New approach for analysing master equations of generalized phase diffusion models in the entangled state representation

By virtue of the well-behaved properties of the bipartite entangled states representation, this paper analyse and solves some master equations for generalized phase diffusion models, which seems concise and effective. This method can also be applied to solve other master equations.

Phase Properties of Two-Mode Squeezing-Rotating Entangled Representation

By virtue of the squeezing-rotating entangled representation, we mainly establish the new two-mode phase operator and phase angle operat, or, which is a general form including the foregoing formalist in two-mode Fock space. In addition, the corresponding phase distribution function is given in the entangled representation. In terms of this definition, we also analyze the phase behavior of some simple two-mode states such as squeezing-rotatlng coherent state, squeezing-rotating vacuum state, and so on. It is found that the results exactly agree with the foregoing phase theory.

New < q,n|| Representation for Studing Two-Mode Nonlinear Phase Operator

A new complete and orthonormal < q,n|| representation is constructed in which Hradil’s two-mode phase operator R exhibits its phase behavior manifestly and can be put into R = Σ^(∞)_(q=-∞)Σ^(∞)_(n=0) ||q-1,n> < q, n||, which resembles S-G phase operator (N + l)^(-1/2a) = Σ^(∞)_(n=1|n–l > < n|). The corresponding phase state is also obtained, which is quaJified to make up a phase representation.

Methods for Derivation of Density Matrix of Arbitrary Multi-Mode Gaussian States from Its Phase Space Representation

We present a method for derivation of the density matrix of an arbitrary multi-mode continuous variable Gaussian entangled state from its phase space representation.An explicit computer algorithm is given to reconstruct the density matrix from Gaussian covariance matrix and quadrature average values.As an example,we apply our method to the derivation of three-mode symmetric continuous variable entangled state.Our method can be used to analyze the entanglement and correlation in continuous variable quantum network with multi-mode quantum entanglement states.

Comparison between magnitude reconstruction and phase-sensitive mR imaging in the detection of myocardial infarction

Objective:To determine the deference between phase sensitive magnetic resonance(MR) imaging and magnitude reconstruction to detect infracted myocardium.Methods:Twenty patients(16 men;4 women;mean age,56 years),experienced Q-wave myocardial infarction 2 weeks earlier were examined with a 3.0-T MR system 10 minutes after administration of 0.1 mmol/kg body weight gadobenate dimeglumine.To determine the optimal TI,a TI scout sequence was used.A segmented 2D IR true fast imaging with steady-state precession(trueFISP) sequence that produces both phase-sensitive and magnitude-reconstructed images were used at TI values of 200-600 msec(TI values were varied in 100-msec steps) and at optimal TI(mean value,330 msec).Contrast- noise ratios(CNRs) of normal and infarcted myocardium and the area of infarcted myocardium were determined.Two-tailed unpaired sample Student t test was used to compare CNRs,and area of infarction.Results:MMean CNR phase-sensitive and magnitude-reconstructed images at optimal TI(mean value,330 msec) were 6.2,and 6.1,respectively.For a TI of 200 msec,CNR values were 5.5,and 4.2,respectively;for TI of 600 msec,CNR values were 5.8 and 4.3,respectively.Area of infarcted myocardium was underestimated on magnitude-reconstruction images(P = 0.002-0.03) for short TI values(ie.,200 msec) but not on phase sensitive reconstructed when compared with IR tureFISP images obtained at optimal TI.Conclusions: LPhase-sensitive image reconstruction results in reduced need for precise choice of TI and more consistent image quality.

New Approach for Solving Master Equations in Quantum Optics and Quantum Statistics by Virtue of Thermo-Entangled State Representation

By introducing a fictitious mode to be a counterpart mode of the system mode under review we introduce the entangled state representation （η｜, which can arrange master equations of density operators p（t） in quantum statistics as state-vector evolution equations due to the elegant properties of （η｜. In this way many master equations （respectively describing damping oscillator, laser, phase sensitive, and phase diffusion processes with different initial density operators） can be concisely solved. Specially, for a damping process characteristic of the decay constant k we find that the matrix element of p（t） at time t in 〈η｜ representation is proportional to that of the initial po in the decayed entangled state （ηe^-kt｜ representation, accompanying with a Gaussian damping factor. Thus we have a new insight about the nature of the dissipative process. We also set up the so-called thermo-entangled state representation of density operators, ρ = f（d^2η/π）（η｜ρ〉D（η）, which is different from all the previous known representations.

Hermitian Operators Conjugate to Two-Mode Number-Difference Operator Studied in Entangled State Representation

In similar to the derivation of phase angle operator conjugate to the number operator by Arroyo Carrasco-Moya Cessay we deduce the Hermitian phase operators that are conjugate to the two-mode number-difference operatorand the three-mode number combination operator.It is shown that these operators are on the same footing in theentangled state representation as the one of Turski in the coherent state representation.

