AAPPS Bulletin最新文献

We present a microscopic many-body calculation of the nonlinear two-dimensional coherent spectroscopy (2DCS) of trion-polaritons and exciton-polaritons in charge-tunable transition-metal-dichalcogenides monolayers placed in an optical microcavity. The charge tunability leads to an electron gas with nonzero density that brings brightness to the trion — a polaron quasiparticle formed by an exciton with a nonzero residue bounded to the electron gas. As a result, a trion-polariton is created under strong light-matter coupling, as observed in the recent experiment by Sidler et al. [Nat. Phys. 13, 255 (2017)]. We analyze in detail the structure of trion-polaritons, by solving an extended Chevy ansatz for the trion quasiparticle wave-function. We confirm that the effective light-matter coupling for trion-polaritons is determined by the residue of the trion quasiparticle. The solution of the full many-body polaron states within Chevy ansatz enables us to microscopically calculate the nonlinear 2DCS spectrum of both trion-polaritons and exciton-polaritons. We predict the existence of three kinds of off-diagonal cross-peaks in the 2DCS spectrum, as an indication of the coherence among the different branches of trion-polaritons and exciton-polaritons. Due to the sensitivity of 2DCS spectrum to quasiparticle interactions, our work provides a good starting point to explore the strong nonlinearity exhibited by trion-polaritons in some recent exciton-polariton experiments.

The atomic clocks, whether operating at optical or microwave region, can be divided into two categories according to their working mode, namely the passive clocks and active clocks. The passive clocks, whose standard frequency is locked to an ultra-narrow atomic spectral line, such as laser cooled Cs beam or lattice trapped Sr atoms, depend on the spontaneous emission line. On the contrary, the active clocks, in which the atoms are used as the gain medium, are based on the stimulated emission radiation, their spectrum can be directly used as the frequency standard. Up to now, the active hydrogen maser has been the most stable microwave atomic clocks. Also, the Sr superradiant active atomic clock is prospects for a millihertz-linewidth laser. Moreover, the optical clocks are expected to surpass the performance of microwave clocks both in stability and uncertainty, since their higher working frequency. The active optical clock has the potential to improve the stability of the best clocks by 2 orders of magnitude. In this work, we introduce the development of active optical clocks, and their types is classified according to the energy-level structure of atoms for stimulated radiation.

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.