The Gedankenexperimente of quantum mechanichs become reality: On the 2012 Nobel Prize in Physics, awarded to Serge Haroche and David J. Wineland

El desenvolupament de la mecànica quàntica a principis del segle XX va constituir una de les més grans revolucions tant en les ciències experimentals i en les ciències exactes com en la filosofia, i va modificar completament la manera d'entendre el món tant a nivell microscòpic com macroscòpic. De fet, tal com varen fer notar els seus fundadors, la mecànica quàntica és força contradictòria respecte a la nostra forma clàssica de pensar. Per superar aquesta limitació, Erwin Schrödinger i Albert Einstein, entre d'altres, van proposar una sèrie d'experiments ideals que mostraven el comportament paradoxal de la mecànica quàntica, entre els quals l'anomenat «gat de Schrödinger» i la «paradoxa EPR» (o paradoxa Einstein-Podolsky-Rosen) són els més coneguts. Aquestes propostes experimentals, que es coneixen amb el nom alemany de Gedankenexperimente (experiments mentals), feien ús del principi de superposició i de l'entrellaçament dels sistemes quànticsapper mostrar les estranyes propietats de la mecànica quàntica. Tanmateix, com va indicar el mateix Schrödinger, es tractava de propostes ridícules perquè mai aconseguiríem manipular partícules individuals. El Premi Nobel de Física 2012 ha estat atorgat a Serge Haroche i David J. Wineland, que van ser capaços, mitjançant sofisticats dispositius experimentals, d'atrapar i manipular fotons i ions individuals, respectivament, tot fent realitat els Gedankenexperimente proposats als inicis de la mecànica quàntica. A més, aquells experiments van establir les bases per a un nou camp de recerca, la ciència de la informació quàntica, i per al desenvolupament de noves aplicacions com ara la construcció de rellotges atòmics de precisió anteriorment mai assolida. Aquests desenvolupaments han marcat l'inici de l'anomenada segona revolució quàntica.The development of quantum mechanics at the beginning of the 20th century constituted one of the greatest revolutions in the theoretical and experimental sciences as well as in philosophy, completely transforming the way we understand the world at both micro- and macroscales. In fact, as its founders pointed out, quantum mechanics is strongly counterintuitive to our classical way of thinking. To overcome this limitation, Erwin Schrödinger and Albert Einstein, among others, proposed a series of idealized experiments to illustrate the paradoxical behavior of quantum mechanics, with the best known being “Schrödinger’s cat” and the “EPR paradox” (Einstein-Podolsky-Rosen paradox). These thought experiments, referred to by the German Gedankenexperimente, made use of the superposition principle and the entanglement of quantum systems to show the strange properties of quantum mechanics. However, they were somehow ridiculous proposals since, as indicated by Schrödinger himself, we would never be able to manipulate individual particles. The 2012 Nobel Prize in Physics was awarded to Serge Haroche and David J. Wineland, who, with extremely sophisticated experimental devices, are able to trap and manipulate individual photons and ions, respectively, thus allowing the Gedankenexperimente proposed at the beginning of quantum mechanics to become reality. In addition, these experiments set the foundations for a new field of research, quantum information science, and for the development of new applications, such as atomic clocks with unprecedented accuracy. These developments have signaled the beginning of a second quantum revolution

Development of an SDN control plane for Time-Sensitive Networking (TSN) endpoints

Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructur

Transport of ultracold atoms between concentric traps via spatial adiabatic passage

Spatial adiabatic passage processes for ultracold atoms trapped in tunnel-coupled cylindrically symmetric concentric potentials are investigated. Specifically, we discuss the matter-wave analogue of the rapid adiabatic passage (RAP) technique for a high fidelity and robust loading of a single atom into a harmonic ring potential from a harmonic trap, and for its transport between two concentric rings. We also consider a system of three concentric rings and investigate the transport of a single atom between the innermost and the outermost rings making use of the matter-wave analogue of the stimulated Raman adiabatic passage (STIRAP) technique. We describe the RAP-like and STIRAP-like dynamics by means of a two- and a three-state models, respectively, obtaining good agreement with the numerical simulations of the corresponding two-dimensional Schr\"odinger equation.Comment: 13 pages, 6 figure

Free Space Optical Polarization De-multiplexing and Multiplexing by means of Conical Refraction

Polarization de-multiplexing and multiplexing by means of conical refraction is proposed to increase the channel capacity for free space optical communication applications. The proposed technique is based on the forward-backward optical transform occurring when a light beam propagates consecutively along the optic axes of two identical biaxial crystals with opposite orientations of their conical refraction characteristic vectors. We present experimental proof of usefulness of the conical refraction de-multiplexing and multiplexing technique by increasing in one order of magnitude the channel capacity at optical frequencies in a propagation distance of 4m

Coherent injecting, extracting, and velocity filtering of neutral atoms in a ring trap via spatial adiabatic passage

We introduce here a coherent technique to inject, extract, and velocity filter neutral atoms in a ring trap coupled via tunneling to two additional waveguides. By adiabatically following the transverse spatial dark state, the proposed technique allows for an efficient and robust velocity dependent atomic population transfer between the ring and the input/output waveguides. We have derived explicit conditions for the spatial adiabatic passage that depend on the atomic velocity along the input waveguide as well as on the initial population distribution among the transverse vibrational states. The validity of our proposal has been checked by numerical integration of the corresponding two dimensional Schr\"odinger equation with state-of-the-art parameter values for $^{87}$Rb atoms and an optical dipole ring trap.Comment: To be published in European Physical Journal