Highlights
SPECIAL TOPIC—2D materials and future information devices·COVER ARTICLE
COVER ARTICLE
2025, 74 (17): 178501.
doi: 10.7498/aps.74.20250648
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Two-dimensional (2D) semiconductor materials exhibit tremendous potential for post-Moore integrated circuits due to their unique physical properties and superior electrical characteristics. However, critical challenges in polarity modulation and complementary integration have significantly hindered the practical applications of 2D materials. The development of compatible polarity-modulation techniques has emerged as a critical step in achieving device functional integration for constructing 2D materials-based complementary circuits. This study innovatively proposes a one-step-annealing-driven polarity-modulation strategy for 2D semiconductors. It is demonstrated in this study that the conduction behavior of Pd-contacted WSe2 transistors transitions from n-type to p-type dominance after annealing, while Cr-contacted devices maintain n-type dominance. Based on this polarity-modulation strategy, by selectively fabricating source and drain electrodes with different metal materials (Pd and Cr) on the same WSe2, combined with a one-step annealing process, the monolithic integration of complementary transistors is achieved, thereby realizing inverter function through device interconnection. The fabricated inverters exhibit a high voltage gain of 23 and a total noise margin of 2.3 V(0.92 Vdd) at an applied Vdd of 2.5 V. This work not only establishes a novel technical pathway for polarity modulation in 2D materials but also provides crucial technological support for developing 2D semiconductor-based complementary logic circuits.
SPECIAL TOPIC—Order tuning in disordered alloys·COVER ARTICLE
COVER ARTICLE
2025, 74 (16): 166101.
doi: 10.7498/aps.74.20250563
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The engineering applications of amorphous alloys are largely restricted by structural relaxation. Notably, the dissipative component of cyclic loading dominates the thermodynamic energy in practical applications of amorphous alloys. Mechanical rejuvenation, achieved through cyclic loading, offers an effective solution to this problem. In this study, we systematically investigate the deformation characteristics and rejuvenation mechanism of Pd20Pt20Cu20Ni20P20 amorphous alloy under mechanical cycling using dynamic mechanical analysis (DMA). By employing a two-phase Kelvin model and continuous relaxation time spectrum, we elucidate the interplay between mechanical deformation and energy dissipation during cyclic loading. The experimental results demonstrate that the strain rate increases significantly with the intensity of mechanical cycling, indicating enhanced dynamic activity in the glassy matrix. At higher cycling intensities, anelastic deformation is promoted, activating a broader spectrum of defects and amplifying dynamic heterogeneity. Through differential scanning calorimetry (DSC), we establish a quantitative correlation between deformation and energetic state, revealing that rejuvenation originates from internal heating induced by anelastic strain. A comparative analysis with creep deformation reveals that mechanical cycling exhibits a superior rejuvenation potential, attributed to its ability to periodically excite multi-scale defect clusters and sustain non-equilibrium states. The key findings of this work include: 1) Deformation mechanism: Cyclic loading enhances atomic mobility and facilitates deformation unit activation; 2) Energy landscape: The enthalpy change (ΔH) measured by DSC provides a direct metric for rejuvenation efficiency; 3) Dynamic heterogeneity: Mechanical cycling broadens the relaxation time spectrum, reflecting increased dynamic heterogeneity.
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This paper conducts numerical studies on superradiance and Hawking radiation of a specific rotating acoustic black hole model characterized by parameters A and B, within the framework of analogue gravity. The standard radial wave equation for scalar perturbations in the effective metric of this model is solved numerically by using an adaptive Runge-Kutta method with tortoise coordinates; this approach necessitates careful numerical inversion of the coordinate transformation near the horizon via a root-finding algorithm. By imposing appropriate boundary conditions, we extract the reflection coefficient $\mathcal{R}$ and transmission coefficient $\mathcal{T}$ in a range of frequencies ω. Our results clearly demonstrate superradiance, with the reflectivity $|\mathcal{R}|^2$ exceeding unity for $\omega < m\varOmega_{\rm{H}} = 1$ (where $m=-1$ and $\varOmega_{\rm{H}}=-1$), which confirms energy extraction from the rotating background. The high accuracy of our method is validated by the flux conservation relation, $|\mathcal{R}|^2 + $$ [(\omega - m\varOmega_{\rm{H}})/\omega]|\mathcal{T}|^2 = 1$, which typically has a numerical precision of $ 10^{-8}$. Furthermore, using the derived Hawking temperature and the rotation modified Bose-Einstein distribution, we calculate the Hawking radiation power spectrum $P_\omega$, and use the numerically obtained transmission coefficient $|\mathcal{T}|^2$ as the greybody factor of the model. A prominent feature of $P_\omega$ is its sharp enhancement (or divergence) as ω approaches the threshold $m\varOmega_{\rm{H}}$ from above, which is a characteristic directly related to the denominator of the Bose-Einstein factor. This research also reveals that superradiant amplification and Hawking spectrum characteristics are significantly dependent on the specific values of flow parameters A and B, even when the superradiant threshold $m\Omega_H$ is kept unchanged. This detailed numerical study provides quantitative results for the scattering and radiation properties of this model, and also for strong support for the analogue gravity framework.
