Highlights
SPECIAL TOPIC——Quantum transport in topological materials and devices
COVER ARTICLE
2025, 74 (7): 077401.
doi: 10.7498/aps.74.20241672
Abstract +
The hybrid system of low-dimensional electronic materials and superconducting materials has always been an attractive structure for studying mesoscopic transport and low-dimensional superconducting properties. Low-dimensional structures with strong spin-orbit coupling exhibit rich quantum phenomena combined with superconducting macroscopic quantum states. Therefore it has become an important platform for exploring novel physical properties and developing new topological quantum devices. The construction of hybrid superconducting devices based on high-quality one-dimensional electronic materials and the exploration of interfacial quantum transport phenomena have become the research frontiers. It is crucial to understand the characteristic scattering mechanisms and quantum transport processes in these hybrid systems on a nanoscale. The study of the coupling mechanism between the charge state and the topological localized state, and the experimental probe of the intrinsic transport properties of the topological states are the key issues, which enable the development of the new principles and methods for novel superconducting nano electronic devices and topological quantum devices. Due to the competition of multiple energy scales and complex bound states in these hybrid structures, the device physics and measurement schemes are facing unprecedented challenges. This paper reviews recent research progress of hybrid superconducting devices based on one-dimensional electronic systems, focusing on the material systems based on semiconducting nanowires and carbon nanotubes. Semiconducting nanowires with strong spin-orbit coupling and large Landau g-factor are expected to support Majorana bound states, and further improvements are needed in the material quality, interface between superconductors and nanowires, understanding of the transport mechanism, and detection scheme. The construction strategies of extending topological phase space, including broken symmetry, helical modes, semiconducting characteristics, and attenuation of the external magnetic field, are proposed and discussed in hybrid superconducting devices based on carbon nanotubes. The main phenomena and experimental challenges, ranging from material to device physics, are introduced briefly. Finally, this paper summarizes and prospects the development and transport studies of topological quantum devices based on one-dimensional systems.
Abstract +
High-temperature superconductivity, a fundamental topic in condensed matter physics, presents one of the critical scientific challenges of this century. The potential for breakthroughs in this field not only promises to reveal numerous novel quantum phenomena and deepen our understanding of quantum many-body physics but also to significantly drive advancements in experimental techniques, theories, and methodologies in probing correlated quantum systems. More importantly, as a non-perturbative quantum system, high-temperature superconductivity offers an ideal platform and a crucial driving force for systematically establishing non-perturbative quantum field theory. Currently, research on high-temperature superconductivity stands at a critical turning point. Achieving significant breakthroughs requires the development of cutting-edge detection technologies built upon novel concepts, the establishment of innovative theoretical frameworks and methodologies, and insightful elucidation of the physical pictures revealed by experimental findings. Such extensive exploration is vital for unveiling fundamental relationships and identifying the governing principles. By integrating these efforts, we can gain profound insights into the mechanisms of high-temperature superconductivity and significantly expand the horizons of quantum many-body theory.
SPECIAL TOPIC—Technology of magnetic resonance
EDITOR'S SUGGESTION
2025, 74 (7): 078701.
doi: 10.7498/aps.74.20241759
Abstract +
SPECIAL TOPIC—Technology of magnetic resonance
EDITOR'S SUGGESTION
2025, 74 (7): 077402.
doi: 10.7498/aps.74.20241709
Abstract +
Solid-state nuclear magnetic resonance (NMR) has emerged as an important technique for material characterization, finding extensive applications across a diverse range of disciplines including physics, materials science, chemistry, and biology. Its utility stems from the ability to probe the local atomic environments and molecular dynamics within solid materials, which provides information on the composition of the material. In recent years, the scope of solid-state NMR has expanded into the realm of quantum information science and technology, where its abundant many-body interactions pulse control methodologies make it have significant research value and application potential. This paper offers a comprehensive overview of the research objects and theoretical underpinnings of solid-state NMR, delving into the critical nuclear spin interaction mechanisms and their corresponding Hamiltonian forms. These interactions, which include dipolar coupling, chemical shift anisotropy, and quadrupolar interactions, are fundamental to the interpretation of NMR spectra and the understanding of material properties at the atomic level. Moreover, the paper introduces typical dynamical control methods employed in the manipulation of solid-state nuclear spins. Techniques such as dynamical decoupling, which mitigates the effects of spin-spin interactions to extend coherence times, and magic-angle spinning, which averages out anisotropic interactions to yield high-resolution spectra. These methods are essential for enhancing the sensitivity and resolution of NMR experiments, enabling the extraction of detailed structural and dynamic information from complex materials. Then we introduce some recent advancements in quantum control based on solid-state NMR, such as nuclear spin polarization enhancement techniques, which include dynamic nuclear polarization (DNP) and cross polarization (CP), significantly boost the sensitivity of NMR measurements. Additionally, the control techniques of Floquet average Hamiltonians are mentioned, showcasing their role in the precise manipulation of quantum states and the realization of quantum dynamics. Finally, the paper presents a series of seminal research works that illustrate the application of solid-state NMR quantum control technologies in the field of quantum simulation. These studies demonstrate how solid-state NMR can be leveraged to simulate and investigate quantum many-body systems, providing valuable insights into quantum phase transitions, entanglement dynamics, and other phenomena relevant to quantum information science. By bridging the gap between fundamental research and practical applications, solid-state NMR continues to play a crucial role in advancing our understanding of quantum materials and technologies.
