arXiv subjects

Yan-Ling Li

Publications and source records attributed to Yan-Ling Li.

At least 19 recordsLinked to original sources

arXiv2026

Reversible fully spin polarization in strain-engineered two-dimensional fully compensated magnets

Achieving controllable spin polarization and its reversal in symmetry-compensated magnets. Here we demonstrate, using symmetry analysis and a minimal tight-binding model, that uniaxial strain removes these constraints by inducing inequivalence between magnetic sublattices in two-dimensional (2D) system, driving an altermagnetic (AM) state into a fully compensated ferrimagnetic (fFIM) state and enabling fully spin polarization. Furthermore, strain along orthogonal directions gives rise to two energetically degenerate fFIM states with opposite spin polarization, enabling reversible spin switching. More importantly, the two symmetry-related fFIM states can be regarded as distinct ferroelastic variants, suggesting that this model or mechanism can be extended to ferroelastic fFIM systems. The generality of this mechanism is confirmed by combining spin-group analysis, first-principles calculations, and Boltzmann transport theory in representative candidates, including AM Mn$_2$SeO and ferroelastic fFIM V$_2$SO. Our results reveal a universal symmetry-driven framework for strain-controlled and -reversible fully spin-polarized transport and identify strain-engineered AM and ferroelastic fFIM systems as a promising platform for volatile and nonvolatile spintronic applications.

cond-mat.mtrl-sci↗

arXiv2026

From Independent to Joint: Enhancing Quantum Phase and Correlation Factor Estimation by Squeezed Reservoir Engineering

High-precision quantum parameter estimation is fundamental to the advancement of quantum metrology. Although reservoir engineering provides a powerful approach to improve estimation by tailoring system-environment interactions, the role of the squeezing phase and correlations arising from the sequential utilization of the same squeezed reservoir remains inadequately explored. In this work, we employ a correlated squeezed-thermal reservoir to enhance the precision of estimating the phase parameter $\phi$ and the correlation factor $\mu$, both individually and simultaneously. We show that the squeezing phase $\Phi$ is crucial for achieving quantum-enhanced precision, with optimal phase-matching conditions that depend strongly on $\mu$. Specifically, we derive the near-optimal phase-matching relations aimed at maximizing the quantum Fisher information (QFI) for both $\phi$ and $\mu$, as well as minimizing the total variance $\Delta_{\rm sim}$ in joint estimation. Furthermore, we show that the joint estimation variance is dominated by $F_{\phi}$, which motivates our search for the phase-matching conditions that minimize $\Delta_{\text{sim}}$. Through the ratio $R$ of variances, we demonstrate that joint estimation conserves quantum resources and maintains high precision when the squeezing phase is optimized for $F_{\phi}$, despite the inherent incompatibility of the parameters. These findings provide practical insights into reservoir engineering strategies for high-precision quantum sensing and information processing.

quant-ph↗

arXiv2026

Resource-Efficient Teleportation of High-Dimensional Quantum Coherence via Initial Phase Engineering

High-dimensional quantum systems leverage an expanded Hilbert space to enhance resilience against decoherence and noise. However, standard quantum teleportation is fundamentally limited by the quadratic growth of measurement complexity and high classical communication overhead, requiring the resolution of $d^2$ Bell states and $2\log_2 d$ classical bits. In this study, we propose a resource-efficient high-dimensional coherence teleportation (REHDCT) protocol. By designing $d$ sets of specialized positive operator-valued measure (POVM) bases, our protocol achieves a 50\% reduction in classical communication by utilizing one of the $d$ designed POVM sets, which effectively scales the measurement complexity from $O(d^2)$ to $O(d)$. Furthermore, we demonstrate that by utilizing initial phase engineering to align the target qudit with the measurement basis, theoretically perfect teleportation of quantum coherence can be achieved for arbitrary qudit states. A quantitative robustness analysis reveals that the protocol remains highly resilient to operational errors, maintaining an efficiency above 99.6\% even under a 0.1 rad phase deviation for $d=16$. Our analysis under various noise models (amplitude damping, phase flip, depolarizing, and dit-flip) confirms that high-dimensional systems exhibit an expanding quantum advantage window as dimensionality increases. Notably, under dit-flip noise, perfect coherence teleportation can be restored through the optimal selection of the POVM basis. These findings establish REHDCT as a practical, hardware-friendly framework for resource-efficient quantum communication in future high-dimensional networks.

