Efficient and long-lived quantum memory with cold atoms inside a ring cavity

Quantum memories are regarded as one of the fundamental building blocks of linear-optical quantum computation and long-distance quantum communication. A long standing goal to realize scalable quantum information processing is to build a long-lived and efficient quantum memory. There have been significant efforts distributed towards this goal. However, either efficient but short-lived or long-lived but inefficient quantum memories have been demonstrated so far. Here we report a high-performance quantum memory in which long lifetime and high retrieval efficiency meet for the first time. By placing a ring cavity around an atomic ensemble, employing a pair of clock states, creating a long-wavelength spin wave, and arranging the setup in the gravitational direction, we realize a quantum memory with an intrinsic spin wave to photon conversion efficiency of 73(2)% together with a storage lifetime of 3.2(1) ms. This realization provides an essential tool towards scalable linear-optical quantum information processing.Comment: 6 pages, 4 figure

QUALIDADE DO VINHO PRODUZIDO NO MUNICÍPIO DE COLOMBO NA SAFRA 2001

O presente trabalho faz parte da segunda etapa do Projeto de Extensão No 248/PROEC MELHORIA DA QUALIDADE DO VINHO PRODUZIDO NO MUNICÍPIO DE COLOMBO, com a finalidade de acompanhar e avaliar os resultados da implantação de procedimentos de modernização da tecnologia, identificados como mais adequados durante a realização do curso Elaboração de Vinhos, ministrado como parte integrante da primeira etapa do projeto. Após o trabalho em campo, com visitas às diversas vinícolas, foram realizadas análises físico-químicas das diferentes amostras de vinhos, cujos resultados foram comparados com os padrões fixados pelo Ministério da Agricultura. QUALITY OF THE WINE PRODUCED IN COLOMBO CITY IN HARVEST OF 2001 Abstract The present paper is part of the second phase of the Extension Project nº 248/PROEC IMPROVEMENT OF QUALITY OF THE WINE PRODUCED IN COLOMBO CITY and shows the results of the implantation of modern technological wine making procedures on small wineries of Colombo City. On the first phase of project, themost appropriate techniques were identified during a course on WINE MAKING presented to winemakers of the region. On the second phase, besides visiting small wineries, physical and chemical analyses were carried out on several wine samples and the results were compared with patterns established by the Brazilian Ministry of Agriculture

Evaluation of an efficiency-optimized calculation of PM synchronous machines' operating range using time-saving numerical and analytical coupling

In this paper, a new method for an accurate and also time-saving calculation of permanent magnet synchronous machines is presented. The method is based on a coupled numerical-analytical approach. The aim is to determine efficiency optimized torque-speed characteristics of the drive system. The novel approach considers all kinds of losses, such as switching and conduction losses of the inverter, copper losses, friction losses as well as saturation-dependent hysteresis and eddy current losses of the electrical machine. The presented approach is verified by measurements of a high-torque wheel hub drive