Cavity System Research Articles

Universal Quantum Optimization with Cold Atoms in an Optical Cavity.

Cold atoms in an optical cavity have been widely used for quantum simulations of many-body physics, where the quantum control capability has been advancing rapidly in recent years. Here, we show the atom cavity system is universal for quantum optimization with arbitrary connectivity. We consider a single-mode cavity and develop a Raman coupling scheme by which the engineered quantum Hamiltonian for atoms directly encodes number partition problems. The programmability is introduced by placing the atoms at different positions in the cavity with optical tweezers. The number partition problem solution is encoded in the ground state of atomic qubits coupled through a photonic cavity mode, which can be reached by adiabatic quantum computing. We construct an explicit mapping for the 3-SAT and vertex cover problems to be efficiently encoded by the cavity system, which costs linear overhead in the number of atomic qubits. The atom cavity encoding is further extended to quadratic unconstrained binary optimization problems. The encoding protocol is optimal in the cost of atom number scaling with the number of binary degrees of freedom of the computation problem. Our theory implies the atom cavity system is a promising quantum optimization platform searching for practical quantum advantage.

Sodium-doped InP/ZnSeS/ZnS quantum dots as a saturable absorber for passive Q-switched fiber lasers

In this work, sodium-doped InP/ZnSeS/ZnS (InP–Na) QDs was fabricated by thermal injection method for the first time. The nonlinear optical properties were first demonstrated by realizing a modulation depth of 7.85% and saturable intensity of 2.2 MW cm−2 by two-detector method. The Q-switching operations were carried out by integrating InP–Na QDs as saturable absorber (SA) in a fiber laser ring cavity system. Q-switched laser pulses with a pulse width of 139 ns were generated. The ability of effective pulse width compression can be attributed to the short exciton recovery time of SA, as confirmed by transient absorption and time-resolved photoluminescence. This is the first demonstration of Na-doped InP/ZnSeS/ZnS QDs and using it as SA for generating ultrafast laser pulses. Therefore, this study extends the research scope of InP-based QDs in optical communications, nonlinear photonics and ultrafast photonics.

Multiple transparency windows in an atom-assisted Laguerre–Gaussian rovibrational cavity

An atom-assisted Laguerre–Gaussian rovibrational cavity is proposed to demonstrate the characteristics of the output probe field. The cavity comprises a fixed and moving mirror with a two-level qubit inside it, and the moving mirror can vibrate and rotate simultaneously. The addition of the qubit affects the output probe field properties, and the study explores the impact of various parameters on transparency windows. The article reports a new discovery of triple-transparency windows in a single-cavity system. The study also investigates the slow and fast light propagation in the output probe field and discusses the Stokes and anti-Stokes powers in the proposed cavity system. The findings have implications for the development of future optical devices and quantum communication systems.

Acoustic scattering in lined panel cavities with membrane interfaces.

Noise control strategies are extremely important in industry. Acoustic liners and elastic membranes, which absorb or attenuate sound waves, are key components in ducting systems for active and passive noise reduction. In this article, we design and examine a reactive liner panel cavity with flexible interfaces. The lined panel cavity system is comprised of elastic membranes at the interfaces. The aim is to couple the incoming duct modes with the flexible components and then with the localized modes in the lined region. The governing equations for the lined panel cavity system are solved using a mode-matching technique that assures continuity of the normal velocities at the interfaces and can handle a range of strong coupling and higher-order edge conditions in contrast to the coupled mode theory. The aim is to investigate the effects of reactive liners and elastic membrane interfaces on wave scattering through the proposed acoustic enclosure design. The scattering performance of the proposed lined panel cavity is evaluated in terms of the reflected and transmitted energy flux as well as transmission loss. Analysis shows that the resonances at the membrane interfaces coupled to the linear cavities have a direct impact on power variations and the maximum transmission loss.

Pressure loss control in a rotor-stator cavity with inward throughflow

The back cavity of a centrifugal impeller is a typical rotor-stator cavity system with centripetal inflow in small or medium-sized aeroengines. In this paper, the effectiveness of using the “vortex control hole” structure to control the pressure loss in such a cavity is studied with experiment and numerical simulation. Vortex control hole refers to the passage connecting the internal and external air flow of the cavity. It distributes on the stationary casing circumferentially with a well-designed angle to produce an opposite tangential velocity to the main flow, thus reducing the tangential velocity of the main flow in the cavity. By controlling the swirl ratio, the pressure loss at cavity outlet could be decreased. The rotating Reynolds number Re φ = 6 × 105∼2.4 × 106, and turbulence parameter λt = 0.21∼0.55. Since the mainstream velocity has no tangential component at the inlet, it is considered that the inlet swirl ratio β0 is 0. The numerical simulation results were compared with the experimental results. The flow structure, the distribution of the swirl ratio, and the static pressure loss at the outlet of the cavity under different secondary air stream rates will be given. The coupling mechanism between the secondary airflow and the main flow in the cavity and the mechanism of the secondary air stream reducing the pressure loss in the disc cavity will be analyzed.

