1,605 research outputs found
Electrical conductivity and thermal behavior of solid electrolytes based on alkali carbonates and sulfates
Both thermal stability and electrical conductivity of alkali ion conducting Na2CO3 and Na2SO4, were improved by adding alkaline earth carbonates and sulfates, respectively, as well as insulating materials like ¿-Al2O3. The admixing of divalent compounds causes two effects. First a more or less extended solution can exist depending on the radius of the alkaline earth ion and is accompanied by an increase in electrical conductivity. Secondly, a phase mixture with an excess of dopant was observed that shows an enhancement in conductivity and mechanical stability. This phenomenon known as composite effect was observed in the following systems: Na2CO3-BaCO3, Na2CO3-SrCO3, Na2SO4-BaSO4, Na2SO4-¿-Al2O3
Generation of field mediated three qubit entangled state shared by Alice and Bob
A scheme to generate shared tripartite entangled states, with two-trapped
atoms in a cavity held by Alice (qubits A1 and A2) entangled to a single
trapped atom in a remote lab owned by Bob (B), is proposed. The entanglement is
generated through interaction of trapped atoms with two mode squeezed light
shared by the two cavities. The proposed scheme is an extension of the proposal
of ref. [W. Son, M. S. Kim, J. Lee, and D. Ahn, J. Mod. Opt. 49, 1739 (2002)],
where the possibility of entangling two remote qubits using a bipartite
continuous variable state was examined. While the global negativity detects the
free entanglement of the three atom mixed state, the bound entanglement is
detected by the negativity calculated from pure state decomposition of the
state operator. The partial negativities calculated by selective partial
transposition of the three atom mixed state detect the pairwise entanglement of
qubit pairs A1B, A2B, and A1A2. The entanglement of three atoms is found to be
W-like, no GHZ like quantum correlations being generated.Comment: 14 pages, 06 figures, section IV revised, Other minor changes to
improve readabilit
Quantum random walk of two photons in separable and entangled state
We discuss quantum random walk of two photons using linear optical elements.
We analyze the quantum random walk using photons in a variety of quantum states
including entangled states. We find that for photons initially in separable
Fock states, the final state is entangled. For polarization entangled photons
produced by type II downconverter, we calculate the joint probability of
detecting two photons at a given site. We show the remarkable dependence of the
two photon detection probability on the quantum nature of the state. In order
to understand the quantum random walk, we present exact analytical results for
small number of steps like five. We present in details numerical results for a
number of cases and supplement the numerical results with asymptotic analytical
results
Multiphoton path entanglement by non-local bunching
Multiphoton path entanglement is created without applying post-selection, by
manipulating the state of stimulated parametric down-conversion. A specific
measurement on one of the two output spatial modes leads to the non-local
bunching of the photons of the other mode, forming the desired multiphoton path
entangled state. We present experimental results for the case of a heralded
two-photon path entangled state and show how to extend this scheme to higher
photon numbers.Comment: 4 pages, 5 figures, published versio
Experimental violation of a spin-1 Bell inequality using maximally-entangled four-photon states
We demonstrate the first experimental violation of a spin-1 Bell inequality.
The spin-1 inequality is a calculation based on the Clauser, Horne, Shimony and
Holt formalism. For entangled spin-1 particles the maximum quantum mechanical
prediction is 2.552 as opposed to a maximum of 2, predicted using local hidden
variables. We obtained an experimental value of 2.27 using the
four-photon state generated by pulsed, type-II, stimulated parametric
down-conversion. This is a violation of the spin-1 Bell inequality by more than
13 standard deviations.Comment: 5 pages, 3 figures, Revtex4. Problem with figures resolve
Quantum filter for non-local polarization properties of photonic qubits
We present an optical filter that transmits photon pairs only if they share
the same horizontal or vertical polarization, without decreasing the quantum
coherence between these two possibilities. Various applications for
entanglement manipulations and multi-photon qubits are discussed.Comment: 7 pages, including one figure, short discussion of error sources
adde
Dephasing of Mollow Triplet Sideband Emission of a Resonantly Driven Quantum Dot in a Microcavity
Detailed properties of resonance fluorescence from a single quantum dot in a
micropillar cavity are investigated, with particular focus on emission
coherence in dependence on optical driving field power and detuning.
Power-dependent series over a wide range could trace characteristic Mollow
triplet spectra with large Rabi splittings of GHz. In
particular, the effect of dephasing in terms of systematic spectral broadening
of the Mollow sidebands is observed as a strong fingerprint
of excitation-induced dephasing. Our results are in excellent agreement with
predictions of a recently presented model on phonon-dressed QD Mollow triplet
emission in the cavity-QED regime
- …