TY - INPR A1 - Henkel, Carsten A1 - Pieplow, Gregor T1 - Reply to Comment on 'Fully covariant radiation force on a polarizable particle' T2 - New journal of physics : the open-access journal for physics N2 - We argue that the theories of Volokitin and Persson (2014 New J. Phys. 16 118001), Dedkov and Kyasov (2008 J. Phys.: Condens. Matter 20 354006), and Pieplow and Henkel (2013 New J. Phys. 15 023027) agree on the electromagnetic force on a small, polarizable particle that is moving parallel to a planar, macroscopic body, as far as the contribution of evanescent waves is concerned. The apparent differences are discussed in detail and explained by choices of units and integral transformations. We point out in particular the role of the Lorentz contraction in the procedure used by Volokitin and Persson, where a macroscopic body is 'diluted' to obtain the force on a small particle. Differences that appear in the contribution of propagating photons are briefly mentioned. KW - applied classical electromagnetism KW - fluctuation phenomena KW - random processes KW - noise KW - Brownian motion KW - mechanical effects of light Y1 - 2014 U6 - https://doi.org/10.1088/1367-2630/16/11/118002 SN - 1367-2630 VL - 16 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Folman, R. A1 - Krüger, P. A1 - Schmiedmayer, Jörg A1 - Denschlag, J. H. A1 - Henkel, Carsten T1 - Microscopic atom optics : from wires to an atom chip N2 - We review the 10 year long journey into the miniaturization and integration of matter wave optics resulting in devices mounted on surfaces, so called atom chips. The first experiments started with the guiding of atoms with free standing wires and investigated the trapping potentials in simple geometries. Atom optical elements can now be micro fabricated down to 1 um size on atom chips. The creation of a Bose-Einstein condensate miniaturized in surface traps was recently achieved, and the first attempts to integrate light optics are in progress. In this review, we describe microscopic atom optics elements using current carrying and charged structures. Experiments with free standing structures (atom wires)are reviewed, investigating the basic principles of microscopic atom optics. We then discuss the miniaturization on the atom chip. One of the open central questions is dealt with: what happens with cold atoms close to a warm surface, how fast will they heat up or lose their coherence? The review concludes with an outlook of what we believe the future directions to be, and what can be hoped for. Y1 - 2002 ER - TY - JOUR A1 - Henkel, Carsten A1 - Wallis, H. A1 - Westbrook, N. A1 - Aspect, Alain A1 - Sengstock, K. A1 - Ertmer, W. T1 - Theory of atomic diffraction from evanescent waves N2 - We review recent theoretical models and experiments dealing with the diffraction of neutral atoms by a reflection grating, formed by a standing evanescent wave. We analyze diffraction mechanisms proposed for confront the theory with experiment. Y1 - 1999 ER - TY - JOUR A1 - Rogobete, Lavinia A1 - Schniepp, H. A1 - Sandoghdar, Vahid A1 - Henkel, Carsten T1 - Spontaneous emission in nanoscopic dielectric particles Y1 - 2003 SN - 0030-3992 ER - TY - THES A1 - Henkel, Carsten T1 - Coherence theory of atomic de Broglie waves and electromagnetic near fields N2 - Die Arbeit untersucht theoretisch die Wechselwirkung neutraler Teilchen (Atome, Moleküle) mit Oberflächen, soweit sie durch das elektromagnetische Feld vermittelt wird. Spektrale Energiedichten und Kohärenzfunktionen werden hergeleitet und liefern eine umfassende Charakterisierung des Felds auf der sub-Wellenlängen-Skala. Die Ergebnisse finden auf zwei Teilgebieten Anwendung: in der integrierten Atomoptik, wo ultrakalte Atome an thermische Oberflächen koppeln, und in der Nahfeldoptik, wo eine Auflösung unterhalb der Beugungsbegrenzung mit einzelnen Molekülen als Sonden und Detektoren erzielt werden kann. N2 - We theoretically discuss the interaction of neutral particles (atoms, molecules) with surfaces in the regime where it is mediated by the electromagnetic field. A thorough characterization of the field at sub-wavelength distances is worked out, including energy density spectra and coherence functions. The results are applied to typical situations in integrated atom optics, where ultracold atoms are coupled to a thermal surface, and to single molecule probes in near field optics, where sub-wavelength resolution can be achieved. KW - Kohärenztheorie KW - Quantenoptik KW - Quanten-Elektrodynamik (QED) KW - Atomoptik KW - Atomchip KW - Spektroskopie KW - Oberfläche KW - coherence theory KW - quantum optics KW - quantum