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Topologically protected waveguides have aroused increasing interest due to their robustness against disorder and defects. In parallel, the advent of non-Hermitian physics with its inherent gain-and-loss mechanisms has introduced new tools for manipulating wave localization and transport. However, most attempts to combine non-Hermitian effects with topological systems uniformly impose the non-Hermitian skin effect (NHSE) on all modes, without selectivity targeting topological states. In this work, we propose a scheme thatachieves topologically selective NHSE by combining sub-symmetry-protected boundary modes with long-range non-reciprocal couplings. In an improved Su–Schrieffer–Heeger (SSH) chain, we analytically demonstrate that robust zero-energy edge modes can be preserved even in spectra filled with bulk states, while selectively applying the NHSE to the trivial bulk states to achieve the spatial separation between topological state and bulk state. By adjusting the long-range couplings a non-Hermitian phase transition can be observed in the complex energy spectrum: it transitions from a closed loop (circle) to an open arc, and ultimately to a reversely coiled loop. These transitions correspond respectively to a leftward NHSE, the disappearance of the NHSE, and a rightward NHSE. According to the calculations of the generalized Brillouin zone (GBZ), we confirm this transition by observing the GBZ passing through the unit circle, indicating a change in the direction of NHSE.We further extend our model to a two-dimensional higher-order SSH lattice, where selective non-Hermitian modulation enables clear spatial separation between topological corner states and bulk modes. To quantify this, we compute the local density of states (LDOS) in the complex energy plane for site 0 (a topologically localized corner) and site 288 (a region exhibiting NHSE). The comparison of LDOS between the two sites reveals that the topological states are primarily localized at site 0, while the bulk states affected by NHSE accumulate at site 288.To validate the theoretical predictions, we perform finite-element simulations of optical resonator arrays by using whispering-gallery modes. By adjusting the coupling distances and incorporating gain/loss through refractive index engineering, we replicate the modified SSH model and confirm the selective localization of topological and bulk modes.Our results provide a robust method for selectively exciting and spatially controlling the topological states in non-Hermitian systems, and also lay a foundation for future low-crosstalk high-stability topological photonic devices.
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Channel proteins act as precise molecular regulators of transmembrane transport, which is a fundamental process essential for maintaining cellular homeostasis. These proteins dynamically modulate their functional states through conformational changes, thereby forming the structural basis for complex physiological processes such as signal transduction and energy metabolism. Single-molecule fluorescence spectroscopy and single-channel patch-clamp electrophysiology represent two cornerstone techniques in modern biophysics: the former enables molecular-resolution analysis of structural dynamics, while the latter provides direct functional characterization of ion channel activity. Despite their complementary capabilities, integrating these techniques to simultaneously monitor protein conformational dynamics and functional states remains technically challenging, primarily due to the strong autofluorescence background inherent in single-molecule imaging in cellular environments. To address this limitation, we develop a spatially selective optical excitation system capable of localized illumination. By integrating tunable optical modules, we generate a dynamically adjustable excitation field on living cell membranes, achieving precise spatial registration between the excitation volume and the patch-clamp recording site. This system achieves submicron-scale alignment between the excitation zone and the micropipette contact area, enabling simultaneous electrophysiological recording and background-suppressed fluorescence detection within the clamped membrane domain. Experimental validation demonstrates that the systemcan perform single-molecule fluorescence imaging and trajectory analysis within a specified observation areas, with imaging resolution inversely related to the size of the illuminated region. Optimized optical design allows for precise excitation targeting while minimizing background illumination, thereby achieving high signal-to-noise ratio single-molecule imaging and significantly reducing photodamage. Integration with cell-attached patch-clamp configurations establishes a dual-modality platform for synchronized acquisition of single-molecule fluorescence images and single-channel recordings. The validation using mechanosensitive mPiezo1 channels confirms the system’s compatibility with single-channel recording, indicating that optical imaging induces no detectable interference to electrophysiological signal acquisition. This method overcomes longstanding challenges in the simultaneous application of single-molecule imaging and electrophysiological techniques in live-cell environments. It establishes a novel experimental framework for investigating the structure-function relationships of channel proteins and membrane-related molecular machines through spatially coordinated optoelectronic measurements on live-cell membranes, which has broad applicability in molecular biophysics and transmembrane transport mechanism research.
