109 research outputs found
A quantum delayed choice experiment
Quantum systems exhibit particle-like or wave-like behaviour depending on the
experimental apparatus they are confronted by. This wave-particle duality is at
the heart of quantum mechanics, and is fully captured in Wheeler's famous
delayed choice gedanken experiment. In this variant of the double slit
experiment, the observer chooses to test either the particle or wave nature of
a photon after it has passed through the slits. Here we report on a quantum
delayed choice experiment, based on a quantum controlled beam-splitter, in
which both particle and wave behaviours can be investigated simultaneously. The
genuinely quantum nature of the photon's behaviour is tested via a Bell
inequality, which here replaces the delayed choice of the observer. We observe
strong Bell inequality violations, thus showing that no model in which the
photon knows in advance what type of experiment it will be confronted by, hence
behaving either as a particle or as wave, can account for the experimental
data
Experimental Perfect Quantum State Transfer
The transfer of data is a fundamental task in information systems.
Microprocessors contain dedicated data buses that transmit bits across
different locations and implement sophisticated routing protocols. Transferring
quantum information with high fidelity is a challenging task, due to the
intrinsic fragility of quantum states. We report on the implementation of the
perfect state transfer protocol applied to a photonic qubit entangled with
another qubit at a different location. On a single device we perform three
routing procedures on entangled states with an average fidelity of 97.1%. Our
protocol extends the regular perfect state transfer by maintaining quantum
information encoded in the polarisation state of the photonic qubit. Our
results demonstrate the key principle of perfect state transfer, opening a
route toward data transfer for quantum computing systems
Método para determinação do valor da localização com uso de técnicas inferenciais e geoestatísticas na avaliação em massa de imóveis
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Civil
Atomically-thin quantum dots integrated with lithium niobate photonic chips
The electro-optic, acousto-optic and nonlinear properties of lithium niobate
make it a highly versatile material platform for integrated quantum photonic
circuits. A prerequisite for quantum technology applications is the ability to
efficiently integrate single photon sources, and to guide the generated photons
through ad-hoc circuits. Here we report the integration of quantum dots in
monolayer WSe2 into a Ti in-diffused lithium niobate directional coupler. We
investigate the coupling of individual quantum dots to the waveguide mode,
their spatial overlap, and the overall efficiency of the hybrid-integrated
photonic circuit
Upgrading the Wiener index
The Wiener index W is the oldest molecular-graph-based structure-descriptor. It is defined as the sum of the distances of all pairs of vertices of the molecular graph G, where the distance is the number of edges in the shortest path connecting the respective vertices, and where G is the hydrogen-depleted molecular graph. This seemingly very simple topological index could be "upgraded" (a) by using as the distance the sum of the bond lengths along the shortest path, or (b) by using the Euclidean distance between the respective pairs of atoms. Each of these "upgraded" Wiener indices could be computed either (α) for the hydrogen-depleted or (β) for the hydrogen-filled molecular graph. We provide examples showing that none of the modifications (aα), (aβ), (bα), (bβ) yields better results than the ordinary Wiener index, and that there is a very good linear correlation between W and its "upgraded" variants.Centro de Química Inorgánica (CEQUINOR
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