Electron transport of a quantum wire with spatially periodic spin–orbit coupling

Electron transport properties of an ideal one-dimensional (1D) quantum wire are studied including spatially periodic Rashba spin–orbit coupling (SOC) and Dresselhaus SOC. By comparing with the previous work [S.J. Gong, Z.Q. Yang, J. Phys. Condens. Matter 19 (2007) 446209], two transmission gaps appear in the transmission probability of electrons and their widths are also broadened dramatically. Moreover, it is found that their widths are sensitive not only to the strength of SOCs but also to the length ratio of SOCs segment and non-SOCs segment. In addition, a ‘circle-type’ transmission behavior has been found by tuning the strength of SOCs continuously. Our results may extend the previous work and provide an more effective method to manipulate the current in nanoelectric devices.     

Semiclassical matrix model for quantum chaotic transport with time-reversal symmetry

We show that the semiclassical approach to chaotic quantum transport in the presence of time-reversal symmetry can be described by a matrix model. In other words, we construct a matrix integral whose perturbative expansion satisfies the semiclassical diagrammatic rules for the calculation of transport statistics. One of the virtues of this approach is that it leads very naturally to the semiclassical derivation of universal predictions from random matrix theory.     

二维柱坐标系辐射输运方程保球对称的离散纵标格式

 离散纵标格式是计算辐射输运方程的常用格式之一. 但是, 传统的离散纵标格式求解二维柱坐标系辐射输运方程模拟一维球对称问题时, 会出现明显的非对称现象, 球对称性被破坏. 针对该问题, 本文分析了传统离散纵标格式不能够保持球对称性的原因, 提出了空间基于柱坐标系、方向基于球坐标系的辐射输运方程, 并对该方程设计了新的离散纵标格式, 从理论上证明了当空间网格取球对称剖分时该离散格式能够保持一维球对称性的充分必要条件. 通过对真空球区域辐射输运、与物质耦合辐射输运等球对称算例的数值模拟, 验证了该格式的保球对称性, 球对称误差能够达到机器精度. 非对称辐射驱动模型以及非对称网格剖分条件下的数值模拟等算例也取得了较好的结果.     

Electrochemical energy for living systems

Plastoquinone and ubiquinone play essential roles in the electron transport chains of chloroplasts and mitochondria by coupling electron transport to the transfer of protons across membranes. The energy of the resulting proton gradient is used to synthesize adenosine triphosphate (ATP), the energy currency of all life. How did quinones first become involved in this process? We have detected several quinone compounds in carbonaceous meteorites that can transport protons in a liposome model system. It is possible that such compounds were available to transport protons in primitive versions of electron transport in early life.     

Charge transport in anodic TiO2 nanotubes studied by terahertz spectroscopy

We report on the photoelectrochemical and terahertz measurements, of the charge transport properties of 1 μm thick self‐organized TiO₂ nanotube layers, prepared by the anodization of titanium. We provide evidence regarding the complexity of electron transport, and dynamics in the nanotubes. Shortly after photoexcitation, charge mobilites in amorphous and crystalline nanotubes are similar, but still lower compared to the bulk anatase. The mobility subsequently decreases due to trapping‐detrapping processes. The recombination rate in anatase nanotubes is much slower than in the amorphous ones, enabling the material to reach an internal photon to electron conversion efficiency exceeding 60%.     

Single-electron coherence: Finite temperature versus pure dephasing

We analyze a coherent injection of single electrons on top of the Fermi sea in two situations, at finite-temperature and in the presence of pure dephasing. Both finite-temperature and pure dephasing change the property of the injected quantum states from pure to mixed. However, we show that the temperature-induced mixedness does not alter the coherence properties of these single-electron states. In particular two such mixed states exhibit perfect antibunching while colliding at an electronic wave splitter. This is in striking difference with the dephasing-induced mixedness which suppresses antibunching. On the contrary, a single-particle shot noise is suppressed at finite temperatures but is not affected by pure dephasing. This work therefore extends the investigation of the coherence properties of single-electron states to the case of mixed states and clarifies the difference between different types of mixedness.     

Reprint of : Single-electron coherence: Finite temperature versus pure dephasing

We analyze a coherent injection of single electrons on top of the Fermi sea in two situations, at finite-temperature and in the presence of pure dephasing. Both finite-temperature and pure dephasing change the property of the injected quantum states from pure to mixed. However, we show that the temperature-induced mixedness does not alter the coherence properties of these single-electron states. In particular two such mixed states exhibit perfect antibunching while colliding at an electronic wave splitter. This is in striking difference with the dephasing-induced mixedness which suppresses antibunching. On the contrary, a single-particle shot noise is suppressed at finite temperatures but is not affected by pure dephasing. This work therefore extends the investigation of the coherence properties of single-electron states to the case of mixed states and clarifies the difference between different types of mixedness.