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CeRh2As2, as a recently discovered Ce-based 122-type heavy-fermion superconductor, has attracted much attention due to its non-Fermi-liquid behavior and two-phase superconductivity. The tetragonal crystal structure of CeRh2As2 maintains global centrosymmetry, which makes even-parity and odd-parity superconducting states different rather than mixed. The Ce site exhibits local inversion symmetry breaking, which results in staggered Rashba spin-orbit coupling. This may lead to the c axis field-induced transition between two superconducting phases and high critical field. Given the novel physics in CeRh2As2, including a possible quantum critical point and a spin-fluctuation-mediated superconducting pairing mechanism, the ultra-low-temperature electrical and thermal transport properties of CeRh2As2 under various magnetic fields are investigated in this work. The zero-field resistivity reveals a superconducting transition at the critical temperature Tc = 0.34 K. At a magnetic field of 1 T, a minimum resistivity appears near T0$ \approx $0.42 K, which may be due to partial gap opening caused by Fermi surface nesting, indicating that the system enters into a magnetically ordered state, which is not observed in zero field. In the temperature range from T0 to 2 K, the system exhibits non-Fermi-liquid behavior $ \rho\sim{{T}}^{0.44} $, indicating proximity to a quantum critical point. The superconducting transition is fully suppressed at 7 T, with resistivity recovering Fermi-liquid behavior at low temperature. No significant anomaly is observed in the zero-field thermal conductivity of CeRh2As2 near Tc. This absence of anomaly may be attributed to the high residual resistivity of the sample, and the reduction in carrier density during the superconducting transition and the T0 phase transition. It requires optimizing single crystal growth to reduce the effects of lattice defects or chemical disorder on thermal transport. Upon applying magnetic field, the thermal conductivity curve exhibits a small upward shift relative to its zero-field curve. At 0.15 K, thermal conductivity rises with the increase of magnetic field and is saturated at higher fields (above 5 T). In the normal state at 7 T, it is found that the electrical resistivity and thermal conductivity satisfy the Wiedemann-Franz law, indicating that both charge and heat transport are governed by the same quasiparticles, which is consistent with the Fermi-liquid behavior observed in resistivity under this field.
SPECIAL TOPIC—Technology of magnetic resonance
COVER ARTICLE
2025, 74 (11): 117401.
doi: 10.7498/aps.74.20250271
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Quantum sensing utilizes the quantum resources of well-controlled quantum systems to measure small signals with high sensitivity, and has great potential in both fundamental science and concrete applications. Interacting quantum systems have attracted increasing interest in the field of precise measurements, owing to their potential to generate quantum-correlated states and exhibit rich many-body dynamics. These features provide a novel avenue for exploiting quantum resources in sensing applications. Although previous studies have shown that using such systems can improve sensitivity, they mainly focused on measuring individual physical quantities. In experiment, the challenge of using interacting quantum systems to achieve high-precision measurements of multiple physical parameters simultaneously has not been explored to a large extent. In this study, we demonstrate a first realisation of interaction-based multiparameter sensing by using strongly interacting nuclear spins under ultra-low magnetic field conditions. We find that, as the interaction strength among nuclear spins becomes significantly larger than their Larmor frequencies, a different regime emerges where the strongly interacting spins can be simultaneously sensitive to all components of a multidimensional field, such as a three-dimensional magnetic field. Moreover, we observe that the strong interactions between nuclear spins can increase their quantum coherence times to as long as several seconds, thereby improving measurement precision. Our sensor successfully achieves precision measurement of three-dimensional vector magnetic fields with a field sensitivity reaching the order of 10–11 T and an angular resolution as high as 0.2 rad. Importantly, this approach eliminates the need for external reference fields, thereby avoiding calibration errors and technical noise commonly encountered in traditional magnetometry. Experimentally optimized protocol further enhances the sensitivity of the interacting spin-based sensor by up to five orders of magnitude compared with non-interacting or classical schemes. These results demonstrate the enormous potential of interacting spin systems as a powerful platform for high-precision multi-parameter quantum sensing. The techniques developed here pave the way for a new generation of quantum sensors that use intrinsic spin interactions to exceed the traditional sensitivity limits, presenting a promising route toward ultra-sensitive, calibration-free magnetometry in complex environments.
