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We demonstrate that in a chiral plasma subject to an external magnetic field, the chiral vortical effect can induce a new type of magnetohydrodynamic instability which we refer to as the {\it chiral magnetovortical instability}. This instability arises from the mutual evolution of the magnetic and vortical fields. It can cause a rapid amplification of the magnetic fields by transferring the chirality of the constituent particles to the cross helicity of the plasma., V1: 7pages, 2 figures

We investigate the finite-temperature quantum chromodynamics (QCD) on a rotating lattice with $N_f=2+1$ staggered fermions and the projective plane boundary condition. We observe a negative rotational rigidity (defined in the main text) and a negative quark spin susceptibility associated with the chiral vortical effect. In contrast to most of the effective model predictions, we find that the chiral condensate decreases and the Polyakov loop increases with imaginary rotation, implying a rotational catalysis of chiral symmetry breaking and confinement by real rotation. We determine the phase boundaries for both chiral and confinement-deconfinement phase transitions on the $\Omega_I$-$T$ plane, where $\Omega_I$ is the imaginary angular velocity., Comment: 17 pages, 7 figures

Rapid rotation may exist in physical systems such as non-central heavy ion collisions and neutron stars. Using functional renormalization group analysis of the quark-meson model, we investigate the effects of real and imaginary rotation on the chiral phase transition. Our results confirm previous studies conducted with other model calculations and shed light on the importance of boundary conditions in the infrared region of the theory., 14 pages, 12 figures

Magnetic field plays a crucial role in various novel phenomena in heavy-ion collisions. We solve the Maxwell equations numerically in a medium with time-dependent electric conductivity by using the Finite-Difference Time-Domain (FDTD) algorithm. We investigate the time evolution of magnetic fields in two scenarios with different electric conductivities at collision energies ranging from $\sqrt{s_\text{NN}}=$ 7.7 to 200 GeV. Our results suggest that the magnetic field may not persist long enough to induce a significant splitting between the global spin polarizations of $\Lambda$ and $\bar{\Lambda}$ at freeze-out stage. However, our results do not rule out the possibility of the magnetic field influencing the spin (anti-)alignment of vector mesons., Comment: Revtex4-2, 7 pages, 2 figures

Within the framework of Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, we extract the global spin polarization of Λ hyperon in $^{108}$Ag+108Ag and $^{197}$ Au+197Au collisions at sNN=2.42–62.4 GeV. We use two different approaches to calculate the Λ polarization Py: approach I is based on equilibrium assumption so that Py is determined by thermal vorticity and approach II assumes a proportional relation between Py and the system's angular momentum in Λ's rest frame. We find that both approaches can describe the experimental data at low energies around a few GeV but only approach I describes well also higher-energy data. This suggests that at higher energies the relativistic effect plays an important role. After taking into such effect properly, the relativity-improved approach II can describe the higher-energy data as well.

Ultra-peripheral heavy-ion collisions (UPC) provide unique opportunities to study processes under strong electromagnetic fields. Highly-charged moving ions carry strong electromagnetic fields that act as fields of photons. The exchange of photons could induce photonuclear and two-photon interactions as well as excite the ions into giant dipole resonances (GDRs) or even higher excitation. The GDRs typically decay by emitting photons and even a single neutron, while high-excited resonances usually decay by emitting two or more photons and/or neutrons. On the other hand, the electromagnetic fields of heavy ions are very strong, so one of the two colliding ions is enforced by the other's electromagnetic field. As a result, the two colliding ions are pushed into opposite directions by the electromagnetic forces, and thus the neutrons emitted from different ions could present a back-to-back correlation. Using a Monte-Carlo simulation implementing the electromagnetic fields as well as the neutron emission from previous measurements or model calculations, we qualitatively demonstrate that the above electromagnetic effect is large enough to be observed in UPC, which would provide a clear means to study the strong electromagnetic fields and its effects., 4 pages, 3 figures

Chiral anomaly and the novel quantum phenomena it induces have been widely studied for Dirac and Weyl fermions. In most typical cases, the Lorentz covariance is assumed and thus the linear dispersion relations are maintained. However, in realistic materials, such as Dirac and Weyl semimetals, the non-linear dispersion relations appear naturally. We develop a kinetic framework to study the chiral anomaly for Weyl fermions with non-linear dispersions by using the methods of Wigner function and semi-classical equations of motion. In this framework, the chiral anomaly is sourced by Berry monopoles in momentum space and could be enhanced or suppressed due to the windings around the Berry monopoles. Our results can help understand the chiral anomaly-induced transport phenomena in non-relativistic systems., Comment: 7 pages, no figure. Published in Chin. Phys. Lett

