Quality of a Which-Way Detector

We introduce a measure Q of the "quality" of a quantum which-way detector, which characterizes its intrinsic ability to extract which-way information in an asymmetric two-way interferometer. The "quality" Q allows one to separate the contribution to the distinguishability of the ways arising from the quantum properties of the detector from the contribution stemming from a-priori which-way knowledge available to the experimenter, which can be quantified by a predictability parameter P. We provide an inequality relating these two sources of which-way information to the value of the fringe visibility displayed by the interferometer. We show that this inequality is an expression of duality, allowing one to trace the loss of coherence to the two reservoirs of which-way information represented by Q and P. Finally, we illustrate the formalism with the use of a quantum logic gate: the Symmetric Quanton-Detecton System (SQDS). The SQDS can be regarded as two qubits trying to acquire which way information about each other. The SQDS will provide an illustrating example of the reciprocal effects induced by duality between system and which-way detector.Comment: 10 pages, 5 figure

Detector for Particle Surface Contamination

A system and method for detecting and quantizing particle fallout contamination particles which are collected on a transparent disk or other surface employs an optical detector, such as a CCD camera, to obtain images of the disk and a computer for analyzing the images. From the images, the computer detects, counts and sizes particles collected on the disk The computer also determines, through comparison to previously analyzed images, the particle fallout rate, and generates an alarm or other indication if the rate exceeds a maximum allowable value. The detector and disk are disposed in a housing having an aperture formed therein for defining the area on the surface of the disk which is exposed to the particle fallout. A light source is provided for evenly illuminating the disk. A first drive motor slowly rotates the disk to increase the amount of its surface area which is exposed through the aperture to the particle fallout. A second motor is also provided for incrementally scanning the disk in a radial direction back and forth over the camera so that the camera eventually obtains images of the entire surface of the disk which is exposed to the particle fallout

Measuring a photonic qubit without destroying it

Measuring the polarisation of a single photon typically results in its destruction. We propose, demonstrate, and completely characterise a \emph{quantum non-demolition} (QND) scheme for realising such a measurement non-destructively. This scheme uses only linear optics and photo-detection of ancillary modes to induce a strong non-linearity at the single photon level, non-deterministically. We vary this QND measurement continuously into the weak regime, and use it to perform a non-destructive test of complementarity in quantum mechanics. Our scheme realises the most advanced general measurement of a qubit: it is non-destructive, can be made in any basis, and with arbitrary strength.Comment: 4 pages, 3 figure

Cold atoms in videotape micro-traps

We describe an array of microscopic atom traps formed by a pattern of magnetisation on a piece of videotape. We describe the way in which cold atoms are loaded into one of these micro-traps and how the trapped atom cloud is used to explore the properties of the trap. Evaporative cooling in the micro-trap down to a temperature of 1 microkelvin allows us to probe the smoothness of the trapping potential and reveals some inhomogeneity produced by the magnetic film. We discuss future prospects for atom chips based on microscopic permanent-magnet structures.Comment: Submitted for EPJD topical issue "Atom chips: manipulating atoms and molecules with microfabricated structures

Versorgung und Reanimation des reifen Neugeborenen nach der Geburt : Basierend auf der aktuellen Leitlinie des European Resuscitation Council 2021

