A non-Markovian optical signature for detecting entanglement in coupled excitonic qubits

We identify an optical signature for detecting entanglement in experimental nanostructure systems comprising coupled excitonic qubits. This signature owes its strength to non-Markovian dynamical effects in the second-order temporal coherence function of the emitted radiation. We calculate autocorrelation and cross-correlation functions for both selective and collective light excitation, and prove that the coherence properties of the emitted light do indeed carry information about the entanglement of the initial multi-qubit state. We also show that this signature can survive in the presence of a noisy environment.Comment: 4 pages, 4 color figures. Minor changes. Accepted version to be published in Europhysics Letter

Search for interactions between ejections of GRS 1915+105 and its environment

To unravel the effect of likely interactions between the energetic ejections of the galactic superluminal source GRS 1915+105 and its surrounding interstellar medium, we observed its environment. Two IRAS sources are symmetrically placed with respect to GRS 1915+105, and are aligned with the sub-arcsec ejections of this source. We analyzed these two sources IRAS 19124+1106 and IRAS 19132+1035 through near-infrared, millimeter and centimeter wavelengths. The evidence for these regions being interaction zones seems inconclusive.Comment: 4 pages, 3 figures, to appear in Proceedings of X-ray Astronomy '999 - Stellar Endpoints, AGN and the Diffuse Background, 2000. G. Malaguti, G. Palumbo & N. White (eds), Gordon & Breach (Singapore

The planetary nebula nature and properties of IRAS18197-1118

IRAS18197-1118 is a stellar-like object that has been classified as a planetary nebula from its radio continuum emission and high [SIII]9532 to Paschen9 line intensity ratio, as derived from direct images. We present intermediate- and high-resolution, optical spectroscopy, VLA 8.46 GHz radio continuum data, and narrow-band optical images of IRAS18197-1118 aimed at confirming its planetary nebula nature, and analyzing its properties. The optical spectrum shows that IRAS18197-1118 is a medium-excitation planetary nebula suffering a high extinction (c(H_beta) ~3.37). The optical images do not resolve the object but the 8.46 GHz image reveals an elliptical shell of ~2.7x1.6 arcsec^2 in size, a compact central nebular region, and possible bipolar jet-like features, indicating several ejection events. The existence of a compact central nebula makes IRAS18197-1118 singular because this kind of structure is observed in a few PNe only. An expansion velocity ~20 km/s and a systemic velocity (LSR) ~+95 km/s are obtained for the object. An electron density of ~3.4x10^4 cm-3 and an ionized mass of ~2.1x10^-2 M_sun are deduced from the 8.46 GHz radio continuum data for an estimated statistical distance of 6 kpc. Helium abundance is high but nitrogen is not enriched, which is not consistently reproduced by evolutionary models, suggesting different abundances in the elliptical shell and central region. The properties of IRAS18197-1118 indicate a relatively young planetary nebula, favor a distance of >~6 kpc, and strongly suggest that it is an inner-disc planetary nebula.Comment: Accepted by MNRAS. 8 pages, 5 figures, 4 table

High Angular Resolution Observations of the Collimated Jet Source Associated with a Massive Protostar in IRAS 16547-4247

A triple radio source recently detected in association with the luminous infrared source IRAS 16547-4247 has been studied with high angular resolution and high sensitivity with the Very Large Array at 3.6 and 2 cm. Our observations confirm the interpretation that the central object is a thermal radio jet, while the two outer lobes are most probably heavily obscured HH objects. The thermal radio jet is resolved angularly for the first time and found to align closely with the outer lobes. The opening angle of the thermal jet is estimated to be $\sim 25^\circ$, confirming that collimated outflows can also be present in massive protostars. The proper motions of the outer lobes should be measurable over timescales of a few years. Several fainter sources detected in the region are most probably associated with other stars in a young cluster.Comment: 9 pages, 2 figure

Repeated Relativistic Ejections in GRS 1915+105

In 1994 February-August we observed with the VLA four ejection events of radio emitting clouds from the high energy source GRS 1915+105. These events are all consistent with anti-parallel ejections of twin pairs of clouds moving away from the compact source at $\sim$ 0.92 of the speed of light and angles of $\sim$ 70$^{\circ}$ with respect to the line of sight. The flux ratios and time evolution of the expelled clouds are consistent with actual motions of the radiating matter rather than with the simple propagation of pulses in a medium moving at slower velocities. The large kinetic power of the sudden, short, and rather discontinuous ejections exceeds by more than an order of magnitude the maximum steady photon luminosity of the source, suggesting that in GRS 1915+105 a radiation acceleration mechanism of the ejecta is unlikely. As in other galactic and extragalactic radio sources, the decrease in flux density as a function of angular separation from the central source shows a steepening with distance. Additional ejection events have been observed in 1995 and 1997 and we compare them with the 1994 events.Comment: 20 pages, 7 figures. To appear in The Astrophysical Journal, January 10, 1999 issu