arXiv subjects

Cheng-Jie Wang

Publications and source records attributed to Cheng-Jie Wang.

7 recordsLinked to original sources

arXiv2026

Fast charging of Lipkin-Meshkov-Glick quantum battery

Fast charging is a pivotal and fundamental performance metric in quantum battery (QB) research. Here, we investigate the fast-charging performance of the Lipkin-Meshkov-Glick QB based on shortcuts to adiabaticity (STA). We mainly consider a scenario where the coupling strength between arbitrary two sites in the QB varies sinusoidally over time. We demonstrate that the STA protocol can remarkably enhance the charging efficiency. During the charging cycle, STA drives the periodic evolution of stored energy, coherence relative entropy, and energy fluctuations, and effectively suppresses energy fluctuation magnitude. We reveal that quantum coherence serves as a crucial quantum resource for boosting the charging efficiency of a QB. We analyze the influences of the anisotropy parameter, driving field amplitude and frequency, as well as particle number on the overall battery performance and show that an efficient charging and prominent charging advantages can be realized by modulating of these physical parameters. We further evaluate the energy cost throughout the charging process, and confirm that the maximum energy cost per particle can be reduced via appropriate tuning of driving field parameters. Our results offer valuable insights into the optimal design and practical implementation of high-efficiency fast-charging QB.

quant-ph↗

arXiv2025

Ergotropy in Quantum Batteries

Ergotropy--a key figure of merit for quantum battery (QB) performance--plays a crucial role. However, the dynamics and physical mechanisms governing ergotropy evolution remain open challenges. Here, we investigate the ergotropy of a general QB model and find that the charging process is accompanied by the variation and inversion of the energy level populations. In the absence of population inversion, the ergotropy is fully consistent with coherent ergotropy; in local and global population inversion, it is determined by both coherent and incoherent ergotropy. Via random sampling of quantum states and Hamiltonians, we show that coherence and the participation ratio enhance coherent ergotropy, whereas incoherent ergotropy--whether enhanced, unchanged, or suppressed--depends on diagonal entropy, the participation ratio, and energy level population ordering. We demonstrate that the ergotropy lower bound is incoherent ergotropy, the upper bound is the QB stored energy, and enhanced QB purity suppresses locked energy and boosts charging efficiency. Furthermore, we use the Tavis-Cummings (TC) and Jaynes-Cummings (JC) batteries as paradigms to validate our findings. Our work elucidates ergotropy underlying mechanisms in general QBs and establishes a rigorous framework for optimizing ergotropy and charging efficiency, paving the way for high-performance quantum energy-storage devices.

quant-ph↗

arXiv2025

Resonant Singly Heavy Pentaquarks in the MIT Bag Model: Mass Spectra and Strong Decays

Exploring the limits of color interactions in multiquark states is an important topic. Based on the bag confinement picture of hadrons, we find that for singly heavy pentaquarks, the bag confinement radius precisely falls within the range of color interaction limits provided by lattice QCD, approximately 1.17--1.29$\,\text{fm}$. This leads us to believe that singly heavy pentaquark states have the potential to form resonant states. Inspired by singly heavy baryons, we consider the mirror pentaquarks of singly heavy baryons. Furthermore, we adopt the MIT bag model, taking into account chromomagnetic and color-electric interactions between heavy and strange quarks, to calculate the mass spectrum of singly heavy pentaquarks configured as $qqqQ\bar{q}$ and analyze the stability of their S-wave two-body strong decays. We show that for the singly heavy pentaquark system, the masses are generally about $500\, \text{MeV}$ higher than the corresponding mirror baryon ground state masses, which is consistent with conclusions drawn from chiral methods. We also provide a mass mapping relationship between singly heavy pentaquarks and singly heavy baryons based on light quark flavor symmetry. The analysis of strong decays indicates that these singly heavy pentaquarks are unstable with respect to strong decays, which is consistent with our initial hypothesis.

hep-ph↗

arXiv2024

Spin-wave frequency multiplication by magnetic vortex cores

Frequency multiplication involves generating harmonics from an input frequency, a technique particularly useful for integrating spin-wave devices operating at different frequencies. While topological magnetic textures offer distinct advantages in spin-wave applications, frequency multiplication has not yet been observed in these structures. Here, we study the magnetization dynamics of magnetic vortices formed in micron-sized disks and squares via wide-field magnetic imaging. We found the occurrence of coherent spin-wave harmonics arising from the gyration of vortex cores driven by microwave fields. This phenomenon reveals a universal mechanism where the periodical motion of delta function-like objects such as vortex cores gives rise to a frequency comb. Our results pave the way for creating nanoscale, tunable spin-based frequency multipliers and open new possibilities for frequency comb generation in a variety of systems.

cond-mat.mes-hall↗

arXiv2023

Reciprocating Magnetic Fields in the Pulsar Wind Observed from the Black Widow Pulsar J1720-0534

We report the radio observations of the eclipsing black widow pulsar J1720-0534, a 3.26 ms pulsar in orbit with a low mass companion of mass 0.029 to 0.034 M$_{\odot}$. We obtain the phase-connected timing ephemeris and polarization profile of this millisecond pulsar (MSP) using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), the Green Bank Telescope (GBT), and the Parkes Telescope. For the first time from such a system, an oscillatory polarisation angle change was observed from a particular eclipse egress with partial depolarization, indicating 10-milliGauss-level reciprocating magnetic fields oscillating in a length scale of 5000 km (assuming an orbital inclination angle of 90 degrees) outside the companion's magnetosphere. The dispersion measure variation observed during the ingresses and egresses shows the rapid raising of the electron density in the shock boundary between the companion's magnetosphere and the surrounding pulsar wind. We suggest that the observed oscillatory magnetic fields originate from the pulsar wind outside the companion's magnetosphere.

astro-ph.HE↗

arXiv2022

Three-dimensional structure and formation mechanism of biskyrmions in uniaxial ferromagnets

Magnetic biskyrmions are observed in experiments but their existences are still under debate. In this work, we present the existence of biskyrmions in a magnetic film with tilted uniaxial anisotropy via micromagnetic simulations. We find biskyrmions and bubbles share a unified three-dimensional structure, in which the relative position of two intrinsic Bloch points dominates the two-dimensional topological property in the film middle. The film edge can drive Bloch points and transform bubbles into biskyrmions via the demagnetizing field. This mechanism is found in the formation process of biskyrmions in confined geometry under zero field. Our work clarifies the structure and formation mechanism of biskyrmions, emphasizing the three-dimensional aspect of skyrmion-related nanostructures.

cond-mat.str-el↗

arXiv2020

Single-spin scanning magnetic microscopy with radial basis function reconstruction algorithm

Exotic magnetic structures, such as magnetic skyrmions and domain walls, are becoming more important in nitrogen-vacancy center scanning magnetometry. However, a systematic imaging approach to mapping stray fields with fluctuation of several milliteslas generated by such structures is not yet available. Here we present a scheme to image a millitesla magnetic field by tracking the magnetic resonance frequency, which can record multiple contour lines for a magnetic field. The radial basis function algorithm is employed to reconstruct the magnetic field from the contour lines. Simulations with shot noise quantitatively confirm the high quality of the reconstruction algorithm. The method was validated by imaging the stray field of a frustrated magnet. Our scheme had a maximum detectable magnetic field gradient of 0.86 mT per pixel, which enables the efficient imaging of millitesla magnetic fields.

quant-ph↗