AAPPS Bulletin最新文献

Experimental Advanced Superconducting Tokamak (EAST) was built to demonstrate high-power, long-pulse operations under fusion-relevant conditions, with major radius R = 1.9 m, minor radius a = 0.5 m, and design pulse length up to 1000s. It has an ITER-like D-shaped cross-section with two symmetric divertors at the top and bottom, accommodating both single null and double null divertor configurations. EAST construction was started in 2000, and its first plasma was successfully obtained in 2006. In the past 15 years, plasma-facing components, plasma heating, diagnostics, and other systems have been upgraded step by step to meet its mission on exploring of the scientific and technological bases for fusion reactors and studying the physics and engineering technology issues with long pulse steady-state operation. An advanced steady-state plasma operation scenario has been developed, and plasma parameters were greatly improved. Meanwhile, front physics on the magnetic confinement plasmas have been systemically investigated and lots of fruitful results were realized, covering transport and confinement, MHD stabilities, pedestal physics, divertor and scrap-off layer (SOL) physics, and energetic particle physics. This brief review of EAST on engineering upgrading, stand-steady operation scenario development, and plasma physics investigation would be useful for the reference on construction and operation of a superconducting tokamak, such as ITER and future fusion reactor.

Squeezed vacuum state of light is an important concept of quantum optics which has an uncertainty reduction in a specific quadrature compared to the coherent vacuum state. The coherent Ising machines (CIMs) based on the squeezed state are capable of searching the ground state of the Ising model, which can be used to solve combinatorial optimization problems and have been experimentally demonstrated to have excellent computational performance. This review introduces the recent progress of a CIM hardware solver based on optical parametric oscillators, including the delayed optical path scheme and a measurement feedback scheme. Also, the basic principles, unique advantages, and potential challenges are described. We expect that the applications of large-scale CIM hardware solvers will have a huge impact on the acceleration of the computation power.

We briefly review the status of applying quantum squeezing to aid the search for gravitational waves with km-scale laser interferometers operating in the audio frequency band. The target audience is quantum optics professionals who are interested in an easily accessible introduction to the gravitational wave detector, both as an application of squeezing and as a platform for developing other quantum techniques.

Carbon-based materials (CM) growth techniques include common growth factors for meta-photonics-heterostructure, holographic displays, and lasers. In this article, a review of basic growth using several sources is presented. The solid and gas sources of CVD and PLD techniques are discussed. Additionally, doping types and the fabrication of the CM devices are covered to satisfy the requirements of the light emitters’ functionality in the physics of materials as follows: (a) direct bandgap, (b) UV range of 0.1 μm < λ_G < 0.4 μm, 12.40 eV < E_G > 3.10 eV, and (c) p-n junction formation. Additionally, conversion of injected electrical current into light in the semiconductor materials using the anti-electrons process for creating light emitters is proposed. Therefore, this review study explores the potential of the selected CM sources as an inexpensive and abundantly available renewable natural source for highly crystalline nanolayers. The CM status of epitaxial thin-film growth is introduced as well as device-processing technologies for prediction. Finally, the positron process in direct light conversion is discussed.

Quantum systems are under various unwanted interactions due to their coupling with the environment. Efficient control of quantum system is essential for quantum information processing. Weak-coupling interactions are ubiquitous, and it is very difficult to suppress them using optimal control method, because the control operation is at a time scale of the coherent life time of the system. Nitrogen-vacancy (NV) center of diamond is a promising platform for quantum information processing. The (^{13})C nuclear spins in the bath are weakly coupled to the NV, rendering the manipulation extremely difficulty. Here, we report a coupling selective optimal control method that selectively suppresses unwanted weak coupling interactions and at the same time greatly prolongs the life time of the wanted quantum system. We applied our theory to a 3 qubit system consisting of one NV electron spin and two (^{13})C nuclear spins through weak-coupling with the NV center. In the experiments, the iSWAP(^{dagger }) gate with selective optimal quantum control is implemented in a time-span of (T_{ctrl})= 170.25 (mu)s, which is comparable to the phase decoherence time (T_2)= 203 (mu s). The two-qubit controlled rotation gate is also completed in a strikingly 1020(80) (mu)s, which is five times of the phase decoherence time. These results could find important applications in the NISQ era.

A new rare-isotope beam (RIB) accelerator complex, RAON, is under construction in South Korea. RAON employs two RIB production methods, namely, isotope separation online (ISOL) and in-flight fragmentation (IF). According to the original design, ISOL and IF can run independently, and RAON ultimately combines them to provide more neutron-rich ion beams for the experiments. In 2021, due to the delay in developing high-energy superconducting cavities and modules, it was decided to proceed with the RAON construction project in two steps. In the first phase, the injector system, the low-energy accelerator system, ISOL, the IF separator, and all experimental devices will be completed by the end of 2022. The high-energy accelerator system will be developed, manufactured, installed, and commissioned in the second phase. In this article, the status of the superconducting accelerators, RIB production systems, and experimental equipment for RAON is reviewed.

Classical magnetic fields might change the properties of topological insulators such as the time reversal symmetry protected topological edge states. This poses a question that whether quantized fields would change differently the feature of topological materials with respect to the classical one. In this paper, we propose a model to describe topological insulators (ultracold atoms in square optical lattices with magnetic field) coupled to a tunable single-mode quantized field, and discuss the topological features of the system. We find that the quantized field can induce topological quantum phase transitions in a different way. To be specific, for fixed gauge magnetic flux ratio, we calculate the energy bands for different coupling constants between the systems and the fields in both open and periodic boundary conditions. We find that the Hofstadter butterfly graph is divided into a pair for continuous gauge magnetic flux ratio, which is different from the one without single-mode quantized field. In addition, we plot topological phase diagrams characterized by Chern number as a function of the momentum of the single-mode quantized field and obtain a quantized structure with non-zero filling factor.