We introduce Cryogenic Optical Localization in 3D (COLD), a method to localize multiple fluorescent sites within a single small protein with Angstrom resolution. We demonstrate COLD by determining the conformational state of the cytosolic Per-ARNT-Sim domain from the histidine kinase CitA of Geobacillus thermodenitnficans and resolving the four biotin sites of streptavidin. COLD provides quantitative 3D information about small- to medium-sized biomolecules on the Angstrom scale and complements other techniques in structural biology.
Coherent Coupling of a Single Molecule to a Scanning Fabry-Perot
Microcavity
Daqing Wang,
Hrishikesh Kelkar,
Diego-Martin Cano,
Tobias Utikal,
Stephan Goetzinger,
Vahid Sandoghdar
Organic dye molecules have been used in a great number of scientific and technological applications, but their wider use in quantum optics has been hampered by transitions to short-lived vibrational levels, which limit their coherence properties. To remedy this, one can take advantage of optical resonators. Here, we present the first results on coherent molecule-resonator coupling, where a single polycyclic aromatic hydrocarbon molecule extinguishes 38% of the light entering a microcavity at liquid helium temperature. We also demonstrate fourfold improvement of single-molecule stimulated emission compared to free-space focusing and take first steps for coherent mechanical manipulation of the molecular transition. Our approach of coupling molecules to an open and tunable microcavity with a very low mode volume and moderately low quality factors of the order of 10(3) paves the way for the realization of nonlinear and collective quantum optical effects.
Strong plasmonic enhancement of biexciton emission: controlled coupling of a single quantum dot to a gold nanocone antenna
Korenobu Matsuzaki,
Simon Vassant,
Hsuan-Wei Liu,
Anke Dutschke,
Bjoern Hoffmann,
Xuewen Chen,
Silke Christiansen,
Matthew R. Buck,
Jennifer A. Hollingsworth,
Stephan Goetzinger,
Vahid Sandoghdar
Multiexcitonic transitions and emission of several photons per excitation comprise a very attractive feature of semiconductor quantum dots for optoelectronics applications. However, these higher-order radiative processes are usually quenched in colloidal quantum dots by Auger and other nonradiative decay channels. To increase the multiexcitonic quantum efficiency, several groups have explored plasmonic enhancement, so far with moderate results. By controlled positioning of individual quantum dots in the near field of gold nanocone antennas, we enhance the radiative decay rates of monoexcitons and biexcitons by 109 and 100 folds at quantum efficiencies of 60 and 70%, respectively, in very good agreement with the outcome of numerical calculations. We discuss the implications of our work for future fundamental and applied research in nano-optics.
Theory of metasurface based perfect absorbers
Rasoul Alaee,
Mohammad Albooyeh,
Carsten Rockstuhl
Based on an analytic approach, we present a theoretical review on the absorption, scattering, and extinction of both dipole scatterers and regular arrays composed of such scatterers i.e. metasurfaces. Besides offering a tutorial by outlining the maximum absorption limit for electrically/magnetically resonant dipole particles/metasurfaces, we give an educative analytical approach to their analysis. Moreover, we put forward the analysis of two known alternatives in providing perfect absorbers out of electrically and or magnetically resonant metasurfaces; one is based on the simultaneous presence of both electric and magnetic responses in so called Huygens metasurfaces while the other is established upon the presence of a back reflector in so called Salisbury absorbers. Our work is supported by several numerical examples to clarify the discussions in each stage.
Phase-Insensitive Scattering of Terahertz Radiation
Mihail Petev,
Niclas Westerberg,
Eleonora Rubino,
Daniel Moss,
Arnaud Couairon,
Francois Legare,
Roberto Morandotti,
Daniele Faccio,
Matteo Clerici
The nonlinear interaction between Near-Infrared (NIR) and Terahertz pulses is principally investigated as a means for the detection of radiation in the hardly accessible THz spectral region. Most studies have targeted second-order nonlinear processes, given their higher efficiencies, and only a limited number have addressed third-order nonlinear interactions, mainly investigating four-wave mixing in air for broadband THz detection. We have studied the nonlinear interaction between THz and NIR pulses in solid-state media (specifically diamond), and we show how the former can be frequency-shifted up to UV frequencies by the scattering from the nonlinear polarisation induced by the latter. Such UV emission differs from the well-known electric field-induced second harmonic (EFISH) one, as it is generated via a phase-insensitive scattering, rather than a sum- or difference-frequency four-wave-mixing process.
