Generation and purification of maximally-entangled atomic states in optical cavities

We present a probabilistic scheme for generating and purifying maximally-entangled states of two atoms inside an optical cavity via no-photon detection in the output cavity mode, where ideal detectors may not be required. The intermediate mixed states can be continuously "filtered" so as to violate Bell inequalities in a parametrized manner. The scheme relies on an additional strong-driving field that yields unusual dynamics in cavity QED experiments, simultaneously realizing Jaynes-Cummings and anti-Jaynes-Cummings interactions.Comment: 4 pages and 3 figure

Instantaneous Measurement of field quadrature moments and entanglement

We present a method of measuring expectation values of quadrature moments of a multimode field through two-level probe ``homodyning''. Our approach is based on an integral transform formalism of measurable probe observables, where analytically derived kernels unravel efficiently the required field information at zero interaction time, minimizing decoherence effects. The proposed scheme is suitable for fields that, while inaccessible to a direct measurement, enjoy one and two-photon Jaynes-Cummings interactions with a two-level probe, like spin, phonon, or cavity fields. Available data from previous experiments are used to confirm our predictions.Comment: 4 pages, no figures, modified version with experimental estimation

Structure of the cell envelope of Halobacterium halobium

The structure of the isolated cell envelope of Halobacterium halobium is studied by X-ray diffraction, electron microscopy, and biochemical analysis. The envelope consists of the cell membrane and two layers of protein outside. The outer layer of protein shows a regular arrangement of the protein or glycoprotein particles and is therefore identified as the cell wall. Just outside the cell membrane is a 20 A-thick layer of protein. It is a third structure in the envelope, the function of which may be distinct from that of the cell membrane and the cell wall. This inner layer of protein is separated from the outer protein layer by a 65 Å-wide space which has an electron density very close to that of the suspending medium, and which can be etched after freeze-fracture. The space is tentatively identified as the periplasmic space. At NaCl concentrations below 2.0 M, both protein layers of the envelope disintegrate. Gel filtration and analytical ultracentrifugation of the soluble components from the two protein layers reveal two major bands of protein with apparent mol wt of ~16,000 and 21,000. At the same time, the cell membrane stays essentially intact as long as the Mg++ concentration is kept at ≥ 20 mM. The cell membrane breaks into small fragments when treated with 0.1 M NaCl and EDTA, or with distilled water, and some soluble proteins, including flavins and cytochromes, are released. The cell membrane apparently has an asymmetric core of the lipid bilayer

Strong-driving-assisted multipartite entanglement in cavity QED

We propose a method of generating multipartite entanglement by considering the interaction of a system of N two-level atoms in a cavity of high quality factor with a strong classical driving field. It is shown that, with a judicious choice of the cavity detuning and the applied coherent field detuning, vacuum Rabi coupling produces a large number of important multipartite entangled states. It is even possible to produce entangled states involving different cavity modes. Tuning of parameters also permits us to switch from Jaynes-Cummings to anti-Jaynes-Cummings like interaction.Comment: Last version with minor changes and added references. Accepted for publication in Phys. Rev. Letter

Assessment of crash fire hazard of LH sub 2 fueled aircraft

The relative safety of passengers in LH2 - fueled aircraft, as well as the safety of people in areas surrounding a crash scene, has been evaluated in an analytical study. Four representative circumstances were postulated involving a transport aircraft in which varying degrees of severity of damage were sustained. Potential hazard to the passengers and to the surroundings posed by the spilled fuel was evaluated for each circumstance. Corresponding aircraft fueled with liquid methane, Jet A, and JP-4 were also studied in order to make comparisons of the relative safety. The four scenarios which were used to provide a basis for the evaluation included: (1) a small fuel leak internal to the aircraft, (2) a survivable crash in which a significant quantity of fuel is spilled in a radial pattern as a result of impact with a stationary object while taxiing at fairly low speed, (3) a survivable crash in which a significant quantity of fuel is spilled in an axial pattern as a result of impact during landing, and (4) a non-survivable crash in which a massive fuel spill occurs instantaneously

Measure of phonon-number moments and motional quadratures through infinitesimal-time probing of trapped ions

A method for gaining information about the phonon-number moments and the generalized nonlinear and linear quadratures in the motion of trapped ions (in particular, position and momentum) is proposed, valid inside and outside the Lamb-Dicke regime. It is based on the measurement of first time derivatives of electronic populations, evaluated at the motion-probe interaction time t=0. In contrast to other state-reconstruction proposals, based on measuring Rabi oscillations or dispersive interactions, the present scheme can be performed resonantly at infinitesimal short motion-probe interaction times, remaining thus insensitive to decoherence processes.Comment: 10 pages. Accepted in JPhys

Quantum computation with trapped ions in an optical cavity

Two-qubit logical gates are proposed on the basis of two atoms trapped in a cavity setup. Losses in the interaction by spontaneous transitions are efficiently suppressed by employing adiabatic transitions and the Zeno effect. Dynamical and geometrical conditional phase gates are suggested. This method provides fidelity and a success rate of its gates very close to unity. Hence, it is suitable for performing quantum computation.Comment: 4 pages, 5 figures, REVTEX, second part modified, typos correcte