Entanglement of two interacting bosons in a two dimensional isotropic harmonic trap

We compute the pair entanglement between two interacting bosons in a two dimensional (2D)isotropic harmonic trap. The interaction potential is modeled by a 2D regularized pseudo-potential. By analytically decomposing the wave function into the single particle basis, we show the dependency of the pair entanglement on the scattering length. Our results turn out to be in good agreements with earlier results using a quasi-2D geometry.Comment: 5 figure

Исследование датчиков рН и удельной электрической проводимости фирмы WTW в системе автоматизированного контроля качества очистки сточных вод

We demonstrate the suitability of microcavities based on circular grating resonators (CGRs) as fast switches. This type of optical resonator is characterized by a high quality factor and very small mode volume. The waveguide-coupled CGRs are fabricated with silicon-on-insulator technology compatible with standard complementary metal-oxide semiconductor (CMOS) processing. The linear optical properties of the CGRs are investigated by transmission spectroscopy. From 3D finite-difference time-domain simulations of isolated CGRs, we identify the measured resonances. We probe the spatial distribution and the parasitic losses of a resonant optical mode with scanning near-field optical microscopy. We observe fast all-optical switching within a few picoseconds by optically generating free charge carriers within the cavity. (C) 2009 Optical Society of Americ

Observation of broadband optical gain in quasi-2D CdSe nanoplatelets

Solution processable nanomaterials for photonic applications, in particular light emission and lasing, have received much attention in the past decade(s). A demonstration of ultralow continuous wave optical gain and lasing using CdSe platelets, quasi-2D materials in a colloidal dispersion, was the most recent milestone in this field. Until now, the optical gain in these quasi-2D systems was though to originate from the biexciton-to-exciton transition, much as is the case for 0D colloidal QDs. The net gain should therefore occur at biexciton carrier densties and moreover only develop in a narrow region below the lowest energy exciton feature. Here, we show that quasi-2D colloidal CdSe platelets are instead able to deliver broadband optical gain and that this gain is caused by the formation of a high temperature, unbound electron-hole gas, a first demonstration for a solution processable material. Moreover, the control over the plasma temperature indicates that the material gain can be tuned and even enhanced in different spectral regions. These results shed a new light on the role of excitons in solution processable inorganic gain media and pave the way for the development of more efficient gain media

Technisch-wissenschaftliche Begleitforschung zu den Vorhaben 'Nadelfraesen' einschliesslich der Ermittlung der Verfahrenskenngroessen Abschlussbericht. Abschlussdatum: August 1980

Technische Informationsbibliothek Hannover: RN 7543 (81-005) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Beruehrungslose Abstands- und Geschwindigkeitsmessung

Technische Informationsbibliothek Hannover: AC 5898 +MF / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Measurement of quantum states of neutrons in the Earth's gravitational field

The lowest stationary quantum state of neutrons in the Earth's gravitational field is identified in the measurement of neutron transmission between a horizontal mirror on the bottom and an absorber on top. Such an assembly is not transparent for neutrons if the absorber height is smaller than the "height" of the lowest quantum state

Bright Triplet Emission from Lead Halide Perovskite Nanocrystals

The emission of fully inorganic cesium lead halide (CsPbX3, where X = I,Br,Cl) perovskite-type nanocrystals is tunable over a wide energy range with ultrahigh photoluminescence quantum yields of up to 90%[1] and exhibits narrow emission lines. Due to their facile solution processability and their potential for high-efficiency photovoltaics and light sources they have gained enormous interest. Experiments on single perovskite quantum dots reveal a unique energetic level structure with a lowest bright triplet state[2], thus enabling photon emission rates ~20 and ~1000 times higher compared to any other conventional semiconductor nanocrystals at room and cryogenic temperatures, respectively. We investigate the nature of this exceptionally fast photon emission by temperature dependent quantum yield measurements. Furthermore we discriminate it from composition dependent “A-type” blinking behaviour in intensity-decay time correlation measurements and demonstrate stable, narrowband emission, with suppressed blinking and small spectral diffusion[3] for single CsPbBr2Cl nanocrystals. By means of polarization dependent high resolution spectroscopy, the complex nature of the exciton fine structure splitting and charged exciton emission has been characterized. Based on these measurements, supported by effective-mass models and group theory calculations, we conclude that the triplet exciton state is responsible for the extraordinary photon emission properties of lead halide perovskites. Our results can assist to identify other semiconductors that exhibit bright triplet excitons, with potential implications for improved optoelectronic devices