Phonon Josephson Junction with Nanomechanical Resonators

We study coherent phonon oscillations and tunneling between two coupled nonlinear nanomechanical resonators. We show that the coupling between two nanomechanical resonators creates an effective phonon Josephson junction which exhibits two different dynamical behaviors: Josephson oscillation (phonon-Rabi oscillation) and macroscopic self-trapping (phonon blockade). Self-trapping originates from mechanical nonlinearities, meaning that when the nonlinearity exceeds its critical value, the energy exchange between the two resonators is suppressed, and phonon-Josephson oscillations between them are completely blocked. An effective classical Hamiltonian for the phonon Josephson junction is derived and its mean-field dynamics is studied in phase space. Finally, we study the phonon-phonon coherence quantified by the mean fringe visibility, and show that the interaction between the two resonators may lead to the loss of coherence in the phononic junction.Comment: Realization of Josephson junction at nano/optomechanical resonators. Comments are welcome

Continuous-variable dense coding by optomechanical cavities

In this paper, we show how continuous-variable dense coding can be implemented using entangled light generated from a membrane-in-the-middle geometry. The mechanical resonator is assumed to be a high reflectivity membrane hung inside a high quality factor cavity. We show that the mechanical resonator is able to generate an amount of entanglement between the optical modes at the output of the cavity, which is strong enough to approach the capacity of quantum dense coding at small photon numbers. The suboptimal rate reachable by our optomechanical protocol is high enough to outperform the classical capacity of the noiseless quantum channel

A new species of the genus Gomphomastax Brunner von Wattenwyl (Orthoptera: Eumastacidae: Gomphomastacinae) from Indian Kashmir

A new species, Gomphomastax nigrovittata Usmani, from Kashmir is described and illustrated. In addition to conventional morphological characters, genitalic structures are also studied. A key to known species of Gomphomastax from Indian Kashmir is given

ACTION RESEARCH ON IMPROVING STUDENTS’ MOTIVATION IN SPEAKING THROUGH CONTEXTUAL TEACHING LEARNING

This study investigated students’ motivation in speaking through Contextual Teaching Learning at a Junior High School in Jampang Kulon, West Java. The procedures of action research (plan, act, observe, reflect, and revise) were used to investigate the participants’ learning activities and motivation. The study was conducted in two cycles involving two on-site English teachers. Data were collected through the teacher’s journal, observers’ sheets, students’ diaries, and questionnaires. The results of the research indicated that students’ motivation in speaking could be improved through activating the students’ needs of competence, autonomy, and relatedness. Finally, the results of the study are expected to have a contribution to developing students to be motivated language learners