AAPPS Bulletin最新文献

This article highlights the significance of level lifetime measurements in nuclear structure studies that principally center on probing the myriad excitation phenomena exhibited by nuclei through evolving regimes of excitations in energy, angular momentum, and isospin. The same has been illustrated through discussions on some of the measurements undertaken using the Indian National Gamma Array (INGA) set up at the BARC-TIFR Pelletron LINAC Facility (PLF) in TIFR, Mumbai. The diverse physics that could be addressed in such endeavors provides the impetus to work towards developing better facilities for spectroscopic pursuits.

Comprehensive neutron diagnostics have been developed and used to study magnetic confinement fusion plasmas. The neutron emission spectrometer is one of the most powerful tools for understanding fusion plasma physics. Neutron spectroscopy was originally developed to measure the fuel ion temperature in thermal plasmas. With the advent of fast ion heating, the role of neutron spectroscopy has evolved to deepen the understanding of fast ion confinement. Since neutrons are primarily produced by the fusion reaction between the bulk ion and the fast ion, the neutron energy carries information about the fast ion energy. The details of neutron emission spectrometers, i.e., time-of-flight spectrometer, magnetic proton recoil spectrometer, and compact neutron emission spectrometer, as well as representative results of neutron spectrometry in Large Helical Device are reviewed.

To satisfy the needs of modern intelligent society for power supplies with long-endurance ability, Li-rich Mn-based layered oxides (LRMOs) are receiving much attention because of their ultrahigh capacity. However, their real-world implementation is hindered by the serious voltage decay, which results in a continuous decrease in energy density. The understanding on voltage decay still remains a mystery due to the complicated hybrid cationic-anionic redox and the serious surface-interface reactions in LRMOs. Moreover, some of the mechanisms are occasionally contradictory, indicating that the origin of voltage decay is still unclear. As a result, none of the innovative strategies proposed on the basis of mechanisms has effectively alleviated the problem of voltage decay, and voltage decay becomes a long-term distress of LRMOs. Therefore, it is particularly crucial to sort out the mutual relation of various mechanisms, which helps to go back to the source of voltage decay. In this review, we summarize the current mechanisms of voltage decay as structural evolution and oxygen chemistry, and attempt to trace the origin of voltage decay for LRMOs. In addition, we discuss how current researches address the issue with generalized guidance in designing appropriate strategies based on mechanisms.

Quantum clock synchronization (QCS) can measure out the high-precision clock difference among distant users, which breaks through the standard quantum limit by employing the properties of quantum entanglement. Currently, the wavelength division multiplexed QCS network has been demonstrated with a spontaneous parametric down-conversion entangled photon source. In this paper, we propose a more efficient QCS network scheme with the wavelength multicasting entangled photon source, which can decrease at least 25% of wavelength channel consumption under the identical network scale. Afterwards, a four node QCS network is demonstrated, where the wavelength multicasting entangled photon source is utilized with dual-pumped four-wave mixing silicon chip. The experimental results show that the measured time deviation is 3.4 ps with an average time of 640 s via the multiple fiber links of more than 10 km.

We present a theoretical review of the recent progress in non-equilibrium BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover physics. As a paradigmatic example, we consider a strongly interacting driven-dissipative two-component Fermi gas where the non-equilibrium steady state is tuned by adjusting the chemical potential difference between two reservoirs that are coupled with the system. As a powerful theoretical tool to deal with this system, we employ the Schwinger-Keldysh Green’s function technique. We systematically evaluate the superfluid transition, as well as the single-particle properties, in the non-equilibrium BCS-BEC crossover region, by adjusting the chemical potential difference between the reservoirs and the strength of an s-wave pairing interaction associated with a Feshbach resonance. In the weak-coupling BCS side, the chemical potential difference is shown to imprint a two-step structure on the particle momentum distribution, leading to an anomalous enhancement of pseudogap, as well as the emergence of exotic Fulde-Ferrell-Larkin-Ovchinnikov-type superfluid instability. Since various non-equilibrium situations have recently been realized in ultracold Fermi gases, the theoretical understanding of non-equilibrium BCS-BEC crossover physics would become increasingly important in this research field.

Polaron, a typical quasi-particle that describes a single impurity dressed with surrounding environment, serves as an ideal platform for bridging few- and many-body physics. In particular, different few-body correlations can compete with each other and lead to many intriguing phenomena. In this work, we review the recent progresses made in understanding few-body correlation effects in attractive Fermi polarons of ultracold gases. By adopting a unified variational ansatz that incorporates different few-body correlations in a single framework, we will discuss their competing effects in Fermi polarons when the impurity and majority fermions have the same or different masses. For the equal-mass case, we review the nature of polaron-molecule transition that is driven by two-body correlations, and especially highlight the finite momentum character and huge degeneracy of molecule states. For the mass-imbalanced case, we focus on the smooth crossover between polaron and various dressed clusters that originate from high-order correlations. These competing few-body correlations reviewed in Fermi polarons suggest a variety of exotic new phases in the corresponding many-body system of Fermi-Fermi mixtures.