Numerical Convergence of the Sinc Discrete Variable Representation for Solving Molecular Vibrational States with a Conical Intersection in Adiabatic Representation

Within the Born-Oppenheimer(BO)approximation,nuclear motions of a molecule are often envisioned to occur on an adiabatic potential energy surface(PES).However,this single PES picture should be reconsidered if a conical intersection(CI)is present,although the energy is well below the CI.The presence of the CI results in two additional terms in the nuclear Hamiltonian in the adiabatic presentation,i.e.,the diagonal BO correction(DBOC)and the geometric phase(GP),which are divergent at the CI.At the same time,there are cusps in the adiabatic PESs.Thus usually it is regarded that there is numerical difficulty in a quantum dynamics calculation for treating CI in the adiabatic representation.A popular numerical method in nuclear quantum dynamics calculations is the Sinc discrete variable representation(DVR)method.We examine the numerical accuracy of the Sinc DVR method for solving the Schrodinger equation of a two dimensional model of two electronic states with a CI in both the adiabatic and diabatic representation.The results suggest that the Sinc DVR method is capable of giving reliable results in the adiabatic representation with usual density of the grid points,without special treatment of the divergence of the DBOC and the GP.The numerical uncertainty is not worse than that after the introduction of an arbitrary vector potential for accounting the GP,whose accurate form usually is not easy to obtain.

Metrology of Optical Communication Systems Using Error Vector Magnitude

Error vector magnitude (EVM) as a performance metric for M-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presented. It is shown that the calibrated BER, which would otherwise be under-estimated without the correction factor, can reliably monitor the performance of optical coherent systems near the target BER of 10-3 for quadrature phase shift keying (QPSK), 16-QAM, and 64-QAM employing carrier phase recovery with differential decoding to compensate for laser phase noise. The impact on the number of symbols used to estimate the BER from EVM analysis is also presented and compared to the BER obtained by error counting.

NeuPh:scalable and generalizable neural phase retrieval with local conditional neural fields

Deep learning has transformed computational imaging,but traditional pixel-based representations limit their ability to capture continuous multiscale object features.Addressing this gap,we introduce a local conditional neural field(LCNF)framework,which leverages a continuous neural representation to provide flexible object representations.LCNF’s unique capabilities are demonstrated in solving the highly ill-posed phase retrieval problem of multiplexed Fourier ptychographic microscopy.Our network,termed neural phase retrieval(NeuPh),enables continuous-domain resolution-enhanced phase reconstruction,offering scalability,robustness,accuracy,and generalizability that outperform existing methods.NeuPh integrates a local conditional neural representation and a coordinate-based training strategy.We show that NeuPh can accurately reconstruct high-resolution phase images from low-resolution intensity measurements.Furthermore,NeuPh consistently applies continuous object priors and effectively eliminates various phase artifacts,demonstrating robustness even when trained on imperfect datasets.Moreover,NeuPh improves accuracy and generalization compared with existing deep learning models.We further investigate a hybrid training strategy combining both experimental and simulated datasets,elucidating the impact of domain shift between experiment and simulation.Our work underscores the potential of the LCNF framework in solving complex large-scale inverse problems,opening up new possibilities for deep-learning-based imaging techniques.

Continuous frequency and phase spectrograms: a study of their 2D and 3D capabilities and application to musical signal analysis

A new lighting and enlargement on phase spectrogram （PS） and frequency spectrogram （FS） is presented in this paper. These representations result from the coupling of power spectrogram and short time Fourier transform （STFT）. The main contribution is the construction of the 3D phase spectrogram （3DPS） and the 3D frequency spectrogram （3DFS）. These new tools allow such specific test signals as small slope linear chirp, phase jump case of musical signal analysis is reported. The main objective is to and small frequency jump to be analyzed. An application detect small frequency and phase variations in order to characterize each type of sound attack without losing the amplitude information given by power spectrogram

Cooper-pair number-phase quantization analysis in double-Josephson-junction mesoscopic circuit coupled by a capacitor

This paper examines the quantization of mesoscopic circuit including Josephson junctions. Following Feynman＇s assumption, via the Hamilton dynamic approach and by virtue of the entangled state representation, it constructs Hamiltonian operator for the double-Josephson-junction mesoscopic circuit coupled by a capacitor. Then it uses the Heisenberg equation of motion to derive the induction voltage across each Josephson junction. The result manifestly shows how the voltage is affected by the capacitance coupling.

Microwave Oscillator Phase Noise Requirement for TD-SCDMA Wireless Communication Systems

In time division synchronous code division multiple access （TD-SCDMA） wireless communication systems, QPSK or 8PSK has been employed to support high data rate services and high efficiency in available bandwidth. The performance of such systems is affected by the phase noise of the microwave local oscillator. The phase noise model of synthesizer and the RF transceiver model for the phase noise effect are proposed for applications of TD-SCDMA systems. The relationship between the power spectral density （PSD） and root mean square （RMS） phase error is given. Then, the error vector magnitude （EVM） performance is analytically evaluated by using the single side band （SSB） phase noise. Theoretical results show agreement with those obtained by measurement data and therefore can be used to derive the TD-SCDMA system performance.