Zusammenfassung Die volle Reanimation eines Neugeborenen mit Beatmungen, Thoraxkompressionen und der Gabe von Medikamenten ist ein äußerst seltenes Ereignis, das selbst neonatologische Teams immer wieder vor Herausforderungen stellt. Gerade in diesen seltenen und häufig dramatischen Situationen ist schnelles und umsichtiges Handeln im Team gefragt. Dabei ist die effektivste und meist einzig notwendige Maßnahme für die erfolgreiche Versorgung eines nicht spontan atmenden Neugeborenen eine suffiziente Maskenbeatmung. Wird diese effektiv durchgeführt, sind beim Neugeborenen in den seltensten Fällen tatsächlich Thoraxkompressionen notwendig. Im März 2021 wurde vom European Resuscitation Council (ERC) die neue Leitlinie zur Reanimation von Neugeborenen publiziert. Auf Basis dieser Leitlinie beschreibt der vorliegende Beitrag detailliert den im Algorithmus der Versorgung und Reanimation von reifen Neugeborenen dargestellten Handlungsablauf. Er richtet sich damit einerseits insbesondere an NichtneonatologInnen, die für die Versorgung v. a. von reifen Neugeborenen nach der Geburt verantwortlich sind. Andererseits soll er auch jenen zur Unterstützung dienen, die medizinisches Personal in der Versorgung von lebensbedrohten Neugeborenen trainieren und den Algorithmus der Neugeborenenreanimation als didaktisches Konzept vermitteln. Abstract The resuscitation of a neonate with the need for ventilation, chest compressions and the administration of drugs is an extremely rare event that repeatedly challenges even neonatal teams. It is precisely in these rare and often dramatic situations that rapid and prudent team action is required. The most effective and usually the only necessary measure for the successful resuscitation of a neonate who is not breathing spontaneously is sufficient mask ventilation. If ventilation is performed effectively, chest compressions are rarely necessary in the neonate. In March 2021, the European Resuscitation Council (ERC) published the new guidelines for neonatal resuscitation. Based on these guidelines, this article describes in detail the course of action outlined in the algorithm for the stabilisation and resuscitation of term neonates. On the one hand, it is aimed at non-neonatologists who are responsible for the care of term neonates after birth. On the other hand, it is also intended to support those who train medical personnel in the care of life-threatened neonates and teach the algorithm of neonatal resuscitation as a didactic concept

Invasive species

Globally, about 2,000 marine non-indige¬nous species (NIS) have been introduced to new locations through human-mediated movements. A few of those have econom¬ic value, but most have had negative eco¬logical, socioeconomic or human health impacts. With increased trade and climate change, biological invasions are likely to increase

Guiding neutral atoms around curves with lithographically patterned current-carrying wires

Laser-cooled neutral atoms from a low-velocity atomic source are guided via a magnetic field generated between two parallel wires on a glass substrate. The atoms bend around three curves, each with a 15-cm radius of curvature, while traveling along a 10-cm-long track. A maximum flux of 2*10^6 atoms/sec is achieved with a current density of 3*10^4 A/cm^2 in the 100x100-micrometer-cross-section wires. The kinetic energy of the guided atoms in one transverse dimension is measured to be 42 microKelvin.Comment: 9 page

A Minimal Length from the Cutoff Modes in Asymptotically Safe Quantum Gravity

Within asymptotically safe Quantum Einstein Gravity (QEG), the quantum 4-sphere is discussed as a specific example of a fractal spacetime manifold. The relation between the infrared cutoff built into the effective average action and the corresponding coarse graining scale is investigated. Analyzing the properties of the pertinent cutoff modes, the possibility that QEG generates a minimal length scale dynamically is explored. While there exists no minimal proper length, the QEG sphere appears to be "fuzzy" in the sense that there is a minimal angular separation below which two points cannot be resolved by the cutoff modes.Comment: 26 pages, 1 figur

Simulated Annealing for Topological Solitons

The search for solutions of field theories allowing for topological solitons requires that we find the field configuration with the lowest energy in a given sector of topological charge. The standard approach is based on the numerical solution of the static Euler-Lagrange differential equation following from the field energy. As an alternative, we propose to use a simulated annealing algorithm to minimize the energy functional directly. We have applied simulated annealing to several nonlinear classical field theories: the sine-Gordon model in one dimension, the baby Skyrme model in two dimensions and the nuclear Skyrme model in three dimensions. We describe in detail the implementation of the simulated annealing algorithm, present our results and get independent confirmation of the studies which have used standard minimization techniques.Comment: 31 pages, LaTeX, better quality pics at http://www.phy.umist.ac.uk/~weidig/Simulated_Annealing/, updated for publicatio

Quantitative wave-particle duality and non-erasing quantum erasure

The notion of wave-particle duality may be quantified by the inequality V^2+K^2 <=1, relating interference fringe visibility V and path knowledge K. With a single-photon interferometer in which polarization is used to label the paths, we have investigated the relation for various situations, including pure, mixed, and partially-mixed input states. A quantum eraser scheme has been realized that recovers interference fringes even when no which-way information is available to erase.Comment: 6 pages, 4 figures. To appear in Phys. Rev.