Within the framework of Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, we extract the global spin polarization of $\Lambda$ hyperon in $^{108}$Ag + $^{108}$Ag and $^{197}$Au + $^{197}$Au collisions at $\sqrt{s_{\rm NN}} = 2.42 - 62.4$ GeV. We use two different approaches to calculate the $\Lambda$ polarization $P_y$: approach I is based on equilibrium assumption so that $P_y$ is determined by thermal vorticity and approach II assumes a proportional relation between $P_y$ and the system's angular momentum in $\Lambda$'s rest frame. We find that both approaches can describe the experimental data at low energies around a few GeV but only approach I describes well also higher-energy data. This suggests that at higher energies the relativistic effect plays an important role. After taking into such effect properly, the relativity-improved approach II can describe the higher-energy data as well., Comment: V3: 6 pages, 5 figures. Published version

High-energy heavy-ion collisions generate extremely strong magnetic field which plays a key role in a number of novel quantum phenomena in quark-gluon plasma (QGP), such as the chiral magnetic effect (CME). However, due to the complexity in theoretical modellings of the coupled electromagnetic fields and the QGP system, especially in the pre-equilibrium stages, the lifetime of the magnetic field in the QGP medium remains undetermined. We establish, for the first time, a kinetic framework to study the dynamical decay of the magnetic field in the early stages of a weakly coupled QGP by solving the coupled Boltzmann and Maxwell equations. We find that at late times a magnetohydrodynamical description of the coupled system emerges. With respect to realistic collisions at RHIC and the LHC, we estimate the residual strength of the magnetic field in the QGP when the system start to evolve hydrodynamically., 6 pages and 3 figures

We give an introduction to the phase structure of QCD matter under rotation based on effective four-fermion models. The effects of the magnetic field on the rotating QCD matter are also explored. Recent developments along these directions are overviewed, with special emphasis on the chiral phase transition. The rotational effects on pion condensation and color superconductivity are also discussed., Comment: 29 pages, 20 figures. Submitted to Lecture Notes in Physics book "Strongly Interacting Matter under Rotation" on October 16, 2020

We study the global polarizations of $\Lambda$, $\Xi^-$, and $\Omega^-$ hyperons in noncentral Au+Au collisions at $\sqrt{s_\mathrm{NN}}=$ 7.7-200 GeV. We highlight the importance of effect of decay feeddown to the measured global polarization. With the decay contributions taken into account, the global polarization ordering $P_{\Omega^-} > P_{\Xi^-} > P_\Lambda$ can be naturally explained, which is consistent with the observation recently reported from the STAR experiment from Au+Au collisions at 200 GeV. We also extend our calculations to predict expectations from the RHIC-BES II data., Comment: 4 pages, 2 figures, contribution to 19th International Conference on Strangeness in Quark Matter (SQM2021)

We develop a covariant kinetic theory for massive fermions in a curved spacetime and an external electromagnetic field based on quantum field theory. We derive four coupled semi-classical kinetic equations accurate to , which describe the transports of particle number and spin degrees of freedom. The relationship with chiral kinetic theory is discussed. As an application, we study spin polarization in the presence of finite Riemann curvature and an electromagnetic field in both local and global equilibrium states.

Heavy ion collisions generate strong fluid vorticty in the produced hot quark-gluon matter which could in turn induce measurable spin polarization of hadrons. We review recent progress on the vorticity formation and spin polarization in heavy ion collisions with transport models. We present an introduction to the fluid vorticity in non-relativistic and relativistic hydrodynamics and address various properties of the vorticity formed in heavy ion collisions. We discuss the spin polarization in a vortical fluid using the Wigner function formalism in which we derive the freeze-out formula for the spin polarization. Finally we give a brief overview of recent theoretical results for both the global and local spin polarization of $\Lambda$ and $\bar\Lambda$ hyperons., Comment: V2: 29 pages, 15 figures, published in Lecture Notes in Physics vol.987, "Strongly Interacting Matter under Rotation", page 281-308

We develop a theoretical framework to study the feed-down effect of higher-lying strange baryons on the spin polarization of the $\Lambda$ hyperon. In this framework, we consider two-body decays through strong, electromagnetic, and weak processes and derive general formulas for the angular distribution and spin polarization of the daughter particle by adopting the helicity formalism. Using the realistic experimental data as input, we explore the feed-down contribution to the global and the local $\Lambda$ polarizations and find that such a contribution suppresses the primordial $\Lambda$ polarization, which is not strong enough to resolve the discrepancy between the current theoretical and the experimental results on the azimuthal-angle dependence of $\Lambda$ polarization. Our paper may also be useful for the measurement of spin polarization of baryons heavier than $\Lambda$ (e.g., $\Xi^-$) in future experiments., Comment: 12 pages, 9 figures

