Experimental demonstration of composite stimulated Raman adiabatic passage

We experimentally demonstrate composite stimulated Raman adiabatic passage (CSTIRAP), which combines the concepts of composite pulse sequences and adiabatic passage. The technique is applied for population transfer in a rare-earth doped solid. We compare the performance of CSTIRAP with conventional single and repeated STIRAP, either in the resonant or the highly detuned regime. In the latter case, CSTIRAP improves the peak transfer efficiency and robustness, boosting the transfer efficiency substantially compared to repeated STIRAP. We also propose and demonstrate a universal version of CSTIRAP, which shows improved performance compared to the originally proposed composite version. Our findings pave the way towards new STIRAP applications, which require repeated excitation cycles, e.g., for momentum transfer in atom optics, or dynamical decoupling to invert arbitrary superposition states in quantum memories.Comment: 11 pages, 5 figure

A CMOS 100 MHz continuous-time seventh order 0.05° equiripple linear phase leapfrog multiple loop feedback Gm-C filter

“This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder." “Copyright IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.”A novel 100 MHz CMOS Gm-C seventh-order 0.05° equiripple linear phase low-pass multiple loop feedback (MLF) filter based on leapfrog (LF) topology is presented. The filter is implemented using a fully-differential linear, high performance operational transconductance amplifier (OTA) based on cross-coupled pairs. PSpice simulations in a standard TSMC 0.25 μm CMOS process and with a single 5 V power supply have shown that the cut-off frequency of the filter without and with gain boost ranges from 8-32 MHz and 15-100 MHz, respectively. With gain boost, total harmonic distortion (THD) for a differential input voltage Vid of 315 mVpp at 1 MHz is less than -40 dB, dynamic range at 1% THD is over 55 dB, output noise with bandwidth 500 MHz is only 300 μVRMS, and power consumption is 322 mW

Optimized Performance Evaluation of LTE Hard Handover Algorithm with Average RSRP Constraint

Hard handover mechanism is adopted to be used in 3GPP Long Term Evolution (3GPP LTE) in order to reduce the complexity of the LTE network architecture. This mechanism comes with degradation in system throughput as well as a higher system delay. This paper proposes a new handover algorithm known as LTE Hard Handover Algorithm with Average Received Signal Reference Power (RSRP) Constraint (LHHAARC) in order to minimize number of handovers and the system delay as well as maximize the system throughput. An optimized system performance of the LHHAARC is evaluated and compared with three well-known handover algorithms via computer simulation. The simulation results show that the LHHAARC outperforms three well-known handover algorithms by having less number of average handovers per UE per second, shorter total system delay whilst maintaining a higher total system throughput.Comment: 16 pages, 9 figures, International Journal of Wireless & Mobile Networks (IJWMN

Universal Three Dimensional Optical Logic

Modern integrated circuits are essentially two-dimensional (2D). Partial three-dimensional (3D) integration and 3D-transistor-level integrated circuits have long been anticipated as routes to improve the performance, cost and size of electronic computing systems. Even as electronics approach fundamental limits however, stubborn challenges in 3D circuits, and innovations in planar technology have delayed the dimensional transition. Optical computing offers potential for new computing approaches, substantially greater performance and would complement technologies in optical interconnects and data storage. Nevertheless, despite some progress, few proposed optical transistors possess essential features required for integration into real computing systems. Here we demonstrate a logic gate based on universal features of nonlinear wave propagation: spatiotemporal instability and collapse. It meets the scaling criteria and enables a 3D, reconfigurable, globally-hyperconnected architecture that may achieve an exponential speed up over conventional platforms. It provides an attractive building block for future optical computers, where its universality should facilitate flexible implementations.Comment: manuscript (5 pages, 3 figures) with supplementary information (6 pages, 5 figures