quant-ph↗

arXiv2025

Pressure and doping control of magnetic order and metallization in Ruddlesden-Popper La2NiO4

The discovery of superconductivity in multilayer nickelates under pressure has intensified interest in understanding the magnetic and electronic properties of Ruddlesden-Popper nickelates. Using density functional theory with Hubbard corrections, we investigate the magnetic ground state, electronic structure evolution under pressure, and Sr-doping effects in La$_2$NiO$_4$. We find that at ambient pressure, tetragonal La$_2$NiO$_4$ exhibits G-type antiferromagnetic order with negligible interlayer magnetic coupling. Under hydrostatic pressure, the system undergoes a continuous insulator-metal transition at ~50 GPa while maintaining robust magnetic order up to 75 GPa, contrasting sharply with the rapid magnetic suppression in La$_3$Ni$_2$O$_7$. Sr doping induces a systematic evolution from G-type to A-type, to striped antiferromagnetic orders, and eventually to ferromagnetic order, accompanied by metallization. Furthermore, LaSrNiO$_4$ displays weak charge and orbital orders. These results reveal the unique pressure and doping effects of single-layer nickelates and provide insights into the magnetic mechanisms underlying nickelate superconductivity.

cond-mat.supr-con↗

arXiv2025

Two-dimensional non-van der Waals niobium nitride nanosheets with high-temperature two-gap superconductivity

The exploration of the superconductivity in two-dimensional materials has garnered significant attention due to their promising low-power applications and fundamental scientific interest. Here, we report some novel stable non-van der Waals Nb$_x$N$_{x+1}$ ($x$ = 1-4) monolayers derived from the NbN bulk exfoliated along the (001) plane, as identified through first-principles calculations. Among these monolayers, Nb$_2$N$_3$, which crystallizes in the $P \overline{6} m2$ symmetry, stands out with an exceptional superconducting transition temperature of 77.8 K, setting a new high-$T_c$ benchmark for two-dimensional transition metal nitrides and binary compounds. Our detailed analysis reveals that the strong superconductivity in Nb$_2$N$_3$ is driven by phonon modes dominated by N vibrations, with significant electron-phonon coupling contributions from N-$p$ and Nb-$d$ electronic states. Using the anisotropic Migdal-Eliashberg framework, we further determine the two-gap nature of the superconductivity in the Nb$_2$N$_3$ monolayer, characterized by pronounced electron-phonon coupling and anisotropic energy gaps. These results advance our understanding of superconductivity in 2D transition metal nitride and highlight their potential for nanoscale superconducting applications.

cond-mat.supr-con↗

arXiv2025

Robust cross-chain surface interstitial electronic states and doping-enhanced superconductivity in monolayer $M_2$N ($M$= Ti, Zr, Hf) electrides

The exploration of electrides holds great promise for advancing both fundamental physics and chemistry, owing to their unique characteristics arising from loosely bound interstitial anionic electrons. Here we report a class of cross-chain electrides, distinguished by two distinct anionic electron subchannels forming alternating chains in real space. Through structural symmetry analysis and first-principles calculations, we identify two-dimensional $M_2$N ($M$ = Ti, Zr, Hf) materials as prototypical systems exhibiting these unique features. The anionic electron channels on the upper and lower surfaces of these materials display a vertically alternating pattern, with their projected bands revealing momentum-dependent splitting behavior in the reciprocal space, protected by a crystal symmetry operation $\mathcal{O}$. Notably, the cross-chain electride characteristic in the $M_2$N monoalyers is independent of the layer number and remains robust on the upper and lower surfaces of layered structures, presenting a pronounced and robust surface interstitial electronic state. Additionally, we have explored the superconductivity of these systems, and found that both Ti$_2$N and Zr$_2$N are intrinsic superconductors with superconducting transition temperatures below 1.0 K. Further results show that appropriate hole doping can significantly enhance their superconducting transition temperatures and can induce the Hf$_2$N monolayer to exhibit superconductivity. Our findings provide valuable insights into the design and tuning of novel electrides with enhanced superconducting properties, offering another pathway for deeply understanding the interplay between electride behavior and superconductivity in novel materials.

