6,217 research outputs found
Multiparticle Quantum Superposition and Stimulated Entanglement by Parity Selective Amplification of Entangled States
A multiparticle quantum superposition state has been generated by a novel
phase-selective parametric amplifier of an entangled two-photon state. This
realization is expected to open a new field of investigations on the
persistence of the validity of the standard quantum theory for systems of
increasing complexity, in a quasi decoherence-free environment. Because of its
nonlocal structure the new system is expected to play a relevant role in the
modern endeavor on quantum information and in the basic physics of
entanglement.Comment: 13 pages and 3 figure
Continuous variable cloning via network of parametric gates
We propose an experimental scheme for the cloning machine of continuous
quantum variables through a network of parametric amplifiers working as
input-output four-port gates.Comment: 4 pages, 2 figures. To appear on Phys. Rev. Let
Contextual Realization of the Universal Quantum Cloning Machine and of the Universal-NOT gate by Quantum Injected Optical Parametric Amplification
A simultaneous, contextual experimental demonstration of the two processes of
cloning an input qubit and of flipping it into the orthogonal qubit is
reported. The adopted experimental apparatus, a Quantum-Injected Optical
Parametric Amplifier (QIOPA) is transformed simultaneously into a Universal
Optimal Quantum Cloning Machine (UOQCM) and into a Universal NOT
quantum-information gate. The two processes, indeed forbidden in their exact
form for fundamental quantum limitations, will be found to be universal and
optimal, i.e. the measured fidelity of both processes F<1 will be found close
to the limit values evaluated by quantum theory. A contextual theoretical and
experimental investigation of these processes, which may represent the basic
difference between the classical and the quantum worlds, can reveal in a
unifying manner the detailed structure of quantum information. It may also
enlighten the yet little explored interconnections of fundamental axiomatic
properties within the deep structure of quantum mechanics. PACS numbers:
03.67.-a, 03.65.Ta, 03.65.UdComment: 27 pages, 7 figure
Experimental reversion of the optimal quantum cloning and flipping processes
The quantum cloner machine maps an unknown arbitrary input qubit into two
optimal clones and one optimal flipped qubit. By combining linear and
non-linear optical methods we experimentally implement a scheme that, after the
cloning transformation, restores the original input qubit in one of the output
channels, by using local measurements, classical communication and feedforward.
This significant teleportation-like method demonstrates how the information is
preserved during the cloning process. The realization of the reversion process
is expected to find useful applications in the field of modern multi-partite
quantum cryptography.Comment: 10 pages, 3 figure
Anomalous resilient to decoherence macroscopic quantum superpositions generated by universally covariant optimal quantum cloning
We show that the quantum states generated by universal optimal quantum
cloning of a single photon represent an universal set of quantum superpositions
resilient to decoherence. We adopt Bures distance as a tool to investigate the
persistence ofquantum coherence of these quantum states. According to this
analysis, the process of universal cloning realizes a class of quantum
superpositions that exhibits a covariance property in lossy configuration over
the complete set of polarization states in the Bloch sphere.Comment: 8 pages, 6 figure
Preliminary slip rate estimates for the DĂĽzce segment of the North Anatolian Fault Zone from offset geomorphic markers
New estimates on the Quaternary slip rate of the active transform margin of North Anatolia are provided. We investigated the area struck by the 12th November 1999, Mw 7.1 earthquake, that ruptured the Düzce fault segment of the North Anatolian Fault. In order to analyze the spectacular tectonically driven cumulative landforms and the drainage pattern settings, we carried out a 1:25,000-scale geological and geomorphological mapping along the fault trace. We reconstruct and describe, as offset geomorphic markers, right-hand stream deflections and fluvial terraces inset into alluvial fan deposits. Radiocarbon dating indicates that ~100 m stream deflections were built up by the last ~7000 yrs of fault activity. Conversely, two documented and correlated Late Pleistocene fluvial terraces are horizontally offset by ~300 and ~900 m, respectively. These were dated by means of Optically Stimulated Luminescence (OSL) to ~21 ka BP and 60 ka BP. Assuming a constant rate of deformation for the Düzce Fault, ages and related offsets translate to consistent slip-rates that yield an average slip-rate of 15.0 ± 3.2 mm/yr for the last 60 ka. Thus, the Düzce Fault importantly contributes to the North Anatolian margin deformation, suggesting a present-day partitioning of displacement rates with the Mudurnu fault to the south and confirming its important role in the seismic hazard of the area
Enhancing the Violation of the Einstein-Podolsky-Rosen Local Realism by Quantum Hyper-entanglement
Mermin's observation [Phys. Rev. Lett. {\bf 65}, 1838 (1990)] that the
magnitude of the violation of local realism, defined as the ratio between the
quantum prediction and the classical bound, can grow exponentially with the
size of the system is demonstrated using two-photon hyper-entangled states
entangled in polarization and path degrees of freedom, and local measurements
of polarization and path simultaneously.Comment: Minor errors corrected. To appear on Physical Review Letter
LADDER PROOF OF NONLOCALITY WITHOUT INEQUALITIES : THEORETICAL AND EXPERIMENTAL RESULTS
We show how a previous demonstration of nonlocality without inequalities for two spin-half particles can be improved so that a greater proportion of the pairs are shown to be subject to a contradiction with local realism. This is achieved by considering more settings of the apparatus at each end. Also, we report on an experimental realization employing a tunable source of polarization entangled photons. The experimental results violate locality (modulo, the efficiency loophole). {copyright} {ital 1997} {ital The American Physical Society
Combining inland and offshore paleotsunamis evidence: the Augusta Bay (eastern Sicily, Italy) case study
Offshore and inland geological evidence for
multiple tsunami inundations was found in the Augusta Bay
area: (1) the main local historical tsunamis (1908, 1693,
1169), (2) two far-generated tsunamis (i.e. Crete 365AD
and Santorini, 3600 BP), and (3) seven unknown tsunamis).
Average tsunami recurrence intervals from inland and
offshore investigations of about 550 and 320 yr, respectively
were obtained for the past 4 ka. The history of paleotsunamis
from the marine record appears to be as complete as
the historical one for the past millennium, yielding an
average tsunami recurrence interval of 250 yr for the Augusta
Bay. Geological data allow also estimating a minimum
tsunami inundation distance of 530m and a minimum
run-up of 5 m. The marine record contains evidence for
more paleotsunamis with respect to the inland one because
of continuous sedimentation and better preservation of
stratigraphy in the offshore with respect to coastal areas,
which are commonly affected by intermittent-erosion and
sedimentation and anthropic activities.
This work shows that the integration of geological and
historical data can provide critical information regarding
the extent and age of tsunamis of the past (e.g. inundation
distance, age, and frequency), which is of immediate
relevance for tsunami hazard assessment
"All-versus-nothing" nonlocality test of quantum mechanics by two-photon hyperentanglement
We report the experimental realization and the characterization of
polarization and momentum hyperentangled two photon states, generated by a new
parametric source of correlated photon pairs. By adoption of these states an
"all versus nothing" test of quantum mechanics was performed. The two photon
hyperentangled states are expected to find at an increasing rate a widespread
application in state engineering and quantum information. PACS: 03.65.Ud,
03.67.Mn, 42.65. LmComment: Replaced with published versio
- …