-mode surface-enhanced Raman scattering sensors assembled from graphene plasmonic nanoresonator on photoactive SOI

The nanocavity construction of the 3D-graphene combines with the optical cavity system of the SOI to improve the interaction between the incident light and 3D-graphene. These properties enhance electronic interactions, thereon improving chemical/charge transfer effects in heterojunctions.

On the Resonances of Coupled Qubit–Cavity Systems

We consider a system consisting of a qubit and a microwave transmission line that are coupled by a capacitor which, in turn, is modulated sinusoidally. The Unruh effect is the simultaneous production from vacuum of a pair of photons, one in the qubit and the other in the cavity. The dynamical Casimir effect is the production from vacuum of a pair of photons in the cavity. We analyze this qubit–cavity system and show that the system can be viewed as a pair of coupled quantum-mechanical oscillators and that both the Unruh effect and the dynamical Casimir effect are resonances of this coupled oscillator system. For the case where the cavity supports two propagating modes, in addition to the Unruh and dynamical Casimir effect at each of the supported modes, we predict a “paired Casimir effect,” where one photon is emitted in the cavity in each of two allowed modes, at the appropriate driving frequency. We also calculate analytical approximations to the driving frequencies for all three effects.

Characteristics of coherent photon transport in semiconductor waveguide cavity system

Characteristics of coherent photon transport in semiconductor waveguide cavity system

Динамика сокращения чашечно-лоханочной системы в послеоперационном периоде у больных с гидронефрозом

The aim of the research. To evaluate the dynamics of contraction of the pelvicalyceal system in patients operated with congenital hydronephrosis at different periods of the disease. Material and methods. The archival medical records of 350 patients operated on for congenital hydronephrosis within the period of 1990-2020 were processed. The age of patients at the time of surgery varied from two months to 18 years. Based on the protocols of ultrasound examination of kidneys before and after surgery, the dynamics of contraction of the cavitary system of the operated kidney was evaluated. Results. As a result of surgical intervention, all patients showed reduction in the pelvicalyceal system. The most favourable result of cavitary system reduction after surgery was obtained in the 1st age group: 75.24% of the pelvis and 77.76% of the calyx; a low percentage was diagnosed in the 7th age group with 41.39% and 43.38%, respectively. Conclusion. In patients operated under the age of six months, a statistically significant better result regarding the contractility of the renal cavity system was obtained. With increasing age at the time of surgery, the elasticity of the pelvicalyceal system gradually decreases.

Experimental investigation of light-matter interaction when transitioning from cavity QED to waveguide QED

Cavity quantum electrodynamics (cavity QED) is conventionally described by the Jaynes- or Tavis-Cummings model, where quantum emitters couple to a single-mode cavity. The opposite scenario, in which an ensemble of emitters couples to a single spatial mode of a propagating light field, is described by waveguide QED, where emitters interact with a continuum of frequency modes. Here we present an experiment where an ensemble of cold atoms strongly couples to a fiber-ring resonator with variable length containing an optical nanofiber. By changing the length of the resonator we can tailor the density of frequency modes and thus explore the transition from cavity QED to waveguide QED. We analyse the response of the ensemble–cavity system after the sudden switch-on of resonant laser light and find that for progressively longer resonators, the Rabi oscillations typical of cavity QED disappear and the single-pass dynamics of waveguide QED appear. Our measurements shed light on the interplay between the single-pass collective response of the atoms to the propagating cavity field and the ensemble–cavity dynamics.

