Noise Thermometry with Two Weakly Coupled Bose-Einstein Condensates

Here we report on the experimental investigation of thermally induced fluctuations of the relative phase between two Bose-Einstein condensates which are coupled via tunneling. The experimental control over the coupling strength and the temperature of the thermal background allows for the quantitative analysis of the phase fluctuations. Furthermore, we demonstrate the application of these measurements for thermometry in a regime where standard methods fail. With this we confirm that the heat capacity of an ideal Bose gas deviates from that of a classical gas as predicted by the third law of thermodynamics.Comment: 4 pages, 4 figure

Hochauflösende Mikroskopie mit Fotoschaltbaren Organischen Farbstoffen

Die Auflösung konventioneller Mikroskope ist begrenzt durch das Abbesche Beugungslimit. Die Auflösungsgrenze lässt sich jedoch fundamental brechen durch sequenzielles Schalten von Markierungsstoffen in der zu betrachtenden Probe zwischen einem detektierbaren An-Zustand und einem nicht detektierbaren Aus-Zustand. Dies kann zum Beispiel durch Fotoschalten geschehen, d.h. durch Einstrahlen von Licht geeigneter Wellenlänge. Die beiden derzeitigen Methoden, die das Schalten der Farbstoffe in dieser Form ausnutzen sind einerseits die RESOLFT-Mikroskopie (REversibleSaturableOpticaL Fluorescence Transitions) und die SMS-Mikroskopie (Single Marker Switching). In der vorliegenden Arbeit werden für beide Methoden neue Ansätze des Fotoschaltens von organischen Farbstoffen untersucht und die Ergebnisse dieser neuen Varianten der hochauflösenden Mikroskopie vorgestellt

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der Georg-August-Universität zu Göttinge

Rhodamine spiroamides for multicolor single-molecule switching fluorescent nanoscopy

The design, synthesis, and evaluation of new rhodamine spiroamides are described. These molecules have applications in optical nanoscopy based on random switching of the fluorescent single molecules. The new markers may be used in (co)localization studies of various objects and their (mutual) positions and shape can be determined with a precision of a few tens of nanometers. Multicolor staining, good photoactivation, a large number of emitted photons, and selective chemical binding with amino or thiol groups were achieved due to the presence of various functional groups on the rhodamine spiroamides. Rigidized sulfonated xanthene fragment fused with six-membered rings, N,N′-bis(2,2,2-trifluoroethyl) groups, and a combination of additional double bonds and sulfonic acid groups with simple aliphatic spiroamide residue provide multicolor properties and improve performance of the rhodamine spiroamides in photoactivation and bioconjugation reactions. Having both essential parts of the photoswitchable assembly - the switching and the fluorescent (reporter) groups - combined in one chemical entity make this approach attractive for further development. A series of rhodamine spiroamides is presented along with characterizations of their most relevant properties for application as fluorescent probes in single-molecule switching and localization microscopy. Optical images with resolutions on the nanometer scale illustrate the potential of the labels in the colocalization of biological objects and the two-photon activation technique with optical sectioning.Fil: Belov, Vladimir N.. Max Planck Institute for Biophysical Chemistry; AlemaniaFil: Bossi, Mariano Luis. Max Planck Institute for Biophysical Chemistry; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fölling, Jonas. Max Planck Institute for Biophysical Chemistry; AlemaniaFil: Boyarskiy, Vadim P.. Max Planck Institute for Biophysical Chemistry; Alemania. St. Petersburg State University; RusiaFil: Hell, Stefan W.. Max Planck Institute for Biophysical Chemistry; Alemani

Imaging nanometer-sized α-synuclein aggregates by superresolution fluorescence localization microscopy

The morphological features of alpha-synuclein (AS) amyloid aggregation in vitro and in cells were elucidated at the nanoscale by far-field subdiffraction fluorescence localization microscopy. Labeling AS with rhodamine spiroamide probes allowed us to image AS fibrillar structures by fluorescence stochastic nanoscopy with an enhanced resolution at least 10-fold higher than that achieved with conventional, diffraction-limited techniques. The implementation of dual-color detection, combined with atomic force microscopy, revealed the propagation of individual fibrils in vitro. In cells, labeled protein appeared as amyloid aggregates of spheroidal morphology and subdiffraction sizes compatible with in vitro supramolecular intermediates perceived independently by atomic force microscopy and cryo-electron tomography. We estimated the number of monomeric protein units present in these minute structures. This approach is ideally suited for the investigation of the molecular mechanisms of amyloid formation both in vitro and in the cellular milieu.Fil: Roberti, Maria Julia. Max Planck Institute For Biophysical Chemistry (karl Friedrich Bonhoeffer Institute); . Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Fölling, Jonas. Institut Max Planck Fuer Gesellschaft; AlemaniaFil: Celej, Maria Soledad. Institut Max Planck Fuer Gesellschaft; AlemaniaFil: Bossi, Mariano Luis. Institut Max Planck Fuer Gesellschaft; AlemaniaFil: Jovin, Thomas M.. Institut Max Planck Fuer Gesellschaft; AlemaniaFil: Jares, Elizabeth Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentin

Fluorescence nanoscopy by ground-state depletion and single-molecule return.

We introduce far-field fluorescence nanoscopy with ordinary fluorophores based on switching the majority of them to a metastable dark state, such as the triplet, and calculating the position of those left or those that spontaneously returned to the ground state. Continuous widefield illumination by a single laser and a continuously operating camera yielded dual-color images of rhodamine- and fluorescent protein-labeled (living) samples, proving a simple yet powerful super-resolution approach

Multicolor Fluorescence Nanoscopy in Fixed and Living Cells by Exciting Conventional Fluorophores with a Single Wavelength

Current far-field fluorescence nanoscopes provide subdiffraction resolution by exploiting a mechanism of fluorescence inhibition. This mechanism is implemented such that features closer than the diffraction limit emit separately when simultaneously exposed to excitation light. A basic mechanism for such transient fluorescence inhibition is the depletion of the fluorophore ground state by transferring it (via a triplet) in a dark state, a mechanism which is workable in most standard dyes. Here we show that microscopy based on ground state depletion followed by individual molecule return (GSDIM) can effectively provide multicolor diffraction-unlimited resolution imaging of immunolabeled fixed and SNAP-tag labeled living cells. Implemented with standard labeling techniques, GSDIM is demonstrated to separate up to four different conventional fluorophores using just two detection channels and a single laser line. The method can be expanded to even more colors by choosing optimized dichroic mirrors and selecting marker molecules with negligible inhomogeneous emission broadening