cond-mat.supr-con↗

arXiv2024

Dual Role of Squeezed-Reservoir in Quantum Phase Synchronization: Boosting and Blockade

This study explores the dual role of a squeezed reservoir in controlling the quantum phase synchronization of a driven two-level system. We first demonstrate, through a Liouvillian eigen-spectrum analysis, that the squeezed reservoir can induce a stable limit cycle, transforming the passive TLS into a genuine self-sustained oscillator. This enables a qualitative transition from a weak ``forced response" to a robust, high-quality synchronization (or entrainment). This enhancement is characterized not only by a greater degree of phase locking but also by an increased frequency selectivity, manifested as a narrower Arnold tongue. More strikingly, we reveal that the squeezing angle acts as a control parameter to actively suppress synchronization. By tuning this angle, the reservoir can drive the system into a classical mixed state, inducing a quantum synchronization blockade via the quenching of steady-state coherence. Our findings establish squeezed-reservoir engineering as a versatile strategy for actively modulating quantum synchronization, with feasible implementations in circuit quantum electrodynamics.

quant-ph↗

arXiv2024

Protecting three-dimensional entanglement from correlated amplitude damping channel

Quantum entanglement is a crucial resource in quantum information processing, and protecting it against noise poses a significant challenge. This paper introduces two strategies for preserving qutrit-qutrit entanglement in the presence of correlated amplitude damping (CAD) noise: weak measurement (WM) and environment-assisted measurement (EAM), both combined with quantum measurement reversal (QMR). Two prototypical classes of three-dimensional entangled states are examined. The findings demonstrate that while the WM+QMR method can partially retain entanglement, the EAM+QMR approach is more effective at protecting entanglement as well as enhancing success probabilities, particularly for specific qutrit-qutrit entangled states. Additionally, we thoroughly discuss the impact of correlation effects on entanglement protection and the enhancement of success probability. Our results provide valuable insights into defending high-dimensional entanglement from CAD noise, thus offering practical solutions for the advancement of quantum information technologies.

quant-ph↗

arXiv2023

Enhanced high-dimensional teleportation in correlated amplitude damping noise by weak measurement and environment-assisted measurement

High-dimensional teleportation provides various benefits in quantum networks and repeaters, but all these advantages rely on the high-quality distribution of high-dimensional entanglement over a noisy channel. It is essential to consider correlation effects when two entangled qutrits travel sequentially through the same channel. In this paper, we present two strategies for enhancing qutrit teleportation in correlated amplitude damping (CAD) noise by weak measurement (WM) and environment-assisted measurement (EAM). The fidelity of both approaches has been dramatically improved due to the probabilistic nature of WM and EAM. We have observed that the correlation effects of CAD noise result in an increase in the probability of success. A comparison has demonstrated that the EAM scheme usually outperforms the WM scheme in regard to fidelity. Our research expands the capabilities of WM and EAM as quantum techniques to combat CAD noise in qutrit teleportation, facilitating the development of advanced quantum technologies in high-dimensional systems.

quant-ph↗

arXiv2023

Classical-driving-assisted quantum synchronization in non-Markovian environments

We study the quantum phase synchronization of a driven two-level system (TLS) coupled to a structured environment and demonstrate that quantum synchronization can be enhanced by the classical driving field. We use the Husimi $Q$-function to characterize the phase preference and find the in-phase and anti-phase locking phenomenon in the phase diagram. Remarkably, we show that the in-phase classical driving enables a TLS to reach stable anti-phase locking in the Markovian regime. However, we find that the synergistic action of classical driving and non-Markovian effects significantly enhances the initial in-phase locking. By introducing the $S$-function and its maximal value to quantify the strength of synchronization and sketch the synchronization regions, we observe the typical signatures of the hollowed Arnold tongue in the parameter regions of synchronization. In the hollowed Arnold tongue, the synchronization regions exist both inside and outside the tongue while unsynchronized regions only lie on the boundary line. We also provide an intuitive interpretation of the above results by using the quasimode theory.