On some problems of seismic crustal phase

In this paper, some practical problems in seismological observations are discussed on the identification of seismiccrustal phase, such as: “whether P (Pg) and S(Sg) are direct waves or not?”; “whether S(Sg) and Lg as well asng and P (Pg) are two kinds of waves or identical wave?”;“on seismoiogicai phases in regional travel-timetable”;“on the symbols and identifications of phases in seismological observation repors”;“on the relation between mLg and ML”, and so on. Some confused ideas on these problems are clarified.

An Alternative Three-phase Transmission Lines Model in Phase Domain

The objective of this paper is to show an alternative model of a non-transposed three-phase transmission line with a vertical symmetry plane in phase domain. Due the line physical characteristics, it can be represented by a system consisting of a single?phase and a two-phase line. In this system, the equations describing the behavior of the values in single-phase line terminals are known, while the equations for two-phase line to be obtained. Using a transformation matrix written explicitly according to three-phase line parameters, it is possible to obtain the currents and voltages in phase domain of two-phase line. Then, modal values of three-phase line are converted into phase domain and thus obtain the analytical model for this line. To verify the performance of this model, it was used to simulate the energization of a 440 kV three-phase line and the results were compared to results obtained using a classical model.

Phase State as a Limiting Case of SU(1,1) Coherent State

We show that the Susskind-Glogower phase state is a limiting case of a kind of SU（1,1） coherent states. By analogy, based on the bipartite entangled state representation （ESR） we demonstrate that an appropriate SU（1,1） coherent state composed of the two-mode unitary phase operator e^i also leads to a new phase state in two-mode Fock space, e^i is diagonalized in the ESR.

空间高速光通信基带调制信号产生与相位同步方法研究

高速调制基带信号的高质量产生与相位精确同步是实现空间光通信测距的关键技术。传统采用FPGA或数字信号处理器(DSP)与高速数模转换器(DAC)的实现方法,存在相位同步精度低、硬件实现复杂度高等缺点。该文提出一种高速光通信基带信号产生与相位同步方法,设计了相位闭环动态控制环路,通过实时调整高速信号发射时钟相位,可实现I,Q高速基带信号相位与外部参考时钟相位的确定性关系。实验结果表明:正交相移键控(QPSK)光调制信号码速率为5 Gbit/s时,相位同步精度小于2 ps,误差矢量幅度(EVM)小于8%;5 Gbit/s光通信速率误码率为10^(–7),接收灵敏度优于–47 dBm,测距精度优于2 mm。与传统方法相比,其灵敏度与测距精度均得到明显改善。

湖北黄梅宽频带形变观测仪与地震计数据融合分析

本文分析对比了湖北黄梅地震监测站宽频带地倾斜仪、地应变仪和地震计观测的同震响应的频谱和震相特征,结果表明两类定点形变仪对地震波具有高度灵敏性,并且相较于倾斜仪,应变仪的频谱更贴近于地震计。因此尝试利用应变地震波确定地震震级,从而收集了2021—2024年全球震级M≥5.0具有同震响应的共计372次有效地震,并基于中国地震台网中心发布的地震目录,用最小二乘法得到了应变震级公式。

基于虚拟功角功率控制的VSG增强功率解耦策略

虚拟同步机可提升“双高”电力系统惯性,但其存在的固有功率强耦合会产生功率稳态误差,严重限制变流器功率传输能力,甚至导致系统失稳。为此,该文详细分析VSG功率耦合机理,指出线路阻感比R/X与功角θ是影响功率耦合两大因素,并评估其引起的功率耦合对稳定性影响。然后在虚拟电感控制基础上考虑R/X和θ,提出一种基于虚拟功角的功率控制策略,使用理论公式计算虚拟功角值改进功率环控制,增强了大范围功角情况下功率解耦效果,抑制了无功功率波动,并用幅相运动方程判据评估该系统稳定性。最后,通过理论分析和实验结果验证所提解耦控制策略的有效性。

数量信息不能引发符号的空间表征

该研究为了考察数量信息能否独立引发符号的空间表征,采用若干面积不等的圆和点数不同的点阵作为实验刺激,让被试用左右手按键,判断圆面积的大小,以及点阵点数的多少。结果发现,无论在面积大小判断任务中,还是在点数数量判断任务中,都没有产生SNARC效应。这说明,单纯的数量信息,并不能引发符号进行空间表征。这一结果也在一定程度上支持了Gevers等人的假设:数字的空间表征,是由数字的顺序性信息决定的,而并非是由其数量信息决定的。