Topological magnon-photon interaction for cavity magnonics

The study of cavity magnonics and topological insulators has made significant advances over the past decade, however the possibility of combining the two fields is still unexplored. Here, we explore such connection by investigating hybrid cavity systems that incorporate both a ferromagnet and a topological insulator. We find that electrons in the topological surface state efficiently mediate the effective electric dipole coupling between the spin of the ferromagnet and the electric field of the cavity, in contrast with the conventional cavity magnonics theory based on magnetic dipole coupling. We refer to this coupling as topological magnon-photon interaction, estimating it one order of magnitude stronger than the conventional magnon-photon coupling, and showing that its sign can be manipulated. We discuss the potential of our proposed device to allow for scaling down and controlling the cavity system using electronics. Our results provide solid ground for exploring the functionalities enabled by merging cavity magnonics with topological insulators.

Controlling the electro-optic response of a semiconducting perovskite coupled to a phonon-resonant cavity

Optical cavities, resonant with vibrational or electronic transitions of material within the cavity, enable control of light-matter interaction. Previous studies have reported cavity-induced modifications of chemical reactivity, fluorescence, phase behavior, and charge transport. Here, we explore the effect of resonant cavity-phonon coupling on the transient photoconductivity in a hybrid organic-inorganic perovskite. To this end, we measure the ultrafast photoconductivity response of perovskite in a tunable Fabry–Pérot terahertz cavity, designed to be transparent for optical excitation. The terahertz-cavity field-phonon interaction causes apparent Rabi splitting between the perovskite phonon mode and the cavity mode. We explore whether the cavity-phonon interaction affects the material’s electron-phonon interaction by determining the charge-carrier mobility through photoconductivity. Despite the apparent hybridization of cavity and phonon modes, we show that the perovskite properties in both ground (phonon response) and excited (photoconductive response) states remain unaffected by the tunable light-matter interaction. Yet the response of the integral perovskite-terahertz optical cavity system depends critically on the interaction strength of the cavity with the phonon: the transient terahertz response to optical excitation can be increased up to threefold by tuning the cavity-perovskite interaction strength. These results enable tunable switches and frequency-controlled induced transparency devices.

On-chip topological THz biosensors

On-chip terahertz (THz) biosensors have enormous potential in advancing the development of integrable devices for real-time, label-free, and noninvasive detection of proteins, DNA, and cancerous tissue. However, high absorption of THz waves by water necessitates evanescent field-based biosensing. The conventional on-chip THz biosensors with small mode confinement volumes and scaling sensitivity to defects severely limit the interaction of analyte with the electromagnetic field. Here, we reveal a topological waveguide cavity system with topologically protected propagating interfacial modes, exhibiting evanescent waves with an out-of-plane field extent of 0.3λ0, where λ0 is the wavelength corresponding to the cavity resonance frequency. Our experiments involving biomolecule detection and leaf-hydration monitoring show that the near-field of high-Q topological cavity resonances accurately detects minute frequency shifts over extended periods, facilitating real-time sensing and monitoring of biological matter. Implementation of topologically protected evanescent fields in waveguide-cavity systems will enhance on-chip THz biosensing.

Characteristic test of dual shattered pellet injection systems of KSTAR

Dual shattered pellet injection (SPI) systems are installed in KSTAR (Korea Superconducting Tokamak Advanced Research) to study disruption mitigation in support of the ITER DMS (Disruption Mitigation System) design activities. KSTAR has two identical pellet injectors that can shoot pellets simultaneously from opposite toroidal locations. Each injector can shoot up to of three different diameter pellets. The pellet integrity and velocity after formation have been measured using microwave cavity (MWC) systems since 2019. However, this diagnostic provides only limited information on the pellet integrity, especially for partially broken pellets. Therefore, an optical pellet diagnostic (OPD) system monitoring the pellet has been installed in the first stage viewport of the differential pumping system and is operational since 2021. The KSTAR SPI systems offer a wide parameter range that must be characterized before the experimental campaign. To satisfy the experimental requirements, a proper procedure for pellet formation and acceleration must be commissioned. We carry out the commissioning by varying pellet parameters such as formation duration, temperature, heating, propellant gas pressure, and pulse length. The resulting pellet velocity, integrity, and tilt can be measured with the OPD system. These tests can be performed without plasma operation because no additional information is needed from the plasma response to the injection. This paper describes the results of the characteristic tests of single and multiple injections of dual SPI.