Hybrid modelling of cavity system generated electromagnetic pulse in low pressure air

The surface of metal system exposed to ionizing radiation (X-ray and γ-ray) will emit high-energy electrons through the photoelectric effect and other processes. The transient electromagnetic field generated by the high-speed electron flow is called system generated electromagnetic pulse (SGEMP), which is difficult to shield effectively. An ongoing effort has been made to investigate the SGEMP response in vacuum by numerical simulation. However, the systems are usually operated in a gaseous environment. The objective of this paper is to investigate the effect of low-pressure air on the SGEMP. A three-dimensional hybrid simulation model is developed to calculate the characteristics of the electron beam induced air plasma and its interaction with the electromagnetic field. In the hybrid model, the high-energy photoelectrons are modelled as macroparticles, and secondary electrons are treaed as fluid for a balance between efficiency and accuracy. A cylindrical cavity with an inner diameter of 100 mm and a length of 50 mm is used. The photoelectrons are emitted from one end of the cavity and are assumed to be monoenergetic (20 keV). The photoelectron pulse follows a sine-squared distribution with a peak current density of 10 A/cm&lt;sup&gt;2&lt;/sup&gt;, and its full width at half maximum is 2 ns. The results show that the number density of the secondary electrons near the photoelectron emission surface and its axial gradient increase as air pressure increases. The electron number density in the middle of the cavity shows a peak value at 20 Torr (1 Torr = 133 Pa). The electron temperature decreases monotonically with the increase in pressure. The low-pressure air plasma in the cavity prevents the space charge layer from being generated. The peak value of the electric field is an order of magnitude lower than that in vacuum, and the pulse width is also significantly reduced. The emission characteristic of the photoelectrons determines the peak value of the current response. The current reaching the end of the cavity surface first increases and then decreases with pressure increasing. The plasma return current can suppress the rising rate of the total current and extend the duration of current responses. Finally, to validate the established hybrid simulation model, the calculated magnetic field is compared with that from the benchmark experiments. This paper helps to achieve a better prediction of the SGEMP response in a gaseous environment. Compared with the particle-in-cell Monte Carlo collision method, the hybrid model adopted can greatly reduce the computational cost.

Plasmon induced transparency effect based on graphene nanoribbon waveguide side-coupled with rectangle cavities system

In order to reduce the size of the device and realize the ultrafast response time and dynamic tunableness, the single-band and dual-band plasmon induced transparency (PIT) effect are investigated based on graphene nanoribbon waveguide side-coupled rectangle cavity. The slow light properties of the model are analyzed numerically and theoretically by coupled mode theory and finite difference time domain method. With controlling the chemical potential of the graphene rectangle cavity, the tunability of the resonant wavelength and the transmission peak can be achieved simultaneously in single-band and dual-band PIT model. As the chemical potential of graphene increases, the resonant wavelength of each transmission window of PIT effect decreases gradually and presents the blue shift. In addition, through dynamically tuning the resonant wavelength of the graphene rectangle cavity, when the chemical potential of the graphene rectangle cavity increases from 0.41 to 0.44 eV, the group index of single PIT system is controlled to be between 79.2 and 28.3, and the tunable bandwidth is 477 nm. Moreover, the group index of dual PIT system is controlled to be between 143.2 and 108.6 when the chemical potentials of graphene rectangle cavities 1, 2, and 3 are 0.39–0.42 eV, 0.40–0.43 eV, and 0.41–0.44 eV, respectively. The size of the entire PIT structure is &lt;0.5 μm&lt;sup&gt;2&lt;/sup&gt;. The research results here in this work are of reference significance in designing and fabricating the optical sensors, optical filters, slow light and light storage devices with ultrafast, ultracompact and dynamic tunableness.

