Floquet engineering of long-range p-wave superconductivity: Beyond the high-frequency limit

It has been shown that long-range {\it p}-wave superconductivity in a Kitaev chain can be engineered via an ac field with a high frequency [Benito et al., Phys. Rev. B 90, 205127 (2014)]. For its experimental realization, however, theoretical understanding of Floquet engineering with a broader range of driving frequencies becomes important. In this work, focusing on the ac-driven tunneling interactions of a Kitaev chain, we investigate effects from the leading correction to the high-frequency limit on the emergent {\it p}-wave superconductivity. Importantly, we find new engineered long-range {\it p}-wave pairing interactions that can significantly alter the ones in the high-frequency limit at long interaction ranges. We also find that the leading correction additionally generates nearest-neighbor {\it p}-wave pairing interactions with a renormalized pairing energy, long-range tunneling interactions, and in particular multiple pairs of Floquet Majorana edge states that are destroyed in the high- frequency limit.Comment: 13 pages, 8 figure

Physical Sputtering of Metallic Systems by Charged-Particle Impact

The present paper provides a brief overview of our current understanding of physical sputtering by charged-particle impact, with the emphasis on sputtering of metals and alloys under bombardment with particles that produce knock-on collisions. Fundamental aspects of ion-solid interactions, and recent developments in the study of sputtering of elemental targets and preferential sputtering in multicomponent materials are reviewed. We concentrate only on a few specific topics of sputter emission, including the various properties of the sputtered flux and depth of origin, and on connections between sputtering and other radiation-induced and -enhanced phenomena that modify the near-surface composition of the target. The synergistic effects of these diverse processes in changing the composition of the integrated sputtered-atom flux is described in simple physical terms, using selected examples of recent important progress

H∞Model Approximation for Discrete-time Markovian Jump Systems with Mode-dependent Time Delays

This paper considers the problem of computing an approximation system for a discrete-time Markovian jump system with mode-dependent time delays such that the H∞norm of the error system is less than a prescribed scalar. It can be shown that the approximation system is constructed by the solutions of linear matrix inequalities (LMIs) with inverse constraints. An efficient algorithm is used to obtain the approximation system and an example is employed to demonstrate the effectiveness of the model approximation algorithm.published_or_final_versio

Backaction of a charge detector on a double quantum dot

We develop a master equation approach to study the backaction of quantum point contact (QPC) on a double quantum dot (DQD) at zero bias voltage. We reveal why electrons can pass through the zero-bias DQD only when the bias voltage across the QPC exceeds a threshold value determined by the eigenstate energy difference of the DQD. This derived excitation condition agrees well with experiments on QPC-induced inelastic electron tunneling through a DQD [S. Gustavsson et al., Phys. Rev. Lett. 99, 206804(2007)]. Moreover, we propose a new scheme to generate a pure spin current by the QPC in the absence of a charge current.Comment: 6 pages, 4 figure

A Data Structure Using Hashing and Tries For Efficient Chinese Lexical Access

A lexicon is needed in many applications. In the past, different structures such as tries, hash tables and their variants have been investigated for lexicon organization and lexical access. In this paper, we propose a new data structure that combines the use of hash table and tries for storing a Chinese lexicon. The data structure facilitates an efficient lexical access yet requires less memory than that of a trie lexicon. Experiments are conducted to evaluate its performance for in-vocabulary lexical access, out-of-vocabulary word rejection, and substring matching. The effectiveness of the proposed approach is confirmed.published_or_final_versio

Delay-dependent L2-L∞ model reduction for polytopic systems with time-varying delay

This paper considers the L2-L∞ model reduction problems for polytopic system with time-varying delay. In terms of the solution of linear matrix inequalities (LMIs) and inverse constraints, sufficient conditions are presented to construct the reduced order models such that the L2-L∞ gain of the error system between the full order model and the reduced order one is less than a given scalar.published_or_final_versio