Parametric Study of Cavity IEMP Responses in a Cylinder by Coupling Monte Carlo Method and 3-D Electromagnetic Particle-in-Cell Method

Internal electromagnetic pulse generated inside a cavity, known as Cavity IEMP, would disturb or damage sensitive electronic systems inside a spacecraft when illuminated by transient X-rays. To ensure their normal operations, accurate prediction and analysis of Cavity IEMP responses are required. In this article, the physical phenomena involved in three-dimensional (3-D) Cavity IEMP problems are numerically studied, including the interaction process between X-rays and the cavity wall material and the self-consistent process involving the motion of electrons and the evolution of electromagnetic fields. The interaction process is simulated with the Monte Carlo method to obtain the actual emission characteristics of forward electrons emitted into a cavity, including their yields, energy, and angular spectra, while the self-consistent process is simulated with a proposed 3-D electromagnetic particle-in-cell method to solve electromagnetic fields generated inside a cavity, whose driving forces are forward electrons with the calculated emission characteristics. This method fully considers electrons with different energies and directions and their impacts on the generated electromagnetic fields. With such method, the electromagnetic field distribution inside a cylinder exposed to transient X-rays is discovered based on the actual emission characteristics of X-ray-induced forward electrons. Furthermore, as forward electron emission characteristics are determined by properties of X-rays and cavities, the impacts of the blackbody temperature in X-ray energy spectrum, the cylinder wall thickness, and the cylinder wall material on the intensity of generated electric fields are fully explored. Based on the results, several suggestions are given to protect electronic systems in cavities against the electromagnetic coupling from Cavity IEMP. The study would guide radiation hardening design of electronic systems in spacecraft.

A Quad-Band Near-Field Antenna Array for a Multistatic Microwave Imaging Chamber

A new quad-band tapered patch transmit-receive antenna array designed for a multistatic microwave imaging cavity system is presented. The reverberating cube-shaped chamber is filled with a matching fluid emulsion and encompasses 64 antenna elements mounted on its sidewalls (16 per panel). Four resonant frequencies that lie in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$0.5 - 3$</tex-math></inline-formula> GHz are achieved. The design procedure is provided based on system constraints and performance requirements that need to be taken into account: (1) the near-field nature of the electromagnetic wave in the presence of a shielded chamber and (2) the propagation of waves into the immersion fluid within the imaging domain. The antenna array design was numerically verified, and its prototype was fabricated. Results show good agreement between measurements and simulations, achieving antenna system performance requirements.

Detection of Porosity in Impregnated Die-Cast Aluminum Alloy Piece by Metallography and Computer Tomography

The porosity of die-cast aluminum alloys is a determining factor for the quality of the product. In this paper, we studied the porosity of a selected part of a die-cast AlSi9Cu3(Fe) compressor part by computer tomography and metallography. In the case of this part, the achievable resolution by CT, a non-destructive testing method, was 30 μm—this method could not detect smaller cavities. Based on metallographic analysis, the percentage of defects larger than 30 μm ranges from 10 to 30% of the total number of defects, which represents 75–95% of the defective area (area ratio). Impregnation with methacrylate resin (used to seal cavities to prevent leakage) can be detected with UV-illuminated optical microscopic examination on metallographically prepared specimens. As confirmed by scanning electron microscopy, partial filling and partial impregnation can occur in a system of shrinkage cavities.