A single molecule as a high-fidelity photon gun for producing
intensity-squeezed light
Xiao-Liu Chu,
Stephan Goetzinger,
Vahid Sandoghdar
A two-level atom cannot emit more than one photon at a time. As early as the 1980s, this quantum feature was identified as a gateway to 'single-photon sources', where a regular excitation sequence would create a stream of light particles with photon number fluctuations below the shot noise(1). Such an intensity-squeezed beam of light would be desirable for a range of applications, such as quantum imaging, sensing, enhanced precision measurements and information processing(2,3). However, experimental realizations of these sources have been hindered by large losses caused by low photon-collection efficiencies and photophysical shortcomings. By using a planar metallodielectric antenna applied to an organic molecule, we demonstrate the most regular stream of single photons reported to date. The measured intensity fluctuations were limited by our detection efficiency and amounted to 2.2 dB squeezing.
Core-Shell Plasmonic Nanohelices
Dolfine Kosters,
Anouk de Hoogh,
Hans Zeijlemaker,
Hakki Acar,
Nir Rotenberg,
L. Kuipers
We introduce core-shell plasmonic nanohelices, highly tunable structures that have a different response in the visible for circularly polarized light of opposite handedness. The glass core of the helices is fabricated using electron beam induced deposition and the pure gold shell is subsequently sputter coated. Optical measurements allow us to explore the chiral nature of the nanohelices, where differences in the response to circularly polarized light of opposite handedness result in a dissymmetry factor of 0.86, more than twice of what has been previously reported. Both experiments and subsequent numerical simulations demonstrate the extreme tunability of the core-shell structures, where nanometer changes to the geometry can lead to drastic changes of the optical responses. This tunability, combined with the large differential transmission, make core-shell plasmonic nanohelices a powerful nanophotonic tool for, for example, (bio)sensing applications.
Levitated Plasmonic Nanoantennas in an Aqueous Environment
Yazgan Tuna,
Ji Tae Kim,
Hsuan-Wei Liu,
Vahid Sandoghdar
We report on the manipulation of a plasmonic nanoantenna in an aqueous solution using an electrostatic trap created between a glass nanopipette and a substrate. By scanning a trapped gold nanosphere in the near field of a single colloidal quantum dot embedded under the substrate surface, we demonstrate about 8-fold fluorescence enhancement over a lateral full width at half maximum of about 45 nm. We analyze our results with the predictions of numerical electromagnetic simulations under consideration of the electrostatic free energy in the trap. Our approach could find applications in a number of experiments, where plasmonic effects are employed at liquid solid interfaces.
Chip-Based All-Optical Control of Single Molecules Coherently Coupled to a Nanoguide
Pierre Tuerschmann,
Nir Rotenberg,
Jan Renger,
Irina Harder,
Olga Lohse,
Tobias Utikal,
Stephan Goetzinger,
Vahid Sandoghdar
The feasibility of many proposals in nano quantum-optics depends on the efficient coupling of photons to individual quantum emitters, the possibility to control this interaction on demand, and the scalability of the experimental platform. To address these issues, we report on chip-based systems made of one-dimensional subwavelength dielectric waveguides (nanoguides) and polycyclic aromatic hydrocarbon molecules. We discuss the design and fabrication requirements, present data on extinction spectroscopy of single molecules coupled to a nanoguide mode, and show how an external optical beam can switch the propagation of light via a nonlinear optical process. The presented architecture paves the way for the investigation of many-body phenomena and polaritonic states and can be readily extended to more complex geometries for the realization of quantum integrated photonic circuits.