electrodynamics (QED) KW - atom optics KW - atom chip KW - spectroscopy KW - surface Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-0001272 ER - TY - GEN A1 - Henkel, Carsten A1 - Steane, Andrew M. A1 - Kaiser, Robin A1 - Dalibard, Jean T1 - A modulated mirror for atomic interferometry N2 - A novel atomic beam splitter, using reflection of atoms off an evanescent light wave, is investigated theoretically. The intensity or frequency of the light is modulated in order to create sidebands on the reflected de Broglie wave. The weights and phases of the various sidevands are calculated using three different approaches: the Born approximation, a semiclassical path integral approach, and a numerical solution of the time-dependent Schrdinger equation. We show how this modulated mirror could be used to build practical atomic interferometers. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 102 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-42279 ER - TY - GEN A1 - Henkel, Carsten A1 - Courtois, Jean-Yves A1 - Aspect, Alain T1 - Atomic diffraction by a thin phase grating N2 - We present a semiclassical perturbation method for the description of atomic diffraction by a weakly modulated potential. It proceeds in a way similar to the treatment of light diffraction by a thin phase grating, and consists in calculating the atomic wavefunction by means of action integrals along the classical trajectories of the atoms in the absence of the modulated part of the potential. The capabilities and the validity condition of the method are illustrated on the well-known case of atomic diffraction by a Gaussian standing wave. We prove that in this situation the perturbation method is equivalent to the Raman-Nath approximation, and we point out that the usually-considered Raman-Nath validity condition can lead to inaccuracies in the evaluation of the phases of the diffraction amplitudes. The method is also applied to the case of an evanescent wave reflection grating, and an analytical expression for the diffraction pattern at any incidence angle is obtained for the first time. Finally, the application of the method to other situations is briefly discussed. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 101 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-42269 ER - TY - JOUR A1 - Puhlmann, Dirk A1 - Henkel, Carsten A1 - Heuer, Axel A1 - Pieplow, Gregor A1 - Menzel, Ralf T1 - Characterization of a remote optical element with bi-photons JF - Physica scripta : an international journal for experimental and theoretical physics N2 - We present a simple setup that exploits the interference of entangled photon pairs. 'Signal' photons are sent through a Mach–Zehnder-like interferometer, while 'idlers' are detected in a variable polarization state. Two-photon interference (in coincidence detection) is observed with very high contrast and for significant time delays between signal and idler detection events. This is explained by quantum erasure of the polarization tag and a delayed choice protocol involving a non-local virtual polarizer. The phase of the two-photon fringes is scanned by varying the path length in the signal beam or by rotating a birefringent crystal in the idler beam. We exploit this to characterize one beam splitter of the signal photon interferometer (reflection and transmission amplitudes including losses), using only information about coincidences and control parameters in the idler path. This is possible because our bi-photon state saturates the Greenberger–Yelin–Englert inequality between contrast and predictability. KW - quantum optics KW - quantum eraser KW - entanglement KW - bi-photons Y1 - 2016 U6 - https://doi.org/10.1088/0031-8949/91/2/023006 SN - 0031-8949 SN - 1402-4896 VL - 91 SP - 113 EP - 114 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Hannemann, Mandy A1 - Wegner, Gino A1 - Henkel, Carsten T1 - No-slip boundary conditions for electron hydrodynamics and the thermal Casimir pressure JF - Universe : open access journal N2 - We derive modified reflection coefficients for electromagnetic waves in the THz and far infrared range. The idea is based on hydrodynamic boundary conditions for metallic conduction electrons. The temperature-dependent part of the Casimir pressure between metal plates is evaluated. The results should shed light on the "thermal anomaly," where measurements deviate from the standard fluctuation electrodynamics for conducting metals. KW - dispersion force KW - metal optics KW - Drude model KW - hydrodynamic model KW - spatial KW - dispersion KW - viscosity KW - non-contact heat transfer Y1 - 2021 U6 - https://doi.org/10.3390/universe7040108 SN - 2218-1997 VL - 7 IS - 4 PB - MDPI CY - Basel ER - TY - JOUR A1 - Dikovsky, Valery A1 - Sokolovsky, Vladimir A1 - Zhang, Bin A1 - Henkel, Carsten A1 - Folman, Ron T1 - Superconducting atom chips : advantages and challenges N2 - Superconductors are considered in view of applications to atom chip devices. The main features of magnetic traps based on superconducting wires in the Meissner and mixed states are discussed. The former state may mainly be interesting for improved atom optics, while in the latter, cold atoms may provide a probe of superconductor phenomena. The properties of a magnetic side guide based on a single superconducting strip wire placed in an external magnetic field are calculated analytically and numerically. In the mixed state of type II superconductors, inhomogeneous trapped magnetic flux, relaxation processes and noise caused by vortex motion are posing specific challenges for atom trapping. Y1 - 2009 UR - http://www.springerlink.com/content/101161 U6 - https://doi.org/10.1140/epjd/e2008-00261-5 SN - 1434-6060 ER - TY - GEN A1 - Henkel, Carsten A1 - Courtois, Jean-Yves A1 - Kaiser, Robin A1 - Westbrook, C. A1 - Aspect, Alain T1 - Phase shifts of atomic de Broglie waves at an evanescent wave mirror N2 - A detailed theoretical investigation of the reflection of an atomic de Broglie wave at an evanescent wave mirror is presented. The classical and the semiclassical descriptions of the reflection process are reviewed, and a full wave-mechanical approach based on the analytical soution of the corresponding Schrödinger equation is presented. The phase shift at reflection is calculated exactly and interpreted in terms of instantaneous reflection of the atom at an effective mirror. Besides the semiclassical regime of reflection describable by the WKB method, a pure quantum regime of reflection is identified in the limit where the incident de Broglie wavelength is large compared to the evanescent wave decay length. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 103 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-42289 ER - TY - JOUR A1 - Zurita-Sánchez, Jorge R. A1 - Henkel, Carsten T1 - Lossy electrical transmission lines: Thermal fluctuations and quantization N2 - We present a theoretical framework for the analysis of the statistical properties of thermal fluctuations on a lossy transmission line. A quantization scheme of the electrical signals in the transmission line is formulated. We discuss two applications in detail. Noise spectra at finite temperature for voltage and current are shown to deviate significantly from the Johnson-Nyquist limit, and they depend on the position on the transmission line. We analyze the spontaneous emission, at low temperature, of a Rydberg atom and its resonant enhancement due to vacuum fluctuations in a capacitively coupled transmission line. The theory can also be applied to study the performance of microscale and nanoscale devices, including high-resolution sensors and quantum information processors Y1 - 2006 UR - http://pra.aps.org/pdf/PRA/v73/i6/e063825 U6 - https://doi.org/10.1103/Physreva.73.063825 SN - 1050-2947 ER - TY - JOUR A1 - Henkel, Carsten A1 - Joulain, Karl T1 - Electromagnetic field correlations near a surface with a nonlocal optical response N2 - The coherence length of the thermal electromagnetic field near a planar surface has a minimum value related to the nonlocal dielectric response of the material. We perform two model calculations of the electric energy density and the field's degree of spatial coherence. Above a polar crystal, the lattice constant gives the minimum coherence length. It also gives the upper limit to the near field energy density, cutting off its 1/z(3) divergence. Near an electron plasma described by the semiclassical Lindhard dielectric function, the corresponding length scale is fixed by plasma screening to the Thomas-Fermi length. The electron mean free path, however, sets a larger scale where significant deviations from the local description are visible Y1 - 2006 UR - http://www.springerlink.com/content/100502 U6 - https://doi.org/10.1007/s00340-006-2219-9 SN - 0946-2171 ER - TY - JOUR A1 - Dikovsky, V. A1 - Japha, Y. A1 - Henkel, Carsten A1 - Folman, R. T1 - Reduction of magnetic noise in atom chips by material optimization N2 - We discuss the influence of the material type in metal wires to the electromagnetic fluctuations in magnetic microtraps close to the surface of an atom chip. We show that significant reduction of the magnetic noise can be achieved by replacing the pure noble metal wires with their dilute