We revisit the condensation scenario of charged pions in external magnetic field and rotation, which was first considered by Y. Liu and I. Zahed. Based on the Ginzburg-Landau analysis of the Nambu--Jona-Lasinio model, we find that the charged-pion condensation takes place only when both a strong coupling constant and negatively large baryon chemical potential are applied. Besides, our numerical calculation shows that the chiral restoration induced by the interplay between magnetic field and rotation (i.e., the rotational magnetic inhibition) interrupts the formation of the charged-pion condensate. This suggests that the analysis of such condensation requires a careful treatment of the inner structure of pions, which was not taken into account before. We also discuss the underlying physical mechanism of our finding and the indication of charged-rho condensation., Comment: V2: 10 pages, 4 figures

We develop a theoretical framework to study the feed-down effect of higher-lying strange baryons on the spin polarization of the $��$ hyperon. In this framework, we consider two-body decays through strong, electromagnetic, and weak processes and derive general formulas for the angular distribution and spin polarization of the daughter particle by adopting the helicity formalism. Using the realistic experimental data as input, we explore the feed-down contribution to the global and the local $��$ polarizations and find that such a contribution suppresses the primordial $��$ polarization, which is not strong enough to resolve the discrepancy between the current theoretical and the experimental results on the azimuthal-angle dependence of $��$ polarization. Our paper may also be useful for the measurement of spin polarization of baryons heavier than $��$ (e.g., $��^-$) in future experiments., 12 pages, 9 figures

The isobaric collisions of $^{96}_{44}$Ru + $^{96}_{44}$Ru and $^{96}_{40}$Zr + $^{96}_{40}$Zr have recently been proposed to discern the charge separation signal of the chiral magnetic effect (CME). In this article, we employ the string melting version of a multiphase transport model to predict various charged-particle observables, including $dN/d\eta$, $p_T$ spectra, elliptic flow ($v_2$), and particularly possible CME signals in Ru + Ru and Zr + Zr collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV. Two sets of the nuclear structure parametrization have been explored, and the difference between the two isobaric collisions appears to be small, in terms of $dN/d\eta$, $p_T$ spectra, and $v_2$ for charged particles. We mimic the CME by introducing an initial charge separation that is proportional to the magnetic field produced in the collision, and study how the final-state interactions affect the CME observables. The relative difference in the CME signal between the two isobaric collisions is found to be robust, insensitive to the final-state interactions., Comment: 8 pages, 10 figures; final published version

MeV-scale magnetic fields in the interiors of magnetars suppress the pairing of neutrons and protons in the $S$-wave state. In the case of a neutron condensate the suppression is the consequence of the Pauli-paramagnetism of the neutron gas, i.e., the alignment of the neutron spins along the magnetic field. The proton $S$-wave pairing is suppressed because of the Landau diamagnetic currents of protons induced by the field. The Ginzburg-Landau and BCS theories of the critical magnetic fields for unpairing are reviewed. The macrophysical implications of the suppression (unpairing) of the condensates are discussed for the rotational crust-core coupling in magnetars and the neutrino-dominated cooling era of their thermal evolution., Comment: 10 pages, 4 figures, Proceedings of "Compact Stars in the QCD phase diagram V", 23-27 May 2016 GSSI and LNGS, L'Aquila, Italy

We present a theoretical study of the finite-temperature Kosterlitz-Thouless (KT) and vortex-antivortex lattice (VAL) melting transitions in two-dimensional Fermi gases with $p$- or $d$-wave pairing. For both pairings, when the interaction is tuned from weak to strong attractions, we observe a quantum phase transition from the Bardeen-Cooper-Schrieffer (BCS) superfluidity to the Bose-Einstein condensation (BEC) of difermions. The KT and VAL transition temperatures increase during this BCS-BEC transition and approach constant values in the deep BEC region. The BCS-BEC transition is characterized by the non-analyticities of the chemical potential, the superfluid order parameter, and the sound velocities as functions of the interaction strength at both zero and finite temperatures; however, the temperature effect tends to weaken the non-analyticities comparing to the zero temperature case. The effect of mismatched Fermi surfaces on the $d$-wave pairing is also studied.