quant-ph↗

arXiv2023

Improving the precision of multiparameter estimation in the teleportation of qutrit under amplitude damping noise

Since the initial discovery of quantum teleportation, it is devoted to transferring unknown quantum states from one party to another distant partner. However, in the scenarios of remote sensing, what people truly care about is the information carried by certain parameters. The problem of multiparameter estimation in the framework of qutrit teleportation under amplitude damping (AD) noise is studied. Particularly, two schemes are proposed to battle against AD noise and enhance the precision of multiparameter estimation by utilizing weak measurement (WM) and environment-assisted measurement (EAM). For two-phase parameters encoded in a qutrit state, the analytical formulas of the quantum Fisher information matrix (QFIM) can be obtained. The results prove that the scheme of EAM outperforms the WM one in the improvements of both independent and simultaneous estimation precision. Remarkably, the EAM scheme can completely ensure the estimation precision against the contamination by AD noise. The reason should be attributed to the fact that EAM is carried out after the AD noise. Thus, it extracts information from both the system and the environment. The findings show that the techniques of WM and EAM are helpful for remote quantum sensing and can be generalized to other qutrit-based quantum information tasks under AD decoherence.

quant-ph↗

arXiv2020

Switchable Atomically Thin 2D Electrides from First-principles Prediction

Electrides, with excess anionic electrons confined in their empty space, are promising for uses in catalysis, nonlinear optics and spin-electronics. However, the application of electrides is limited by their high chemical reactivity with the environmental agents. In this work, we report the discovery of a group of two-dimensional (2D) moonolayer electrides with the presence of switchable nearly free electron (NFE) states in their electronic structures. Unlike conventional electrides, which are metals with floating electrons forming the partially occupied bands close to the Fermi level, the switchable electrides are chemically much less active semiconductors holding the NFE states that are 0.3-1.5 eV above the Fermi level. According to a high throughput search, we identified 12 2D candidates that possess such low-energy NFE states. Among them, 11 2D materials can likely be exfoliated from the known layered materials. Under external forces, such as a compressive strain, these NFE states stemming from the surface image potential will be pushed downward to cross the Fermi level. Remarkably, the critical semiconductor-metal transition can be achieved by a strain as low as 3% in 2D monolayer Na$_2$Pd$_3$O$_4$. As such, the switchable 2D electrides may provide an ideal platform for exploring novel quantum phenomena and modern electronic device applications.

cond-mat.mtrl-sci↗

arXiv2018

The Non-Quenching of $g_A$ in Nuclei and Emergent Scale Symmetry in Dense Baryonic Matter

How the axial coupling constant $g_A$ in nuclear Gamow-Teller transitions described in shell model gets "quenched" to a universal constant close to 1 can be explained by nuclear correlations in Fermi-liquid fixed point theory using a scale-symmetric chiral Lagrangian supplemented with hidden local symmetric vector mesons. Contrary to what one might naively suspect -- and has been discussed in some circles, there is no fundamental quenching at nuclear matter density due to QCD condensates. When the density of many-body systems treated with the same Lagrangian increases beyond the density $n=n_{1/2}\gsim 2n_0$ (where $n_0$ is the normal nuclear matter density) at which skyrmions representing baryons fractionize to half-skyrmions, with the $ρ$ meson driven toward the vector manifestation fixed point and a scalar meson $σ$ driven to the dilaton-limit fixed point with the nucleons parity-doubled, the dense matter supports the "pseudo-conformal" sound velocity for $n\gsim n_{1/2}$ while the trace of the energy momentum tensor remains non-vanishing. A plausible interpretation is that this signals the emergence of scale symmetry not explicitly present or hidden in QCD in the vacuum. The fundamental constant $g_A$, unaffected by QCD condensates for $n< n_{1/2}$, does go to 1 as the dilaton-limit fixed point is approached before arriving at chiral restoration, but it is not directly related to the "quenched $g_A$" in nuclei which can be explained as a Fermi-liquid fixed point quantity. The mechanism that produces a precocious pseudo-conformal sound velocity is expected to impact on the tidal deformability $Λ$ in gravity waves from coalescing neutron stars.