Intralobar pulmonary sequestration with a rare source of arterial supply

BACKGROUND: Pulmonary sequestration is one of the most common malformations of the lungs in clinical practice. However, difficulties are possible in the interpretation of the radiological data, which leads to a violation of the examination technique in such patients and, accordingly, to the lack of success of the therapy and proper routing.&#x0D; AIM: To demonstrate the clinical case of a patient with intralobar pulmonary sequestration, describing the characteristic radiographic picture, and suggesting research methodology for the identified features of the aberrant vessel.&#x0D; METHODS: Clinical and radiological data of a 27-year-old patient with acute respiratory symptoms and suspected abscessed pneumonia based on X-ray and computed tomography (CT) findings were presented. Due to the absence of clinical and radiological dynamics, atypical CT semiotics of abscesses, CT angiography of the thoracic aorta was performed after intravenous contrast enhancement with 80 ml of iodine-containing preparation (350 mg/mL).&#x0D; RESULTS: A pulmonary tissue thickening was revealed in the lower left lobe with lumpy clear contours, which consisted of a system of cystic cavities with contents, particularly well differentiated after contrast enhancement. On the native study, an additional vascular structure following from the subdiaphragmatic space was traced paravertebrally, which was the reason for extending the CT angiography scanning area to the epigastric region of the abdomen. A large-caliber arterial vessel was detected, which departed as a branch from the celiac trunk and passed to the above-described thickening of the pulmonary tissue. The combination of these signs is typical for intrapulmonary sequestration.&#x0D; CONCLUSIONS: The correct interpretation of the identified changes allowed the patient to be routed to a hospital with a thoracic surgery department, since the sequestration must be removed in the vast majority of cases to prevent recurrent inflammatory episodes. Extension of the scanning area below the diaphragm may be useful, since part of the sequesters is supplied with blood from the abdominal aorta and its visceral branches. This will prevent the need for repeat CT angiography, and information about the source of the blood supply is extremely important for surgeons.

THE IMPACT OF FIXED DENTURES ON THE TISSUES OF THE ORAL CAVITY AND THE COURSE OF GASTROINTESTINAL DISEASES

The article presents the results of scientific research on the negative impact of fixed denture structures on the tissues of the oral cavity and gastrointestinal tract in patients with chronic gastritis.&#x0D; The relevance of the work lies in the fact that orthopedic treatment not only eliminates aesthetic defects, restores the impaired function of the dentoalveolar system, but also has a significant preventive value for the prevention of gastrointestinal diseases.&#x0D; The aim of our research was to study the effect of fixed dentures made of different structural materials on the tissues of the oral cavity and gastrointestinal tract in chronic gastritis.&#x0D; Objects and methods of the study. We examined patients of the gastroenterological department who were inpatients with chronic gastritis and used fixed dentures.&#x0D; The examination took into account complaints of burning sensation, itching, redness of the gingival mucosa, gingival swelling, increased salivation or dryness in the oral cavity, heightened perception of acidity and the presence of microcurrents in the oral cavity; type of denture and visually determined the material from which it is made; compliance of the denture with clinical and technological requirements, the period of its use, diagnosis of the underlying disease for which the patient is undergoing inpatient treatment.&#x0D; Study results and conclusions. According to the results of the study, it was found that out of 86 patients examined, 44 patients (51.16%) of both groups used soldered bridges, 42 (48.84%) full-cast bridges. Pathological manifestations of the negative effects of soldered dentures in the oral cavity and gastrointestinal tract were detected in 41 of 44 patients, which is 47.7% of the total number of patients examined. Out of 42 patients (48.84%) in both groups, 11 (12.8%) had full-cast bridges.&#x0D; Soldered bridges cause 35% more complications in the oral cavity and digestive system than full-cast dentures. Negative manifestations and exacerbation of somatic pathology when using fixed dentures are observed 3 times more often in patients with hyperacid gastritis.

Tunable optical response properties in a Laguerre-Gaussian rovibrational cavity system with a mechanical pump

Tunable optical response properties in a Laguerre-Gaussian rovibrational cavity system with a mechanical pump

Design and implementation of a remote monitoring system of mold cavity using eject pin in high-pressure die casting

ABSTRACT This research presents a design process for mould cavity monitoring with a temperature and force-generated pressure measurement system in high-pressure Die casting (HPDC). K-type thermocouple sensor was selected to measure the harsh environment of the Mould Cavity. An eject pin was processed and used for the installation of the sensor in the measurement system, and data was collected from the sensor and displayed as a real-time graph. The rationality of the obtained data was verified with comparative analysis with finite element analysis simulation (FEM) result as a reverse engineering approach. The proposed system is successfully measuring and monitoring the temperature and pressure inside the mould, allowing for the safe monitoring of Die casting. Through monitoring, abnormal conditions in the process can be detected. It is expected that this will reduce the defect rate and improve the quality of manufactured products.