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The eigenstate thermalization hypothesis describes the nonequilibrium dynamics of an isolated quantum many-body system, during which a pure state becomes locally indistinguishable from a thermal ensemble. The discovery of quantum many-body scars (QMBS) shows a weak violation of ergodicity, characterized by coherent oscillations of local observables after a quantum quench. These states consist of the tower of regular eigenstates which are equally spaced in the energy spectrum. Although subextensive entanglement scaling is a primary feature widely used to detect QMBS numerically as entropy outliers, rainbow scars exhibit volume-law scaling, which may challenge this property. In this work, we construct the rainbow scar state in the fracton model on a two-leg ladder. The fracton model is composed of four-body ring-exchange interactions, exhibiting global time-reversal symmetry $ \hat{{{\cal{T}}}}={{\cal{K}}} {\mathrm{i}} \hat{\sigma}^y $ and subsystem $ {\hat{U}(1)}=\displaystyle \prod\nolimits_{j \in \{\text {row/col}\}} {\mathrm{exp}}\Big({{\mathrm{i}} \dfrac{\theta}{2} \hat{\sigma}_j^z}\Big)$ symmetry. The subsystem symmetry constrains particle mobility, hindering the establishment of thermal equilibrium and leading to a series of anomalous dynamical processes. We construct the rainbow scar state with distributed four-body GHZ states whose entanglement entropy follows the volume law. By calculating the eigenstates of the fracton model with exact diagonalization, the rainbow scar state consists of a series of degenerate high-energy excited states that are not significant outliers among other eigenstates in the spectrum. By introducing the on-site interaction to break the time-reversal symmetry, the degeneracy of rainbow scar states is lifted into an equally spaced tower of states, ensuring the revival of the initial state. However, when subsystem $\hat U(1) $ symmetry is broken, the scar state is quickly thermalized, indicating that the weak thermalization may be protected by subsystem $\hat U(1) $ symmetry. Additionally, we propose a scheme for preparing the rainbow scar state by modulating the strength of the four-body interaction and $ \hat{\sigma}^z$ operations, analyzing the influence of noise on the strength of the four-body interaction. This work provides new insights into the weak thermalization processes in fracton model and aids in understanding the nature of ETH-violation in various nonequilibrium systems.
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In ion optical clock systems, the motional effect of trapped ions is a key factor determining clock performance and currently representing a key limitation in achieving lower uncertainty between different ion-based optical clocks. According to the first liquid nitrogen-cooled Ca+ ion optical clock (2022 Phys. Rev. Appl. 17 034041 ), we develop a new physical system for a second Ca+ ion optical clock and make significant improvements to its ion trapping apparatus. These improvements primarily focus on two aspects. The first aspect is that we design and implement an active stabilization system for the RF voltage, which stabilizes the induced radio-frequency (RF) signal on the compensation electrodes by adjusting the amplitude of the RF source in real time. This method effectively suppresses long-term drifts in the radial secular motion frequencies to less than 1 kHz, achieving stabilized values of $\omega_x = 2\pi \times 3.522(2)\;\mathrm{MHz}$ and $\omega_y = 2\pi \times 3.386(2)\;\mathrm{MHz}$. The induced RF signal is stabilized at 59121.43(12) µV, demonstrating the high precision of the stabilization system. The second aspect is that we optimize the application of compensation voltages by directly integrating the vertical compensation electrodes into an ion trap structure. This refinement can suppress excess micromotion in all three mutually orthogonal directions to an even lower level. Tuning the RF trapping frequency close to the magic trapping condition of the clock transition, we further evaluate the excess micromotion-induced frequency shift in the optical clock to be $2(1) \times 10^{-19}$. To quantitatively assess the secular-motion of the trapped ion, we measure the sideband spectra on the radial and axial motion modes, both red and blue sideband spectra. From these measurements, we accurately determine the mean phonon number in the three motional modes after Doppler cooling, corresponding to an average ion temperature of $0.78(39)\;\mathrm{mK}$, which is close to the Doppler cooling limit. The corresponding second-order Doppler shift is evaluated to be $-(2.71 \pm 1.36) \times 10^{-18}$. The long-term stability of the radial secular motion frequency provides favorable conditions for implementing three-dimensional sideband cooling in future experiments, which will further reduce the second-order Doppler shift. These advancements not only enhance the overall stability of the optical clock but also lay the foundation for reducing its systematic uncertainty to the $10^{-19}$ level.
SPECIAL TOPIC—Order tuning in disordered alloys
COVER ARTICLE
2025, 74 (8): 086101.
doi: 10.7498/aps.74.20250097
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