Assessment of the state of health of teachers of secondary schools

Introduction. Among the leading risk factors affecting the teaching contingent in their labour activity, psychoemotional stress, load on the vocal apparatus, hypodynamia, and prolonged forced posture are distinguished. As a result of hypodynamia - there is a violation of blood circulation, deterioration of the venous and lymphatic systems and further development of arterial hypertension (AH), overweight, varicose veins (VV), a decrease in the body’s immune forces, leading to frequent colds and chronic pathology of ENT organs. Therefore, the study of the health status of teachers, the prevention of diseases is an urgent task today. The purpose of the study is to assess the health status of teachers in general education schools based on many clinical and ultrasound examinations. Materials and methods. The object of the research was 78 teachers of secondary schools. All subjects were females, with an average age of 53.4 ± 8.3 years, an average work experience of 32.1 ± 9.1 years. Clinical and ultrasound examinations were carried out. Results. During clinical examination by narrow specialists, the detection of ENT organ pathology in the study group per 100 examined patients was 52 cases (66.6 ± 6.5%), 89 (114.1 ± 4.3%) cases - therapeutic pathology (among which arterial hypertension prevailed), 56 (71.8 ± 6.1%) cases of the endocrine system and 72 (92.3 ± 3.2%) cases of diseases of the nervous system. The frequency of pathological changes in the abdominal cavity and urinary system during screening ultrasound was 86% of cases, the thyroid gland - 70.0 ± 1.0% of cases. Conclusion. A clinical examination of the health status of teachers with more than ten years of experience has established one of the first places to be occupied by therapeutic pathology, in the form of CVS diseases, in the second place are diseases of the nervous system (vertebral pathology), the third-place belongs to diseases of the ENT organs and the endocrine system.

Enhancing high frequency sensitivity of gravitational wave detectors with a Sagnac interferometer

The sensitivity of gravitational-wave detectors is limited in the high-frequency band by quantum shot noise and eventually limited by the optical loss in the signal recycling cavity. This limit is the main obstacle to detecting gravitational waves from binary neutron star mergers in the current and future-generation detectors, as it does not depend on either the arm length in the high-frequency band or the injected squeezing level. In this paper, we present the sloshing-Sagnac interferometer topology, which can be obtained from the Michelson interferometer by optically connecting the end mirrors into an additional optical cavity. This transforms the interferometer into a triply coupled cavity system capable of beating the loss-induced high-frequency limit of the signal-recycled Michelson interferometer. With the upgrade plan of Advanced LIGO, A+ comparable parameters, a sloshing-Sagnac scheme can achieve 7 times better sensitivity at 2.5 kHz or a 4 times better signal-to-noise ratio for a typical waveform of binary neutron star post merge. Being an evolution of a Michelson interferometer, the sloshing-Sagnac interferometer can possibly be used as a topology for the future-generation detectors and upgrades of current detectors.

Topological cascaded coupled cavities system: Neo-analysis of temporal coupled-mode theory

<p indent="0mm">In recent years, it has been discovered that topological photonics can ensure the robust optical behaviors of multiple optical devices, which eases the impact of defects and other perturbations on the device performance. Therefore, the combination of topological photonics and filter design is on demand. Recently, the transmission efficiency equation in a four-terminal cascaded coupled cavities system was derived based on the temporal coupled-mode theory. And general high-order nonreciprocals add/drop filter structure was designed. The simulation results are in good agreement with the theoretical prediction.

Effects of Removal Conditions on Mercury Amount Remaining in the Oral Cavity and inside Drainage System after Removing Dental Amalgams.

Mercury is produced and drained into the environment by removing dental amalgams, which may cause mercury pollution. This study aimed to clarify the mercury amount remaining in the oral cavity and inside the drain system after removal. The effects of the removal conditions and differences in drainage systems were also investigated. Dental amalgams filled in the tooth and placed in a phantom head were removed using an air turbine under several conditions (two removal methods, absence of cooling water, and intraoral suction). Then, the oral cavity was rinsed with 100 mL of water (oral rinse water), and 500 mL of water was suctioned to wash the inside of the drainage system (system rinse water). Both water samples were collected in two ways (amalgam separator and gas-liquid separator), and their mercury amounts were measured. It was found that the amount of mercury left in the oral cavity and drainage system after dental amalgams removal could be reduced when the amalgams were removed by being cut into fragments as well as using cooling water and intraoral suction. In addition, using amalgam separators can significantly reduce the amount of mercury in the discharge water and prevent the draining of mercury into the environment.