Slowly modulated oscillations in nonlinear diffusion processes

It is shown here that certain systems of nonlinear (parabolic) reaction-diffusion equations have solutions which are approximated by oscillatory functions in the form R(ξ - cτ)P(t^*) where P(t^*) represents a sinusoidal oscillation on a fast time scale t* and R(ξ - cτ) represents a slowly-varying modulating amplitude on slow space (ξ) and slow time (τ) scales. Such solutions describe phenomena in chemical reactors, chemical and biological reactions, and in other media where a stable oscillation at each point (or site) undergoes a slow amplitude change due to diffusion

Non-Local Quantum Gates: a Cavity-Quantum-Electro-Dynamics implementation

The problems related to the management of large quantum registers could be handled in the context of distributed quantum computation: unitary non-local transformations among spatially separated local processors are realized performing local unitary transformations and exchanging classical communication. In this paper, we propose a scheme for the implementation of universal non-local quantum gates such as a controlled-\gate{NOT} (\cnot) and a controlled-quantum phase gate (\gate{CQPG}). The system we have chosen for their physical implementation is a Cavity-Quantum-Electro-Dynamics (CQED) system formed by two spatially separated microwave cavities and two trapped Rydberg atoms. We describe the procedures to follow for the realization of each step necessary to perform a specific non-local operation.Comment: 12 pages, 5 figures, RevTeX; extensively revised versio

Current understanding of SEP acceleration and transport

Through new missions and unusual solar conditions, solar cycle 24 has afforded the opportunity for expanding our understanding of solar energetic particle (SEP) acceleration and transport. With complementary SEP observations from multiple spacecraft separated significantly in longitude, it has been possible to examine the longitudinal distribution of energetic particles in individual events, rather than relying on statistical event studies. Unprecedented 360° views of the Sun, in multiple wavelengths and coronagraphs, has made it possible to identify solar source regions regardless of where they are located and to more accurately determine the properties of related coronal mass ejections. The unusually quiet conditions during the onset of cycle 24 allowed smaller SEP events to be examined and their source regions to be unambiguously identified. This paper reviews some of the unexpected results from multi-spacecraft SEP observations made over this solar cycle and discusses their implications for particle acceleration near the Sun and transport through the inner heliosphere

Multicomponent metal-organic framework membranes for advanced functional composites.

The diverse chemical and structural properties of metal-organic frameworks (MOFs) make them attractive for myriad applications, but their native powder form is limiting for industrial implementation. Composite materials of MOFs hold promise as a means of exploiting MOF properties in engineered forms for real-world applications. While interest in MOF composites is growing, research to date has largely focused on utilization of single MOF systems. The vast number of different MOF structures provides ample opportunity to mix and match distinct MOF species in a single composite to prepare multifunctional systems. In this work, we describe the preparation of three types of multi-MOF composites with poly(vinylidene fluoride) (PVDF): (1) co-cast MOF MMMs, (2) mixed MOF MMMs, and (3) multilayer MOF MMMs. Finally, MOF MMMs are explored as catalytic membrane reactors for chemical transformations

Detection of atomic entanglement and electromagnetically induced transparency in velocity-selective coherent population trapping

We investigate theoretically the optical properties of an atomic gas which has been cooled by the laser cooling method velocity-selective coherent population trapping. We demonstrate that the application of a weak laser pulse gives rise to a backscattered pulse, which is a direct signal for the entanglement in the atomic system, and which leads to single-particle entanglement on the few-photon level. If the pulse is applied together with the pump lasers, it also displays the phenomenon of electromagnetically induced transparency. We suggest that the effect should be observable in a gas of Rubidium atoms.Comment: Revtex, 9 pages, 6 figures. To appear in Physical Review