Numerical investigation on the effects of HC geometry on the flow and heat transfer in the disk cavity system at the turbine vane root

In this study, we numerically investigate the flow and heat transfer in the sealing system at the vane root of a heavy-duty turbine with the aim of determining the optimal geometry of honeycomb cells within a certain parameter range. First, we analyze the impact of honeycomb cell geometry on flow in the sealing gaps, including flow rotation, energy dissipation in the teeth chamber and honeycomb cell, and frictional losses. Next, we examine the heat transfer capacity between the leakage flow and the surfaces of the rotor or stator, and establish the relationship between the stream function and the average heat transfer coefficient. Third, we compare the predicted core swirl ratio, the most important aerodynamic parameter in disk cavities, with those from equations in the literature. The decrease in core swirl ratio in the upstream disk cavity indicates that the use of different honeycomb cell geometries may lead to excessive axial thrust. Finally, we study the local and average heat transfer capacities on the turbine disk and introduce a correction factor (0.12–0.21) into the correlation to make it applicable to analogous turbine disks or rotor–stator cavities in other turbo machines with low radii honeycomb labyrinth seals. Based on our findings, we provide recommendations for the optimal honeycomb cell geometries for the two sealings for different targets. These results serve as a reference for designers of honeycomb labyrinth seals for gas turbines and other turbo machines.

Hyaluronic acid-based nanoparticles to deliver drugs to the ocular posterior segment

Ocular posterior segment diseases such as uveitis, X-linked juvenile retinoschisis, or age-related macular degeneration usually result in progressive and irreversible vision loss. Although intravitreal injection is the main way to deliver drugs to the posterior eye, it still has shortcomings as an invasive operation. Nanocontrolled drug delivery technology is a promising option to avoid frequent injections. Due to the particularity of the human intraocular structure, drugs have unique pharmacokinetic characteristics in the eye. Various nanoparticles have been successfully investigated in experimental studies for vitreous injection, with advantages and drawbacks. Here, we introduce an ideal nanopolymer modifier to build nanodelivery systems in vitreous cavities. Hyaluronic acid (HA) is a natural polysaccharide with a broad molecular weight range, negatively charged surface, ligand–receptor binding capabilities, and hyaluronidase breakdown capability. Advances in CD44 receptor targeting for HA-based nanoparticles can improve mobility and penetration in the vitreous and retina, stabilize the nanoparticles, and regulate drug release. This review summarizes the intravitreal administration of nanoplatforms based on HA and the benefits of HA in drug delivery systems.

Multimode hybridizations in surface plasmon resonances excited in terahertz dipole cavities

Inventive design variations in subwavelength plasmonic structures can excite unconventional surface plasmon resonances (SPRs) that can enormously contribute to developing futuristic terahertz (THz) devices and components. Therefore, in this work, we demonstrate multimode resonance features in SPR characteristics through the introduction of split-ring resonators (SRRs) in plasmonic dipole cavities operating in the THz domain. Here, we propose a hybrid plasmonic system, where a single SRR is placed in the middle of a dipole cavity sustaining SPRs in the THz domain. Further, the SRR is displaced in orthogonal directions (horizontally as well as vertically) from the center of the cavity introducing asymmetry in the hybrid SRR–dipole cavity system. In such a way, introduced asymmetry resulted in diverse transmission responses with the realization of multiple SPR peaks. Such multi-SPR features are explicated using two-state and three-state mode hybridization schemes, which arise due to the near-field electric coupling between the SRR and the dipole cavity. Our findings based on multimode SPR characteristics excited in planar dipole cavities can contribute to realizing compact biosensor, absorber, and nonlinear THz devices operating simultaneously in multiple frequency bands.

Collapse-revival and stability of magnon-superconducting qubit entanglement in a tripartite hybrid cavity system

In this paper we pay our attention to the generation and manipulation of bipartite entanglement in a hybrid cavity system which is comprised of cavity microwave photons, a magnon and a superconducting qubit. To achieve the purpose of paper, at first, the time-independent effective Hamiltonian of the system is derived with considering some assumptions, and then the system solution is obtained via solving the Lindblad master equation. At last, the bipartite magnon-superconducting qubit entanglement is quantitatively analyzed using negativity, as a suitable measure of bipartite entanglement. The numerical simulations obviously show that, by adjusting system parameters, collapse-revival behavior of the entanglement can be apparently observed, and by appropriate choice of thermal occupation photon number and cavity decay rate, quasi-stable, even stable with significant degrees of entanglement are accessible. Our results indicate that, such a hybrid cavity system considered here can be used for studying large-scale quantum phenomena which has a crucial role in quantum information science and technologies.