nucl-th↗

arXiv2018

First-principles investigation of Sc-III/IV under High Pressure

Using ab initio evolutionary structure prediction method in conjunction with density functional theory, we performed a systematic investigation on the structural transition of elemental scandium under pressure up to 250 GPa. Our prediction successfully reproduced several allotropes which have been reported in the previous literature, including the Sc-I, Sc-II and Sc-V. Moreover, we observed a series of energetically degenerate and geometrically similar structures at 110-195 GPa, which are likely to explain the unsolved phases III and IV reported by Akahama [Phys. Rev. Lett.,94, 19, 195503, (2005)]. A detailed comparison on powder X-ray diffraction pattern (PXRD) suggested that the Ccca-20 phase may account for the observed Sc-III, while Sc-IV is likely to be explained by a mixture of multiple energetically competing structures. We also used the candidate Sc-III structure as the model system to explore its superconducting behavior under pressures between 80-130 GPa. The predicted superconducting transition temperature Tc values are in satisfactory agreement with previous experimental results.

cond-mat.mtrl-sci↗

arXiv2018

Scale-Chiral Effective Field Theory for Nuclear Interactions in the Veneziano Limit

Following Golterman and Shamir, we develop scale-chiral perturbation theory in the large $N_c$ and large $N_f$ Veneziano limit that incorporates both light-quark baryons and hidden local symmetric bosons and derive a leading-order scale symmetry Lagrangian applicable in nuclear physics. Some applications in the medium-free space and baryonic matter are discussed.

nucl-th↗

arXiv2017

Nuclear Axial Currents from Scale-Chiral Effective Field Theory

By incorporating hidden scale symmetry and hidden local symmetry in nuclear effective field theory, combined with double soft-pion theorem, we predict that the Gamow-Teller operator coming from the space component of the axial current should remain unaffected by the QCD vacuum change caused by baryonic density whereas the first forbidden beta transition operator coming from the time component should be strongly enhanced. While the latter has been confirmed since some time, the former is given a support by a powerful recent {\it ab initio} quantum Monte Carlo calculation in light nuclei, also confirming the old "chiral filter hypothesis." Formulated in terms of Fermi-liquid fixed point structure of strong-coupled nuclear interactions, we offer an extremely simple resolution to the long-standing puzzle of "quenched $g_A$", $g_A^{\rm eff}\approx 1$~\cite{quenched}, in nuclear Gamow-Teller beta transitions, giant Gamow-Teller resonances and double beta decays.

nucl-th↗

arXiv2017

Derivation of Brown-Rho scaling from scale-chiral perturbation theory

The medium modified hadron properties are studied by using the scale-chiral perturbation theory $χ$PT$_σ$ in which the lightest scalar meson $f_0(500)$ is included as an explicit degree of freedom by regarding it as the Nambu-Goldstone boson of scale symmetry both spontaneously broken and explicitly broken by the QCD trace anomaly. We derive Brown-Rho scaling at the leading order of scale symmetry from $χ$PT$_σ$ and formulate how to make higher-order scale-chiral corrections going beyond the leading order of scale symmetry. By taking into account the intrinsic density dependence given by the dilaton condensate in the "bare" parameters of the Lagrangian, the medium modified hadron properties are investigated. Relying on available experimental information and certain reasonable assumptions, we arrive at the leading order scale symmetric effective theory that can be confronted with nature .

hep-ph↗

arXiv2017

Retrieving the lost fermionic entanglement by partial measurement in noninertial frames

The initial entanglement shared between inertial and accelerated observers degrades due to the influence of the Unruh effect. Here, we show that the Unruh effect can be completely eliminated by the technique of partial measurement. The lost entanglement could be entirely retrieved or even amplified, which is dependent on whether the optimal strength of reversed measurement is \emph{state-independent} or \emph{state-dependent}. Our work provides a novel and unexpected method to recover the lost entanglement under Unruh decoherence and exhibits the ability of partial measurement as an important technique in relativistic quantum information.

quant-ph↗