Test of quantum nonlocality for cavity fields

There have been studies on formation of quantum-nonlocal states in spatially separate two cavities. We suggest a nonlocal test for the field prepared in the two cavities. We couple classical driving fields with the cavities where a nonlocal state is prepared. Two independent two-level atoms are then sent through respective cavities to interact off-resonantly with the cavity fields. The atomic states are measured after the interaction. Bell's inequality can be tested by the joint probabilities of two-level atoms being in their excited or ground states. We find that quantum nonlocality can also be tested using a single atom sequentially interacting with the two cavities. Potential experimental errors are also considered. We show that with the present experimental condition of 5% error in the atomic velocity distribution, the violation of Bell's inequality can be measured.Comment: 14pages, 2figures. accepted to Phys. Rev.

Realization of a superconducting atom chip

We have trapped rubidium atoms in the magnetic field produced by a superconducting atom chip operated at liquid Helium temperatures. Up to $8.2\cdot 10^5$ atoms are held in a Ioffe-Pritchard trap at a distance of 440 $\mu$m from the chip surface, with a temperature of 40 $\mu$K. The trap lifetime reaches 115 s at low atomic densities. These results open the way to the exploration of atom--surface interactions and coherent atomic transport in a superconducting environment, whose properties are radically different from normal metals at room temperature.Comment: Submitted to Phys. Rev. Let

Entanglement of a Mesoscopic Field with an Atom induced by Photon Graininess in a Cavity

We observe that a mesoscopic field made of several tens of microwave photons exhibits quantum features when interacting with a single Rydberg atom in a high-Q cavity. The field is split into two components whose phases differ by an angle inversely proportional to the square root of the average photon number. The field and the atomic dipole are phase-entangled. These manifestations of photon graininess vanish at the classical limit. This experiment opens the way to studies of large Schrodinger cat states at the quantum-classical boundary

High-resolution spatial mapping of a superconducting NbN wire using single-electron detection

Superconducting NbN wires have recently received attention as detectors for visible and infrared photons. We present experiments in which we use a NbN wire for high-efficiency (40 %) detection of single electrons with keV energy. We use the beam of a scanning electron microscope as a focussed, stable, and calibrated electron source. Scanning the beam over the surface of the wire provides a map of the detection efficiency. This map shows features as small as 150 nm, revealing wire inhomogeneities. The intrinsic resolution of this mapping method, superior to optical methods, provides the basis of a characterization tool relevant for photon detectors.Comment: 2009 IEEE Toronto International Conference, Science and Technology for Humanity (TIC-STH

Generating and probing a two-photon Fock state with a single atom in a cavity

A two-photon Fock state is prepared in a cavity sustaining a "source mode " and a "target mode", with a single circular Rydberg atom. In a third-order Raman process, the atom emits a photon in the target while scattering one photon from the source into the target. The final two-photon state is probed by measuring by Ramsey interferometry the cavity light shifts induced by the target field on the same atom. Extensions to other multi-photon processes and to a new type of micromaser are briefly discussed

Monotonic properties of the shift and penetration factors

We study derivatives of the shift and penetration factors of collision theory with respect to energy, angular momentum, and charge. Definitive results for the signs of these derivatives are found for the repulsive Coulomb case. In particular, we find that the derivative of the shift factor with respect to energy is positive for the repulsive Coulomb case, a long anticipated but heretofore unproven result. These results are closely connected to the properties of the sum of squares of the regular and irregular Coulomb functions; we also present investigations of this quantity.Comment: 13 pages, 1 figur

In situ observations of ClO in the Antarctic: Evidence for chlorine catalyzed destruction of ozone

Results from a series of 12 ER-2 aircraft flights into the Antarctic polar vortex are summarized. These in situ data define the spatial and temporal distribution of ClO as the aircraft flew at an altitude of approx. 18 km from Punta Arenas (54 deg S latitude) to the base of the Palmer Peninsula (72 deg S latitude), executed a rapid descent to approx. 13 km, turned north and climbed bach to approximately 18 km, returning to Punta Arenas. A general pattern in the ClO distribution is reported: mixing ratios of approximately 10 ppt are found at altitude in the vicinity of 55 deg S increasing to 50 ppt at 60 degrees S. In the vicinity of 65 deg S latitude a steep gradient in the ClO mixing ratio is observed. At a fixed potential temperature, the ClO mixing ratio through this sharp transition increases by an order of magnitude within a very few degrees of latitude, thus defining the edge of the chemical containment vessel. From the edge of that containment vessel to the southern extension of the flights, 72 deg S, a dome of slowly increasing ClO best describes the distribution. Conclusion are drawn from the data

The geomorphological setting of some of Scotland's east coast freshwater mills: a comment on Downward and Skinner (2005) ‘Working rivers: the geomorphological legacy...’

Many of the water mills on Scotland's east coast streams, unlike those discussed recently by Downward and Skinner (2005 Area 37 138–47), are found in predominantly bedrock reaches immediately downstream of knickpoints (i.e. bedrock steps). Bedrock knickpoints in the lower reaches of Scottish rivers are a widespread fluvial response to the glacio-isostatic rebound of northern Britain. These steps in the river profile propagate headward over time, but for intervals of a few centuries or so they are sufficiently stable to be exploited for the elevational fall necessary to power the mill wheel. Many of these mills were apparently powered by ‘run-of-the-river’, as are some today that formerly had mill dams. The typical lack of sediment storage along the erosional lower reaches of many Scottish rivers means that failure of mill structures in Scotland will probably have less dramatic geomorphological and management implications than those suggested by Downward and Skinner for southern English rivers