alloys. The alloy composition provides an additional degree of freedom which enables a, controlled reduction of both magnetic noise and resistivity if the atom chip is cooled. In addition, we provide a careful re-analysis of the magnetically induced trap loss observed by Yu-Ju Lin et al. [Phys. Rev. Lett. 92 050404 (2004)] and find good agreement with an improved theory Y1 - 2005 ER - TY - JOUR A1 - Henkel, Carsten T1 - Nanometer scala electromagnetic field fluctuations accepted for publication Y1 - 2005 SN - 1-588-83042-X ER - TY - JOUR A1 - Henkel, Carsten A1 - Gardiner, Simon A. A1 - Negretti, Antonio T1 - (De)coherence physics with condensates in microtraps N2 - We discuss the dynamics of a condensate in a miniaturized electromagnetic trap formed above a microstructured substrate. Recent experiments have found that trap lifetimes get reduced when approaching the substrate because atoms couple to thermally excited near fields. The data agree quantitatively with our theory [Appl. Phys. B 69, 379 (1999)]. We focus on the decoherence of a quantum degenerate gas in a quasi-one-dimensional trap. Monte Carlo simulations indicate that atom interactions reduce the condensate decoherence rate. This is explained by a simple theory in terms of the suppression of long-wavelength excitations. We present preliminary simulation results for the adiabatic generation of dark solitons Y1 - 2004 SN - 1054-660X ER - TY - JOUR A1 - Zhang, B. A1 - Henkel, Carsten A1 - Haller, E. A1 - Wildermuth, S. A1 - Hofferberth, S. A1 - Kruger, P. A1 - Schmiedmayer, Jörg T1 - Relevance of sub-surface chip layers for the lifetime of magnetically trapped atoms N2 - We investigate the lifetime of magnetically trapped atoms above a planar, layered atom chip structure. Numerical calculations of the thermal magnetic noise spectrum are performed, based on the exact magnetic Green function and multi layer reflection coefficients. We have performed lifetime measurements where the center of a side guide trap is laterally shifted with respect to the current carrying wire using additional bias fields. Comparing the experiment to theory, we find a fair agreement and demonstrate that for a chip whose topmost layer is metallic, the magnetic noise depends essentially on the thickness of that layer, as long as the layers below have a, much smaller conductivity; essentially the same magnetic noise would be obtained with a metallic membrane suspended in vacuum. Based on our theory we give general scaling laws of how to reduce the effect of surface magnetic noise on the trapped atoms Y1 - 2005 ER - TY - JOUR A1 - Kalkbrenner, T. A1 - Hakanson, U. A1 - Schadle, A. A1 - Burger, S. A1 - Henkel, Carsten A1 - Sandoghdar, Vahid T1 - Optical microscopy via spectral modifications of a nanoantenna N2 - The existing optical microscopes form an image by collecting photons emitted from an object. Here we report on the experimental realization of microscopy without the need for direct optical communication with the sample. To achieve this, we have scanned a single gold nanoparticle acting as a nanoantenna in the near field of a sample and have studied the modification of its intrinsic radiative properties by monitoring its plasmon spectrum Y1 - 2005 SN - 0031-9007 ER - TY - JOUR A1 - Henkel, Carsten T1 - Magnetostatic field noise near metallic surfaces N2 - We develop an effective low-frequency theory of the electromagnetic field in equilibrium with thermal objects. The aim is to compute thermal magnetic noise spectra close to metallic microstructures. We focus on the limit where the material response is characterised by the electric conductivity. At the boundary between empty space and metallic microstructures, a large jump occurs in the dielectric function which leads to a partial screening of low-frequency magnetic fields generated by thermal current fluctuations. We resolve a, discrepancy between two approaches used in the past to compute magnetic field noise spectra close to microstructured materials Y1 - 2005 ER - TY - JOUR A1 - Henkel, Carsten A1 - Joulain, Karl T1 - Casimir force between designed materials : what is possible and what not N2 - We establish strict upper limits for the Casimir interaction between multilayered structures of arbitrary dielectric or diamagnetic materials. We discuss the appearance of different power laws due to frequency-dependent material constants. Simple analytical expressions are in good agreement with numerical calculations based on Lifshitz theory. We discuss the improvements required for current ( meta) materials to achieve a repulsive Casimir force Y1 - 2005 SN - 0295-5075 ER -