Time Symmetry Analysis of Nonlinear Parity Based on S-P Compensation Network Structure

The wireless power transmission system based on nonlinear parity time symmetry is a robust sys-tem that can maintain high-efficiency transmission at a certain distance.Parity-Time Symmetry(PT symmetry)wireless power transfer system,due to its insensitivity to the position of the coupled resonant coil over a large range,can carry out constant power transfer to the load,and through coupled mode theory The PT symmetrical wireless power transmission circuit with S-P structure is analyzed,and the system has different transmission efficiencies in different coupling intervals,and the transmission effect of the structure at different distances is studied with the change of coupling coefficient.Then,the simulation is carried out by MATLAB and origin software.The final results show that the transmission efficiency does not change with the coupling coefficient in the strong coupling region and can maintain high-efficiency transmission.In the weak coupling region,the coupling coefficient has a great influence on the transmission efficiency of the system.

Majorana tunneling in a one-dimensional wire with non-Hermitian double quantum dots

The combination of non-Hermitian physics and Majorana fermions can give rise to new effects in quantum transport systems. In this work, we investigate the interplay of PT-symmetric complex potentials, Majorana tunneling and interdot tunneling in a non-Hermitian double quantum dots system. It is found that in the weak-coupling regime the Majorana tunneling has pronounced effects on the transport properties of such a system, manifested as splitting of the single peak into three and a reduced 1/4 peak in the transmission function. In the presence of the PT-symmetric complex potentials and interdot tunneling, the 1/4 central peak is robust against them, while the two side peaks are tuned by them. The interdot tunneling only induces asymmetry, instead of moving the conductance peak, due to the robustness of the Majorana modes. There is an exceptional point induced by the union of Majorana tunneling and interdot tunneling. With increased PT-symmetric complex potentials, the two side peaks will move towards each other. When the exceptional point is passed through, these two side peaks will disappear. In the strong-coupling regime, the Majorana fermion induces a 1/4 conductance dip instead of the three-peak structure. PT-symmetric complex potentials induce two conductance dips pinned at the exceptional point. These effects should be accessible in experiments.

The contrast between defect solitons in parity-time symmetric superlattice and simple-lattice complex potentials

The existence and stability of defect superlattice solitons in parity-time （PT） symmetric superlattice and simplelattice complex potentials are reported. Compared with defect simple-lattice solitons in similar potentials, the defect soliton in superlattice has a wider stable range than that in simple-lattice. The solitons＇ power increases with increasing propagation constant. For the positive defect, the solitons are stable in the whole region where solitons exist in the semi-infinite gap. For the zero defect, the solitons are unstable at the edge of the band. For the negative defect, the solitons propagate with the shape of Y at low propagation constant and propagate stably at the large one.

Lie Symmetries,Conservation Laws and Explicit Solutions for Time Fractional Rosenau–Haynam Equation

Under investigation in this paper is the invariance properties of the time fractional Rosenau-Haynam equation, which can be used to describe the formation of patterns in liquid drops. By using the Lie group analysis method, the vector fields and symmetry reductions of the equation are derived, respectively. Moreover, based on the power series theory, a kind of explicit power series solutions for the equation are well constructed with a detailed derivation. Finally, by using the new conservation theorem, two kinds of conservation laws of the equation are well constructed with a detailed derivation.

A high SFDR 6-bit 20-MS/s SAR ADC based on time-domain comparator

This paper presents a 6-bit 20-MS/s high spurious-free dynamic range（SFDR） and low power successive approximation register analog to digital converter（SAR ADC） for the radio-frequency（RF） transceiver frontend, especially for wireless sensor network（WSN） applications.This ADC adopts the modified common-centroid symmetry layout and the successive approximation register reset circuit to improve the linearity and dynamic range. Prototyped in a 0.18-μm 1P6M CMOS technology,the ADC performs a peak SFDR of 55.32 dB and effective number of bits（ENOB） of 5.1 bit for 10 MS/s.At the sample rate of 20 MS/s and the Nyquist input frequency,the 47.39-dB SFDR and 4.6-ENOB are achieved.The differential nonlinearity（DNL） is less than 0.83 LSB and the integral nonlinearity（INL） is less than 0.82 LSB.The experimental results indicate that this SAR ADC consumes a total of 522μW power and occupies 0.98 mm^2.

Interplay of nonreciprocity and nonlinearity on mean-field energy and dynamics of a Bose–Einstein condensate in a double-well potential

We investigate the mean-field energy spectrum and dynamics in a Bose–Einstein condensate in a double-well potential with non-Hermiticity from the nonreciprocal hopping,and show that the interplay of nonreciprocity and nonlinearity leads to exotic properties.Under the two-mode and mean-field approximations,the nonreciprocal generalization of the nonlinear Schrödinger equation and Bloch equations of motion for this system are obtained.We analyze the PT phase diagram and the dynamical stability of fixed points.The reentrance of PT-symmetric phase and the reformation of stable fixed points with increasing the nonreciprocity parameter are found.Besides,we uncover a linear selftrapping effect induced by the nonreciprocity.In the nonlinear case,the self-trapping oscillation is enhanced by the nonreciprocity and then collapses in the PT-broken phase,and can finally be recovered in the reentrant PT-symmetric phase.

Nonreciprocal transition between two indirectly coupled energy levels

We propose a theoretical scheme to realize nonreciprocal transition between two energy levels that can not coupled directly.Suppose they are coupled indirectly by two auxiliary levels with a cyclic four-level configuration,and the four transitions in the cyclic configuration are controlled by external fields.The indirectly transition become nonreciprocal when the time reversal symmetry of the system is broken by the synthetic magnetic flux,i.e.,the total phase of the external driving fields through the cyclic four-level configuration.The nonreciprocal transition can be identified by the elimination of a spectral line in the spontaneous emission spectrum.Our work introduces a feasible way to observe nonreciprocal transition in a wide range of multi-level systems,including natural atoms or ions with parity symmetry.

A novel timing synchronization for CO-OFDM systems using CAZAC sequences

A novel symbol timing synchronization algorithm based on constant amplitude zero auto correlation(CAZAC) sequences is proposed for coherent optical orthogonal frequency division multiplexing(CO-OFDM) systems. The training symbol of the proposed algorithm is comprised of four different parts, utilizing even symmetry property of each part to accomplish timing synchronization. The performance of the proposed algorithm is demonstrated by means of simulations in OFDM and CO-OFDM systems. The proposed algorithm is shown to eliminate the timing sidelobes of Park's algorithm and has a more accurate timing estimation. In the condition of chromatic dispersion(CD), the timing metric of the proposed method still maintains its peak value at the correct timing point, while the values are almost 0 at all the other positions. Meanwhile, the timing mean square error(MSE) of the proposed algorithm remains around 10^(-6).