Small slot waveguide rings for on-chip quantum optical circuits
Nir Rotenberg,
Pierre Tuerschmann,
Harald R. Haakh,
Diego-Martin Cano,
Stephan Goetzinger,
Vahid Sandoghdar
Nanophotonic interfaces between single emitters and light promise to enable new quantum optical technologies. Here, we use a combination of finite element simulations and analytic quantum theory to investigate the interaction of various quantum emitters with slot-waveguide rings. We predict that for rings with radii as small as 1.44 mu m, with a Q-factor of 27,900, near-unity emitter-waveguide coupling efficiencies and emission enhancements on the order of 1300 can be achieved. By tuning the ring geometry or introducing losses, we show that realistic emitter-ring systems can be made to be either weakly or strongly coupled, so that we can observe Rabi oscillations in the decay dynamics even for micron-sized rings. Moreover, we demonstrate that slot waveguide rings can be used to directionally couple emission, again with near-unity efficiency. Our results pave the way for integrated solid-state quantum circuits involving various emitters. (C) 2017 Optical Society of America
Production of Isolated Giant Unilamellar Vesicles under High Salt
Concentrations
Hannah Stein,
Susann Spindler,
Navid Bonakdar,
Chun Wang,
Vahid Sandoghdar
The cell membrane forms a dynamic and complex barrier between the living cell and its environment. However, its in vivo studies are difficult because it consists of a high variety of lipids and proteins and is continuously reorganized by the cell. Therefore, membrane model systems with precisely controlled composition are used to investigate fundamental interactions of membrane components under well-defined conditions. Giant unilamellar vesicles (GUVs) offer a powerful model system for the cell membrane, but many previous studies have been performed in unphysiologically low ionic strength solutions which might lead to altered membrane properties, protein stability and lipid-protein interaction. In the present work, we give an overview of the existing methods for GUV production and present our efforts on forming single, free floating vesicles up to several tens of mu m in diameter and at high yield in various buffer solutions with physiological ionic strength and pH.
Temporal and spectral properties of quantum light
B. Stiller,
U. Seyfarth,
G. Leuchs,
C. Fabre,
V. Sandoghdar,
N. Treps,
L.F. Cugliandolo
Quantum Optics and Nanophotonics
169-227
(2017)
| Journal
| PDF
A Single-Emitter Gain Medium for Bright Coherent Radiation from a Plasmonic Nanoresonator
Pu Zhang,
Igor Protsenko,
Vahid Sandoghdar,
Xue-Wen Chen
We propose and demonstrate theoretically bright coherent radiation from a plasmonic nanoresonator powered by a single three-level quantum emitter. By introducing a dual-pump scheme in a Raman configuration for the three-level system, we overcome the fast decay of nanoplasmons and achieve macroscopic accumulation of nanoplasmons on the plasmonic nanoresonator for stimulated emission. We utilize the optical antenna effect for efficient radiation of the nanoplasmons and predict photon emission rates of 100 THz with up to 10 ps duration pulses and GHz repetition rates with the consideration of possible heating issue. We show that the ultrafast nature of the nanoscopic coherent source allows for operation with solid-state emitters at room temperature in the presence of fast dephasing. We provide physical interpretations of the results and discuss their realization and implications for ultracompact integration of optoelectronics.
Optical alignment of oval graphene flakes
E. Mobini,
A. Rahimzadegan,
R. Alaee,
C. Rockstuhl
Patterned graphene, as an atomically thin layer, supports localized surface plasmon polaritons at mid-infrared or far-infrared frequencies. This provides a pronounced optical force/torque in addition to large optical cross sections and will make it an ideal candidate for optical manipulation. Here, we study the optical force and torque exerted by a linearly polarized plane wave on circular and oval graphene flakes (single layers of graphene). While the torque vanishes for circular flakes, the finite torque allows rotating and orienting oval flakes relative to the electric field polarization. Depending on the wavelength, the alignment is either parallel or perpendicular to the electric field vector. In our contribution, we rely on a full-wave numerical simulation and also on an analytical model that treats the graphene flakes in a dipole approximation. The presented results reveal a good level of control on the spatial alignment of graphene flakes subjected to far-infrared illumination. (C) 2017 Optical Society of America
Experimental demonstration of a predictable single photon source with
variable photon flux
Aigar Vaigu,
Geiland Porrovecchio,
Xiao-Liu Chu,
Sarah Lindner,
Marek Smid,
Albert Manninen,
Christoph Becher,
Vahid Sandoghdar,
Stephan Gotzinger,
Erkki Ikonen
We present a predictable single-photon source (SPS) based on a silicon vacancy centre in nanodiamond which is optically excited by a pulsed laser. At an excitation rate of 70 MHz the source delivers a photon flux large enough to be measured by a low optical flux detector (LOFD). The directly measured photon flux constitutes an absolute reference. By changing the repetition rate of the pulsed laser, we are able to change the photon flux of our SPS in a controllable way which in turn can act as a reference. The advantage of our method is that it does not require precise knowledge of the source efficiency, but the source is calibrated by the LOFD and can be used for detector responsivity characterizations at the few-photon level.