SPECIAL TOPIC—Quantum information processing
EDITOR'S SUGGESTION
2025, 74 (7): 070301.
doi: 10.7498/aps.74.20250029
Abstract +
Studying the quantum resources of neutrino oscillations is a topic worth exploring. This review mainly introduces the use of quantum resource theory to characterize the quantum resource characteristics of three-flavor neutrino oscillations, and the specific evolutionary patterns of different entanglement measures in three-flavor neutrino oscillations. In addition, by comparing the cases of different entanglement evolutions, the optimal method of quantifying entanglement in three-flavor neutrino oscillations can be obtained. Moreover, this review also focuses on the quantifying the quantumness of neutrino oscillation observed experimentally by using the l1-norm of coherence. The maximal coherence is observed in the neutrino source from the KamLAND reactor. Furthermore, we examine the violation of the Mermin inequality and Svetlichny inequality to study the nonlocality in three-flavor neutrino oscillations. It is shown that even though the genuine tripartite nonlocal correlation is usually existent, it can disappear within specific time regions. In addition, this review also presents the trade-off relations in the quantum resource theory of three-flavor neutrino oscillations, mainly based on monogamy relations and complete complementarity relations. It is hoped that this review can bring inspiration to the development of this field.
SPECIAL TOPIC—Quantum transport in topological materials and devices
EDITOR'S SUGGESTION
2025, 74 (7): 076401.
doi: 10.7498/aps.74.20250122
Abstract +
With the development of the topological theory, it is believed that topological states originate from topologically protected interfaces in condensed matter systems. Significantly, by adjusting the topological interfaces, one can manipulate the transport properties of a sample, thereby possessing distinct features. This paper briefly reviews recent progresses about topological interfaces and their potential applications in quantum devices. In the first part, we expound the fundamental ideas about topological interfaces in disordered Chern insulators. Based on their transport properties, the designs of programmable circuits and logical gates are also clarified. These designs significantly improve the utilization of sample compared with topological surface devices. The second part focuses on the topological interfaces in three-dimensional systems, which exhibits the layertronics of the interfaces. We present axion insulator MnBi2Te4 as a typical example, and the realization of the basic layertronics devices is proposed. Finally, this work summarizes the advantages of topological interface devices and proposes some potential breakthroughs to be achieved in this field.
INSTRUMENTATION AND MEASUREMENT
EDITOR'S SUGGESTION
2025, 74 (7): 074203.
