Time-Reversed EPR and the Choice of Histories in Quantum Mechanics

When a single photon is split by a beam splitter, its two `halves' can entangle two distant atoms into an EPR pair. We discuss a time-reversed analogue of this experiment where two distant sources cooperate so as to emit a single photon. The two `half photons,' having interacted with two atoms, can entangle these atoms into an EPR pair once they are detected as a single photon. Entanglement occurs by creating indistinguishabilility between the two mutually exclusive histories of the photon. This indistinguishabilility can be created either at the end of the two histories (by `erasing' the single photon's path) or at their beginning (by `erasing' the two atoms' positions).Comment: 6 pages, 5 figures. Presented at the Solvay Conference in Physics, November 2001, Delphi, Greece. To be published in Quantum Computers and Computing, 2002 and in the Proceedings of XXII Solvay Conference in Physics. New York: World Scientific, 200

Functional Glyconanomaterials

Nanotechnology provides a new array of techniques and platforms to study biological processes including glycosystems [...

Pressure ulcers: understanding the challenges of promoting quality

Pressure ulcers affect quality of life and general wellbeing, and create significant difficulties for patients, their carers and families. Pressure ulcers are associated with morbidity and mortality, and prove costly for healthcare providers. This article identifies the Government’s quality agenda and the importance of maintaining, developing and delivering quality care for the prevention of pressure ulceration

Comparison of subsampling strategies for UAV-mounted subsurface radar imaging systems

This paper compares two subsampling strategies for UAV-mounted subsurface radar imaging systems, which feature non-uniform acquisitions that have an impact on the quality of the resulting radar image. The first method is based on selecting those samples that meet four conditions related to the UAV flight speed and stability. In contrast, the second relies on dividing the observation domain in a grid of cells, and selecting only a maximum of a given number of samples within each cell. The impact of both techniques on the image quality is assessed by means of measurements.Principado de Asturias / FICYT under grant “Ayudas para grupos de investigación de organismos del Principado de Asturias durante el período 2021-2023”, reference AYUD/2021/51706, and by the Ministry of Science and Innovation of Spain under projects MILLIHAND (RTI2018-095825-B-I00) and META-IMAGER (PID2021-122697OB-I00), and by the Ministry of Universities of Spain and European Union (NextGenerationEU) under projects MU-21-UP2021-030-53519863 and MU-21-UP2021-030-71667225.2022 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meetin

Safe Exploration for Optimization with Gaussian Processes

We consider sequential decision problems under uncertainty, where we seek to optimize an unknown function from noisy samples. This requires balancing exploration (learning about the objective) and exploitation (localizing the maximum), a problem well-studied in the multi-armed bandit literature. In many applications, however, we require that the sampled function values exceed some prespecified "safety" threshold, a requirement that existing algorithms fail to meet. Examples include medical applications where patient comfort must be guaranteed, recommender systems aiming to avoid user dissatisfaction, and robotic control, where one seeks to avoid controls causing physical harm to the platform. We tackle this novel, yet rich, set of problems under the assumption that the unknown function satisfies regularity conditions expressed via a Gaussian process prior. We develop an efficient algorithm called SafeOpt, and theoretically guarantee its convergence to a natural notion of optimum reachable under safety constraints. We evaluate SafeOpt on synthetic data, as well as two real applications: movie recommendation, and therapeutic spinal cord stimulation