Search

This study is started from a photon-magnon model with a competition effect of the level attraction and repulsion, its Hermiticity is mainly decided by a phase-dependent and asymmetric coupling factor, namely φ = 0 for Hermitian and ϕ = π for non-Hermitian. Then an extensional study predicts the quantum critical behaviors using an Hermitian and even no-Hermitian photon-spins model with an additional second-order drive. The numerical results firstly indicate that this coupling phase φ can function the protective effect on quantum phase transitions (QPTs), and the new tricritical points can not only be modulated by this nonlinear drive, but also be influenced by the dissipation and the collective decoherence. Secondly, this competition effect can also induce a reversal of the value of order parameters between the positive and negative. This study can also bring more important results of QPTs toward the issue of symmetry breaking and non-Hermiticity.

With the explosive growth of ocean data, ocean big data has received more and more attention. It mainly analyzes and summarizes the current research status and key technologies of ocean big data, and focuses on the examples of machine learning model prediction research in ocean big data. With the advancement of 3S technology, China’s marine monitoring network has achieved all-round development, including air, ground, and sea monitoring platforms, which has promoted the rapid growth of marine big data from the original GB and TB levels to PB levels. Taking the typhoon disaster search and situation display implementation as an example, the thesis has preliminarily completed the realization and application of the intelligent ocean search engine. Combined with the design of typhoon disaster search and the overall structure and function design of the situation display, module development was carried out, and the development was initially completed to realize the business data management of marine typhoon disaster mitigation based on big data.

A multifunctional surface plasmon polariton disk device coupled by two metal?insulator?metal (MIM) waveguides is proposed and investigated numerically with finite-difference time-domain simulation. It can be used as optical switch and temperature sensor by filling disk with liquid crystal and ethanol, respectively. The simulation results demonstrate that the transmission characteristics of an optical switch can be manipulated by adjusting the radius of disk and the slit width between disk and MIM waveguides. The transmittance and modulation depth of optical switch at 1550?nm are up to 64.82% and 17.70?dB, respectively. As a temperature sensor, its figure of merit can reach 30.46. In this paper, an optical switch with better efficiency and a temperature sensor with better sensitivity can be achieved.

Schemes for two-qubit and three-qubit controlled gates based on cross-Kerr nonlinearity are proposed in this paper. The probability of the success of these gates can be increased by quantum nondemolition detectors, which are used to judge which paths the signal photons pass through. These schemes are almost deterministic and require no ancilla photon. The advantages of these gates over the existing ones include less resource consumption and a higher probability of success, which make our schemes more feasible with current technology.

We present a scheme for quantum superdense coding with hyperentanglement, in which the sender can transfer four bits of classical information by sending only one photon. The important device in the scheme is the hyperentangled Bell-state analyzer in both polarization and frequency degrees of freedom, which is also constructed in the paper by using a quantum nondemolition detector assisted by cross-Kerr nonlinearity. Our scheme can transfer more information with less resources than the existing schemes and is nearly deterministic and nondestructive.