doi: 10.7498/aps.74.20241652
Abstract +
Distributed optical fiber temperature measurement system is widely used in the fields of substation, power cable, natural gas transmission pipeline and other temperature measurement systems. It can continuously measure the temperature information at each location along the sensing direction. Raman distributed optical fiber temperature measurement system demodulates the temperature information based on Raman Stokes scattered light and anti-Stokes scattered light power, and the Raman scattering light power directly affects the temperature measurement accuracy. So, it is a challenging task to control the hardware of the system to ensure the feasiblity of the Raman sacttering signals. The laser pulse power, and the gain of avalanche photodetector may vary randomly in the system, resulting in fluctuations in the acquired Raman scattered light power data. Therefore, a scheme of Raman distributed fiber temperature measurement system based on dynamic calibration is proposed in this work, and by setting up the temperature calibration unit and combining the proposed power correction algorithm and previous calibration data, the Raman Stokes scattering light and Raman anti-Stokes scattering light power are calibrated at the same laser pulse power level and avalanche photodetector gain, thereby improving the temperature measurement accuracy of the system. For the performance demonstration of the new scheme, the experimental system adopts 50-ns laser pulse to carry out temperature measurement experiments with a 4.6-km long single-mode fiber. The results show that in the temperature measurement range from 35 ℃ to 95 ℃, based on the traditional temperature demodulation algorithm, the temperature deviation measured is in the range from –5.8 ℃ to 1.0 ℃, and the root mean square error is 4.0 ℃, and by the dynamic calibration algorithm, the deviation of deviation measured is within –0.8 ℃ to 0.9 ℃ and the root mean square error is 0.5 ℃. Therefore, the novel Raman-type distributed optical fiber temperature measurement system proposed in this work has the function to dynamically correct the Raman-type scattered light power to suppress the influence caused by instability of the key devices such as pulsed laser and avalanche photodetector and improve the temperature measurement accuracy, which is valuable in practical engineering applications.
INSTRUMENTATION AND MEASUREMENT
EDITOR'S SUGGESTION
2025, 74 (7): 070302.
doi: 10.7498/aps.74.20241621
Abstract +
High-precision gravity field mapping plays a critical role in geological survey, resource exploration, and geoid modeling. The traditional ground-based static absolute gravity measurements possess high accuracy, but they are fundamentally constrained by low operational efficiency and inability to survey complex terrains such as river networks, lakes, and mountainous regions. This study tries to address these limitations through the development of an airborne absolute gravity measurement system based on quantum gravimeters. At a flight altitude of 1022 m and a speed of 240 km/h of the airplane, after a filtering process of 3 km, the measured gravity value shows a standard deviation of approximately 8.86 mGal. Furthermore, a comparative analysis with the EGM2008 gravity model shows a residual standard deviation of 8.16 mGal, validating the consistency of the system with established geophysical references. The experimental results confirm the operational feasibility of quantum gravimeters in scenarios of airborne dynamic measurement, demonstrating the viability of this technological framework for high-resolution gravity field mapping.
EDITOR'S SUGGESTION
2025, 74 (7): 074101.
doi: 10.7498/aps.74.20241677
Abstract +
EDITOR'S SUGGESTION
2025, 74 (7): 074301.
doi: 10.7498/aps.74.20241747
Abstract +
As an important and promising experimental method of simulating the containerless state in outer space, acoustic levitation provides excellent contact-free condition for investigating solidification process. Meanwhile, the radiation pressure and acoustic streaming caused by nonlinear effects bring various kinds of novel phenomena to crystallization kinetics. In this work, high-speed charge coupled device (CCD), low-speed camera and infrared thermal imager are used simultaneously to observe the crystallization process of acoustically levitated SCN-DC transparent alloys. The undercooling ability and solidification process of alloy droplets with different aspect ratios are explored in acoustic levitation state. For hypoeutectic SCN-10%DC, eutectic SCN-23.6%DC and hypereutectic SCN-40%DC alloys, the experimental maximum undercoolings reach 22.5 K (0.07TL), 16 K (0.05TE) and 32.5 K (0.1TL) and the corresponding crystal growth velocities are 27.91, 0.21 and 0.45 mm/s, respectively. In SCN-10%DC hypoeutectic alloy, the nucleation mode of SCN dendrite changes from edge nucleation into random nucleation with the increase of undercooling. For SCN-23.6%DC eutectic alloy, when the undercooling exceeds 12.6 K, DC dendrites preferentially nucleate and grow, and then the (SCN+DC) eutectic adheres to and grows on DC dendrites. Moreover, the growth interface of DC dendrites gradually changes from sharp into smooth within SCN-40%DC hypereutectic alloy as the undercooling degree rises. The undercooling distribution curve and nucleation probability variation trend versus aspect ratio are analyzed. It is found that as the aspect ratio increases, undercooling of alloy droplet first increases, then decreases, and finally remains almost unchanged. Further analysis shows that with the increase of aspect ratio, the cooling rate will rise and thus enhance the undercooling. However, the increase in surface nucleation rate and the droplet oscillation inhibits deep undercooling of alloy droplet. Therefore, the coupled effects of cooling rate, surface nucleation rate, and droplet oscillation determine the undercooling of the alloy. In the case of SCN-40% DC hypereutectic alloy, the acoustic streaming and surface oscillation arising from acoustic field are the main factors intensifying surface nucleation.
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