Fluorescence intermittency originates from reclustering in
two-dimensional organic semiconductors
Anthony Ruth,
Michitoshi Hayashi,
Peter Zapol,
Jixin Si,
Matthew P. McDonald,
Yurii V. Morozov,
Masaru Kuno,
Boldizsar Janko
Fluorescence intermittency or blinking is observed in nearly all nanoscale fluorophores. It is characterized by universal power-law distributions in on- and off-times as well as 1/f behaviour in corresponding emission power spectral densities. Blinking, previously seen in confined zero- and one-dimensional systems has recently been documented in two-dimensional reduced graphene oxide. Here we show that unexpected blinking during graphene oxide-to-reduced graphene oxide photoreduction is attributed, in large part, to the redistribution of carbon sp(2) domains. This reclustering generates fluctuations in the number/size of emissive graphenic nanoclusters wherein multiscale modelling captures essential experimental aspects of reduced graphene oxide's absorption/emission trajectories, while simultaneously connecting them to the underlying photochemistry responsible for graphene oxide's reduction. These simulations thus establish causality between currently unexplained, long timescale emission intermittency in a quantum mechanical fluorophore and identifiable chemical reactions that ultimately lead to switching between on and off states.
Experimental realization of an absolute single-photon source based on a
single nitrogen vacancy center in a nanodiamond
Beatrice Rodiek,
Marco Lopez,
Helmuth Hofer,
Geiland Porrovecchio,
Marek Smid,
Xiao-Liu Chu,
Stephan Gotzinger,
Vahid Sandoghdar,
Sarah Lindner,
Christoph Becher,
Stefan Kuck
We report on the experimental realization of an absolute single-photon source based on a single nitrogen vacancy (NV) center in a nanodiamond at room temperature and on the calculation of its absolute spectral photon flux from experimental data. The single-photon source was calibrated with respect to its photon flux and its spectral photon rate density. The photon flux was measured with a low-noise silicon photodiode traceable to the primary standard for optical flux, taking into account the absolute spectral power distribution using a calibrated spectroradiometer. The optical radiant flux is adjustable from 55 fW, which is almost the lowest detection limit for the silicon photodiode, and 75 fW, which is the saturation power of the NV center. These fluxes correspond to total photon flux rates between 190,000 photons per second and 260,000 photons per second, respectively. The single-photon emission purity is indicated by a g((2))(0) value, which is between 0.10 and 0.23, depending on the excitation power. To our knowledge, this is the first single-photon source absolutely calibrated with respect to its absolute optical radiant flux and spectral power distribution, traceable to the corresponding national standards via an unbroken traceability chain. The prospects for its application, e.g., for the detection efficiency calibration of single-photon detectors as well as for use as a standard photon source in the low photon flux regime, are promising. (C) 2017 Optical Society of America
Fundamental limits of optical force and torque
A. Rahimzadegan,
Rasoul Alaee Khanghah,
I. Fernandez-Corbaton,
C. Rockstuhl
Optical force and torque provide unprecedented control on the spatial motion of small particles. A valid scientific question, that has many practical implications, concerns the existence of fundamental upper bounds for the achievable force and torque exerted by a plane wave illumination with a given intensity. Here, while studying isotropic particles, we show that different light-matter interaction channels contribute to the exerted force and torque, and analytically derive upper bounds for each of the contributions. Specific examples for particles that achieve those upper bounds are provided. We study how and to which extent different contributions can add up to result in the maximum optical force and torque. Our insights are important for applications ranging from molecular sorting, particle manipulation, and nanorobotics up to ambitious projects such as laser-propelled spaceships.
Contact
Nano-Optics Division Prof. Vahid Sandoghdar
Max Planck Institute for the Science of Light Staudtstr. 2 91058 Erlangen, Germany
