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Dynamic crossover in [VIO^(2+)][Tf_(2)N-]_(2) ionic liquid

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Chinese physics B 2021年第1期30卷 374-379页

作者：任淦 departments of physics&key laboratory of photonic and optical detection in civil aviation Civil Aviation Flight University of ChinaGuanghan 618307China

Ionic liquids usually behave as fragile liquids,and the temperature dependence of their dynamic properties obeys supper-Arrhenius law.In this work,a dynamic crossover is observed in([VIO^(2+)][Tf_(2)N-]_(2)) ionic liquid at the temperature of 240-800 K.The diffusion coefficient does not obey a single Arrhenius law or a Vogel-Fulcher-Tammann(VFT) relation,but can be well fitted by three Arrhenius laws or a combination of a VFT relation and an Arrhenius law.The origin of the dynamic crossover is analyzed from correlation,structure,and thermodynamics.Ion gets a stronger backward correlation at a lower temperature,as shown by the fractal dimension of the random walk.The temperature dependence function of fractal dimension,heterogeneity order parameter,and thermodynamic data can be separated into three regions similar to that observed in the diffusion coefficient.The two crossover temperatures observed in the three types of data are almost the same as that in diffusion coefficient fitted by three Arrhenius laws.The results indicate that the dynamic crossover of[VIO2+][Tf2 N-]2 is attributed to the heterogeneous structure when it undergoes cooling.

关键词： ionic liquids dynamic crossover heterogeneity order parameter fractal dimension fragile

Majorana-Kondo interplay in a Majorana wire-quantum dot system with ferromagnetic contacts

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Communications in Theoretical physics 2021年第3期73卷 148-155页

作者：羊富彬 Department of physics&key laboratory of photonic and optical detection in civil aviation Civil Aviation Flight University of ChinaGuanghan 618307China

We consider a single-level quantum dot(QD)and a topological superconducting wire hosting Majorana bound states at its ends.By the equation of motion method,we give the analytical Green’s function of the QD in the noninteracting and the infinite interacting case.We study the effects of QD energy level and the spin polarization on the density of states(DOS)and linear conductance of the system.In the noninteracting case,the DOS resonance shifts with the change of energy level and it shows bimodal structure at large spin polarization strength.In the infinite interacting case,the up-spin linear conductance first increases and then decreases with the increase of spin polarization strength,but the down-spin is stable.However,the DOS shows a splitting phenomenon in the large energy level with the increase of spin polarization strength.This provides an interesting way to explore the physical properties of such spin dependent effect in the hybrid Majorana QD systems.

关键词： Majorana system Kondo effect spin polarized

Phase-and spin-dependent manipulation of leakage of Majorana mode into double quantum dot

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Chinese physics B 2021年第7期30卷 636-640页

作者：羊富彬任淦谢林果 Department of physics and key laboratory of photonic and optical detection in civil aviation Civil Aviation Flight University of ChinaGuanghan 618307China

We present a phase-and spin-dependent manipulation of leakage of a Majorana mode into a double quantum dot.We study the density of states(DOS)to show the effect of phase change factor on the Majorana leakage into(out)of a double quantum dot.The DOS is derived from the Green's function of the quantum dot by the equation of motion method,and exhibits a formant structure whenφ=0,2πand a resonance shape whenφ=0.5πand 1.5π.Also,it changes more strongly under the spin-polarized coefficient than the non-polarized lead.Such a theoretical model can be modified to explore the spin-dependent effect in the hybrid Majorana quantum dot system.

关键词： spin-dependent coupling Majorana bound states double quantum dots

Supercooled liquids analogous fractional Stokes–Einstein relation in NaCl solution above room temperature

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Chinese physics B 2019年第7期28卷 381-388页

作者：任淦田时开 departments of physics & key laboratory of photonic and optical detection in civil aviation Civil Aviation Flight University of China

The Stokes–Einstein relation D^T/η and its two variants D~τ-1 and D^T/τ follow a fractional form in supercooled liquids, where D is the diffusion constant, T the temperature,η the shear viscosity, and τ the structural relaxation time.The fractional Stokes–Einstein relation is proposed to result from the dynamic heterogeneity of supercooled liquids.In this work, by performing molecular dynamics simulations, we show that the analogous fractional form also exists in sodium chloride(NaCl) solutions above room temperature.D~τ-1 takes a fractional form within 300–800 K;a crossover is observed in both D^T/τ and D^T/η.Both D^T/τ and D^T/η are valid below the crossover temperature Tx,but take a fractional form for T > Tx.Our results indicate that the fractional Stokes–Einstein relation not only exists in supercooled liquids but also exists in NaCl solutions at high enough temperatures far away from the glass transition point.We propose that D^T/η and its two variants should be critically evaluated to test the validity of the Stokes–Einstein relation.

关键词： sodium chloride solutions supercooled liquids molecular dynamics Stokes–Einstein relation

Parameter accuracy analysis of weak-value amplification process in the presence of noise

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Chinese physics B 2021年第6期30卷 385-389页

作者：邱疆冬李兆雪谢林果罗兰何宇任昌亮张志友杜惊雷 College of physics Sichuan UniversityChengdu 610064China key laboratory of photonic and optical detection in civil aviation and Atmospheric Lidar Institute Civil Aviation Flight University of ChinaGuanghan 618300China Center for Nanofabrication and System Integration Chongqing Institute of Green and Intelligent TechnologyChinese Academy of SciencesChongqing 400714China

We theoretically introduce the statistical uncertainty of photon number and phase error to discuss the precision of parameters to be measured based on weak measurements. When the photon counting scheme is used, we discuss the relative accuracy of the system in the presence of phase error by using the orthogonal and nonorthogonal pre-and postselected states, respectively. When using the measurement scheme of pointer shift, we discuss the measurement accuracy in the presence of phase error, pointer resolution, and statistical uncertainty. These results give a guide way to get the smallest relative precision and deepen our understanding about weak measurement.

关键词： weak measurement quantum measurement accuracy analysis