Period halving of Persistent Currents in Mesoscopic Mobius ladders

We investigate the period halving of persistent currents(PCs) of non-interacting electrons in isolated mesoscopic M\"{o}bius ladders without disorder, pierced by Aharonov-Bhom flux. The mechanisms of the period halving effect depend on the parity of the number of electrons as well as on the interchain hopping. Although the data of PCs in mesoscopic systems are sample-specific, some simple rules are found in the canonical ensemble average, such as all the odd harmonics of the PCs disappear, and the signals of even harmonics are non-negative. {PACS number(s): 73.23.Ra, 73.23.-b, 68.65.-k}Comment: 6 Pages with 3 EPS figure

Heralded Entanglement between Atomic Ensembles: Preparation, Decoherence, and Scaling

Heralded entanglement between collective excitations in two atomic ensembles is probabilistically generated, stored, and converted to single photon fields. By way of the concurrence, quantitative characterizations are reported for the scaling behavior of entanglement with excitation probability and for the temporal dynamics of various correlations resulting in the decay of entanglement. A lower bound of the concurrence for the collective atomic state of 0.9\pm 0.3 is inferred. The decay of entanglement as a function of storage time is also observed, and related to the local dynamics.Comment: 4 page

Probing the Melting of a Two-dimensional Quantum Wigner Crystal via its Screening Efficiency

One of the most fundamental and yet elusive collective phases of an interacting electron system is the quantum Wigner crystal (WC), an ordered array of electrons expected to form when the electrons' Coulomb repulsion energy eclipses their kinetic (Fermi) energy. In low-disorder, two-dimensional (2D) electron systems, the quantum WC is known to be favored at very low temperatures ($T$) and small Landau level filling factors ($\nu$), near the termination of the fractional quantum Hall states. This WC phase exhibits an insulating behavior, reflecting its pinning by the small but finite disorder potential. An experimental determination of a $T$ vs $\nu$ phase diagram for the melting of the WC, however, has proved to be challenging. Here we use capacitance measurements to probe the 2D WC through its effective screening as a function of $T$ and $\nu$. We find that, as expected, the screening efficiency of the pinned WC is very poor at very low $T$ and improves at higher $T$ once the WC melts. Surprisingly, however, rather than monotonically changing with increasing $T$, the screening efficiency shows a well-defined maximum at a $T$ which is close to the previously-reported melting temperature of the WC. Our experimental results suggest a new method to map out a $T$ vs $\nu$ phase diagram of the magnetic-field-induced WC precisely.Comment: The formal version is published on Phys. Rev. Lett. 122, 116601 (2019

Olig2/Plp-positive progenitor cells give rise to Bergmann glia in the cerebellum.

NG2 (nerve/glial antigen2)-expressing cells represent the largest population of postnatal progenitors in the central nervous system and have been classified as oligodendroglial progenitor cells, but the fate and function of these cells remain incompletely characterized. Previous studies have focused on characterizing these progenitors in the postnatal and adult subventricular zone and on analyzing the cellular and physiological properties of these cells in white and gray matter regions in the forebrain. In the present study, we examine the types of neural progeny generated by NG2 progenitors in the cerebellum by employing genetic fate mapping techniques using inducible Cre-Lox systems in vivo with two different mouse lines, the Plp-Cre-ER(T2)/Rosa26-EYFP and Olig2-Cre-ER(T2)/Rosa26-EYFP double-transgenic mice. Our data indicate that Olig2/Plp-positive NG2 cells display multipotential properties, primarily give rise to oligodendroglia but, surprisingly, also generate Bergmann glia, which are specialized glial cells in the cerebellum. The NG2+ cells also give rise to astrocytes, but not neurons. In addition, we show that glutamate signaling is involved in distinct NG2+ cell-fate/differentiation pathways and plays a role in the normal development of Bergmann glia. We also show an increase of cerebellar oligodendroglial lineage cells in response to hypoxic-ischemic injury, but the ability of NG2+ cells to give rise to Bergmann glia and astrocytes remains unchanged. Overall, our study reveals a novel Bergmann glia fate of Olig2/Plp-positive NG2 progenitors, demonstrates the differentiation of these progenitors into various functional glial cell types, and provides significant insights into the fate and function of Olig2/Plp-positive progenitor cells in health and disease

Interaction-induced Interlayer Charge Transfer in the Extreme Quantum Limit

An interacting bilayer electron system provides an extended platform to study electron-electron interaction beyond single layers. We report here experiments demonstrating that the layer densities of an asymmetric bilayer electron system oscillate as a function of perpendicular magnetic field that quantizes the energy levels. At intermediate fields, this interlayer charge transfer can be well explained by the alignment of the Landau levels in the two layers. At the highest fields where both layers reach the extreme quantum limit, however, there is an anomalous, enhanced charge transfer to the majority layer. Surprisingly, when the minority layer becomes extremely dilute, this charge transfer slows down as the electrons in the minority layer condense into a Wigner crystal. Furthermore, by examining the quantum capacitance of the dilute layer at high fields, the screening induced by the composite fermions in an adjacent layer is unveiled. The results highlight the influence of strong interaction in interlayer charge transfer in the regime of very high fields and low Landau level filling factors.Comment: Please see the formal version on PR

High-Fidelity Archeointensity Results for the Late Neolithic Period From Central China

Archeomagnetism focuses on exploring high-resolution variations of the geomagnetic field over hundreds to thousands of years. In this study, we carried out a comprehensive study of chronology, absolute and relative paleointensity on a late Neolithic site in central China. Ages of the samples are constrained to be ~3,500–3,000 BCE, a period when available paleointensity data are sparse. We present a total of 64 high-fidelity absolute paleointensities, demonstrating the field varied quickly from ~55 to ~90 ZAm2 between ~3,500–3,000 BCE. Our results record a new archeomagnetic jerk around 3,300 BCE, which is probably non-dipolar origin. The new results provide robust constraints on global geomagnetic models. We calculated a revised Chinese archeointensity reference curve for future application. The variations of absolute and relative paleointensity versus depth show good consistency, reinforcing the reliability of our results. This new attempt of combining absolute and relative paleointenstiy provides a useful tool for future archeomagnetic research