An economical magnetocardiogram (MCG) system is built in our laboratory. It mainly consists of a MCG data acquisition stage equipped with two high-Tc superconducting quantum interference device (SQUID) magnetometers, a data processing stage with digital filtering and a one-layer μ-metal magnetically shielded room in conjunction with a high-Tc SQUID based active compensation. Experimental results show that a noise level of pico-tesla in MCG profiles, which is necessary for clinical applications, may be achieved with the system. Moreover, stable and convenient operations of the system are demonstrated with simulating MCG measurements.

An adaptive filter based on Data-Reusing Least-Mean-Square algorithm has been proposed and applied in magnetocardiography (MCG) to suppress ambient noise. Numerical simulation studies indicate that the adaptive filter is a powerful noise suppresser for correlated interferences, especially for those with amplitude changing and time delay. Also the filter has a wide frequency bandwidth. With this filter, the signal-to-noise ratio of an MCG is improved to the intrinsic noise level. The periodic average method for further improvement of the noise level in MCG is also discussed.

A modulation principle and method, the gate-voltage-controlled mode-guiding switching/mode-cutoff mechanism, is proposed and numerically investigated to achieve the modulation/attenuation function. The propagating attenuation of the graphene 2D waveguide as a function of the Fermi level of the cladding is analyzed. Different modes with low or high attenuations in a wide attenuation range have been observed. The proposed structure avoids the patterning on graphene or substrate, thus diminishing the energy scattering on the edges. It also has the advantages of large modulation depth/attenuation range, wide bandwidth, and sub-micrometer chip-length with a nanoscale lateral section, which is promising for future graphene-based integrated photonic devices.

Coastal diatoms are often exposed to both petroleum-derived hydrocarbon pollution and eutrophication. How these exposures influence on algal biomass, lifetime, and nutritional value are unknown. To examine a more accurate risk assessment of the pollutants on the role of diatoms in coastal ecosystem functions, Conticribra weissflogii was maintained at different concentrations of nitrate (N) and/or water-soluble fractions of No.0 diesel oil (WSF). Algal density, cell growth cycle, protein, chlorophyll a, superoxide dismutase (SOD) activity, and malonaldehyde (MDA) were determined for the assessment of algal biomass, lifetime, nutritional value, photosynthesis and respiration, antioxidant capacity, and lipid peroxidation, respectively.When N addition was combined with WSF pollution, the cell growth cycles were shortened by 27-44%; SOD activities were decreased by 1-64%; algal density, the concentrations of chlorophyll a, protein, and MDA were varied between 38 and 310%, 62 and 712%, 4 and 124%, and 19 and 233% of the values observed in N addition experiments, respectively. Coastal ecosystem functions were severely weakened by N and WSF additions, and the influence was increased in the order: NWSFWSF+N. Thus, the simultaneous monitoring of N and WSF was necessary for the risk assessment of petroleum-derived hydrocarbon on coastal ecosystem functions.

The fluorescent decays and spectra of pump power density dependent emission demonstrated that the excitation power density was enhanced in Rh640 dye solution containing scattering nanoparticles. Lasing in disordered scattering medium with low threshold, narrow bandwidth, and short duration was observed. The mechanism of this enhancement, together with the lasing properties of low threshold and narrow bandwidth, was discussed.

Diatoms dominate phytoplankton communities in the well-mixed coastal and upwelling regions. Coastal diatoms are often exposed to both aquaculture pollution and eutrophication. But how these exposures influence on coastal ecosystem functions are unknown. To examine these influences, a coastal centric diatom, Conticribra weissflogii was maintained at different concentrations of nitrate (N) and/or oxytetracycline (OTC). Algal density, cell growth cycle, protein, chlorophyll a, superoxide dismutase (SOD) activity, and malonaldehyde (MDA) were determined for the assessment of algal biomass, lifetime, nutritional value, photosynthesis and respiration, antioxidant capacity, and lipid peroxidation, respectively. When N addition was combined with OTC pollution, the cell growth cycles were shortened by 56-73%; algal density, SOD activities, the concentrations of chlorophyll a, protein, and MDA varied between 73 and 121%, 19 and 397%, 52 and 693%, 19 and 875%, and 66 and 2733% of the values observed in N addition experiments, respectively. According to P-value analysis, the influence of OTC on algal density and SOD activity was not significant, but the effect on cell growth cycle, protein, chlorophyll a, and MDA were significant (P

The interaction of the electrons with the phonons in GaAs/AlGaAs quantum wells, quantum well wires, and quantum well boxes has been studied by meansuring their time resolved photoluminescence (PL) spectra. In the quantum well (QW) system, relaxation time of the electron energy of the narrower well is shorter than that of the wider well. It is attributed to the stronger interaction of the electrons with the interface mode phonons. In the QW wires and QW boxes, the shortening of the relaxation time is obvious. It is due to the stronger electron-phonon interaction caused by the reduction of screening effect. Our experiments also demonstrated the incident laser intensity dependence of the relaxation time.

