Robert J. Brecha

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We report on the Bose-Einstein condensation of potassium atoms, whereby quantum degeneracy is achieved by sympathetic cooling with evaporatively cooled rubidium. Because of the rapid thermalization of the two different atoms, the efficiency of the cooling process is high. The ability to achieve condensation by sympathetic cooling with a different species(More)
The events of March 2011 at the nuclear power complex in Fukushima, Japan, raised questions about the safe operation of nuclear power plants, with early retirement of existing nuclear power plants being debated in the policy arena and considered by regulators. Also, the future of building new nuclear power plants is highly uncertain. Should nuclear power(More)
A degenerate gas of identical fermions is brought to collapse by the interaction with a Bose-Einstein condensate. We used an atomic mixture of fermionic potassium-40 and bosonic rubidium-87, in which the strong interspecies attraction leads to an instability above a critical number of particles. The observed phenomenon suggests a direction for manipulating(More)
An experimental demonstration of a noninvasive optical probe of magnetic fields is presented. The technique used is magnetic rotation spectroscopy of the b(1)?(g)(+) - X(3)?(g)(-) band of oxygen near 760 nm. Ambient concentrations of oxygen at atmospheric pressure are sufficient to observe substantial signals. In addition, a diode laser is used as the light(More)
We investigate the photon statistics of the light transmitted from a driven optical cavity containing N two-level atoms, with emphasis on the weak driving field limit. This limit is of most interest from the point of view of quantum fluctuations. We find that various types of nonclassical behavior are possible, even with large numbers of atoms in the(More)
Global surface temperature has increased markedly over the last 100 years. This increase has a variety of implications for human societies, and for ecological systems. One of the most obvious ways ecosystems are affected by global climate change is through alteration of organisms’ developmental timing (phenology). We used annual botanical surveys that(More)
We introduce a new method for incorporating short-term temporal variability of both power demand and variable renewables (VRE) into long-term energy-economy models: the RLDC approach. The core of the implementation is a representation of residual load duration curves (RLDCs), which change endogenously depending on the share and mix of VRE. The approach(More)