General theory of feedback control of a nuclear spin ensemble in quantum dots

We present a microscopic theory of the nonequilibrium nuclear spin dynamics driven by the electron and/or hole under continuous wave pumping in a quantum dot. We show the correlated dynamics of the nuclear spin ensemble and the electron and/or hole under optical excitation as a quantum feedback loop and investigate the dynamics of the many nuclear spins as a nonlinear collective motion. This gives rise to three observable effects: (i) hysteresis, (ii) locking (avoidance) of the pump absorption strength to (from) the natural resonance, and (iii) suppression (amplification) of the fluctuation of weakly polarized nuclear spins, leading to prolonged (shortened) electron spin coherence time. A single nonlinear feedback function as a "measurement" of the nuclear field operator in the quantum feedback loop is constructed which determines the different outcomes of the three effects listed above depending on the feedback being negative or positive. The general theory also helps to put in perspective the wide range of existing theories on the problem of a single electron spin in a nuclear spin bath.Comment: 20 pages, 7 figure

The Two-Boson-Exchange Correction to Parity-Violating Elastic Electron-Proton Scattering

We calculate the two-boson-exchange (TBE) corrections to the parity-violating asymmetry of the elastic electron-proton scattering in a simple hadronic model including the nucleon and the $\Delta(1232)$ intermediate states. We find that $\Delta$ contribution $\delta_\Delta$ is, in general, comparable with the nucleon contribution $\delta_N$ and the current experimental measurements of strange-quark effects in the proton neutral weak current. The total TBE corrections to the current extracted values of $G^{s}_{E}+\beta G^{s}_{M}$ in recent experiments are found to lie in the range of $-7\sim +7$.Comment: 3 pages, 2 figs, 1 table, talk given at International Conference of Particle and Nuclei (PANIC08) Eilat, Israel, 9-14 Nov,200

Partition function of the eight-vertex model with domain wall boundary condition

We derive the recursive relations of the partition function for the eight-vertex model on an $N\times N$ square lattice with domain wall boundary condition. Solving the recursive relations, we obtain the explicit expression of the domain wall partition function of the model. In the trigonometric/rational limit, our results recover the corresponding ones for the six-vertex model.Comment: Latex file, 20 pages; V2, references adde

Finite Temperature Behavior of the ν=1\nu=1 Quantum Hall Effect in Bilayer Electron Systems

An effective field theoretic description of $\nu=1$ bilayer electron systems stabilized by Coulomb repulsion in a single wide quantum well is examined using renormalization group techniques. The system is found to undergo a crossover from a low temperature strongly correlated quantum Hall state to a high temperature compressible state. This picture is used to account for the recent experimental observation of an anomalous transition in bilayer electron systems (T. S. Lay, {\em et al.} Phys. Rev. B {\bf 50}, 17725 (1994)). An estimate for the crossover temperature is provided, and it is shown that its dependence on electron density is in reasonable agreement with i the experiment.Comment: Corrected typos, and changed content, 5 pages and 2 figures, accepted in Phys. Rev.

Free field realization of the osp(2n∣2n)osp(2n|2n) current algebra

The $osp(2n|2n)$ current algebra for a {\it generic} positive integer $n$ at general level $k$ is investigated. Its free field representation and corresponding energy-momentum tensor are constructed. The associated screening currents of the first kind are also presented.Comment: Latex file; 21 pages; V2, typos corrected, the new version appears in Phys. Rev.

Integrated Data and Energy Communication Network: A Comprehensive Survey

OAPA In order to satisfy the power thirsty of communication devices in the imminent 5G era, wireless charging techniques have attracted much attention both from the academic and industrial communities. Although the inductive coupling and magnetic resonance based charging techniques are indeed capable of supplying energy in a wireless manner, they tend to restrict the freedom of movement. By contrast, RF signals are capable of supplying energy over distances, which are gradually inclining closer to our ultimate goal – charging anytime and anywhere. Furthermore, transmitters capable of emitting RF signals have been widely deployed, such as TV towers, cellular base stations and Wi-Fi access points. This communication infrastructure may indeed be employed also for wireless energy transfer (WET). Therefore, no extra investment in dedicated WET infrastructure is required. However, allowing RF signal based WET may impair the wireless information transfer (WIT) operating in the same spectrum. Hence, it is crucial to coordinate and balance WET and WIT for simultaneous wireless information and power transfer (SWIPT), which evolves to Integrated Data and Energy communication Networks (IDENs). To this end, a ubiquitous IDEN architecture is introduced by summarising its natural heterogeneity and by synthesising a diverse range of integrated WET and WIT scenarios. Then the inherent relationship between WET and WIT is revealed from an information theoretical perspective, which is followed by the critical appraisal of the hardware enabling techniques extracting energy from RF signals. Furthermore, the transceiver design, resource allocation and user scheduling as well as networking aspects are elaborated on. In a nutshell, this treatise can be used as a handbook for researchers and engineers, who are interested in enriching their knowledge base of IDENs and in putting this vision into practice

Anomalous Exponent of the Spin Correlation Function of a Quantum Hall Edge

The charge and spin correlation functions of partially spin-polarized edge electrons of a quantum Hall bar are studied using effective Hamiltonian and bosonization techniques. In the presence of the Coulomb interaction between the edges with opposite chirality we find a different crossover behavior in spin and charge correlation functions. The crossover of the spin correlation function in the Coulomb dominated regime is characterized by an anomalous exponent, which originates from the finite value of the effective interaction for the spin degree of freedom in the long wavelength limit. The anomalous exponent may be determined by measuring nuclear spin relaxation rates in a narrow quantum Hall bar or in a quantum wire in strong magnetic fields.Comment: 4 pages, Revtex file, no figures. To appear in Physical Revews B, Rapid communication