We propose and numerically simulate a nanoscale electro-optic (EO) switch based on a metal-insulator-metal structure composed of a strip waveguide and two side-coupled cavities filled with an EO material of 4-dimethyl-amino-N-methyl-4-stilbazolium tosylate, using the finite difference time domain method. It is found that the structure can be operated as an EO switch at a wavelength of 945 nm, with a modulation depth of 27 dB, a half-wave voltage of 5.3 V and a switching time of about 50 ps.

An electro-optical switch based on a plasmonic T-shaped waveguide structure with a double-teeth-shaped waveguide filled with 4-dimethylamino-N-methyl-4-stilbazolium tosylate is proposed and numerically investigated. The Finite-difference time domain simulation results reveal that the structure can operate as a circuit switch by controlling the external voltages V1 and/or V2. The proposed structure can also operate as a variable optical attenuator, which can continuously attenuate tie power of a light beam from 6 dB to 30 dB by an external electrical field. The structure is of small size of a few hundred nanometers. Our results may open a possibility to construct nanoscale high-density photonic integration circuits.

A high-resolution plasmonic refractive-index sensor based on a metal-insulator-metal structure consisting of a straight bus waveguide and a resonator waveguide is proposed and numerically simulated by using the finite difference time domain method under a perfectly matched layer absorbing boundary condition. Both analytic and simulated results show that the resonant wavelengths of the sensor have a linear relationship with the refractive index of material under sensing. Based on the relationship, the refractive index of the material can be obtained from the detection of one of the resonant wavelengths. The resolution of refractive index of the nanometeric plasmonic sensor can reach as high as 10−6, giving the wavelength resolution of 0.01 nm. It could be applied to highly-resolution biological sensing.

A full-duplex radio-over-fiber system using frequency-twelvefold optical millimeter-wave based on external modulation via a Mach–Zehnder modulator is proposed and analyzed theoretically. The simulation results show that the power penalties for both the downstream and upstream signals are less than 0.5 dB. In this scheme, the configuration of a base station is simplified without laser, while the frequency of local oscillator signal is largely reduced due to the frequency-twelvefold millimeter-wave technique. The cost of the new system is largely reduced.

Compared with the photonic crystal (PC) structures composed of Si circular, the PC structrures composed of triangular lattice of air holes in a dielectric slab are more easily fabricated and integrated. The tunability of directional band gap in a two-dimensional photonic crystal of air holes in a semiconductor matrix is demonstrated numerically, using the plane wave expansion calculation. Numerical simulations show that the photonic crystal band gaps are modulated by nematic liquid crystals infiltrated in the air holes. Then the band gap can be controlled easily under the influence of the external electric field. So the results can serve as a field-sensitive polarizer. These results are in agreement with that of Liu. However, the tunable field-sensitive polarizer based on the phenylacetylene liquid crystals instead of 5CB liquid crystals has the wider frequency range. Moreover, the transmission spectrum of the photonic crystal infiltrated by liquid crystal is analyzed, using finite difference time domain (FDTD) method. Numerical simulations show that the shift of the spectrum modulated by liquid crystal can be used to design a novel switch.

How to extract the magnetocardiography (MCG) signals from the background noises and attenuate the noise is the key element of MCG signal processing. From the aspect of software technique, a new adaptive algorithm is proposed to suppress the environmental magnetic noise of MCG in this paper. The propo sed algorithm is called improved complementary pair normalized least mean square algorithm. This adaptive structure is designed for MCG. This new algorithm prov ides the faster convergence speed and smaller steady-state error. In order to test the performance of this algorithm, the result of the simulated experiment and real MCG signal is analyzed. This method bring about the effective noise atten uation. Meanwhile, this algorithm is suitable for noise cancellation of other non-stationary signals.

Luminescence spectra, picosecond decay and Fourier transform infrared spectroscopy measurements show that there are two independent emission mechanisms in the spontaneously oxidized porous Si. One is determined by the quantum confinement effect , the other is produced by the oxidation.

The initial dynamics of photogenerated carriers in a-Si:H/a-SiNx:H multilayers has been investigated with time-resolved laser spectroscopy. The mechanisms of thermalization and recombination of these carriers are analysed. The results also reveal that the decay time cutoff, the mobility edge and the band-tail width vary non-monotonously with respect to nitrogen content with a turning point near x = 0.85, which may result from the changes of the internal electric field and the structure of multilayer with nitrogen content.