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 - Pieplow, Gregor A1 - Henkel, Carsten T1 - Cherenkov friction on a neutral particle moving parallel to a dielectric JF - Journal of physics : Condensed matter N2 - We describe a simple mechanism of quantum friction for a particle moving parallel to a dielectric, based on a fully relativistic framework and the assumption of local equilibrium. The Cherenkov effect explains how the bare ground state becomes globally unstable and how fluctuations of the electromagnetic field and the particle's dipole are converted into pairs of excitations. Modeling the particle as a silver nano-sphere, we investigate the spectrum of the force and its velocity dependence. We find that the damping of the plasmon resonance in the silver particle has a relatively strong impact near the Cherenkov threshold velocity. We also present an expansion of the friction force near the threshold velocity for both damped and undamped particles. KW - quantum friction KW - quantum electrodynamics KW - Cherenkov radiation KW - transition radiation KW - fluctuation forces Y1 - 2015 U6 - https://doi.org/10.1088/0953-8984/27/21/214001 SN - 0953-8984 SN - 1361-648X VL - 27 IS - 21 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Elsner, Robert A1 - Puhlmann, Dirk A1 - Pieplow, Gregor A1 - Heuer, Axel A1 - Menzel, Ralf T1 - Transverse distinguishability of entangled photons with arbitrarily shaped spatial near- and far-field distributions JF - Journal of the Optical Society of America : B, Optical physics N2 - Entangled photons generated by spontaneous parametric downconversion are ubiquitous in quantum optics. In general, they exhibit a complex spatial photon count distribution. This spatial structure is responsible for seemingly surprising results concerning, e.g., complementarity such as the apparent simultaneous observation of interference fringes V and which-way information D at a double slit, as recently reported by Menzel et al. [Proc. Natl. Acad. Sci. USA 109, 9314 (2012)]. We implement a complete quantitative model of the SPDC interaction that fully incorporates the effects of crystal anisotropies, phase matching, and the pump beam structure and allows for arbitrary manipulations of the SPDC light in the near and far fields. This enables us to establish an upper bound D-2 + V-2 <= 1.47 for the experimental parameters reported by Menzel et al. We report new experimental results that agree excellently with these theoretical predictions. The new model enables a detailed quantitative analysis of this surprising result and the fair sampling interpretation of biphotons passing a double slit. (C) 2015 Optical Society of America Y1 - 2015 U6 - https://doi.org/10.1364/JOSAB.32.001910 SN - 0740-3224 SN - 1520-8540 VL - 32 IS - 9 SP - 1910 EP - 1919 PB - Optical Society of America CY - Washington ER - 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 - Pieplow, Gregor A1 - Henkel, Carsten T1 - Fully covariant radiation force on a polarizable particle JF - New journal of physics : the open-access journal for physics N2 - The electromagnetic force on a polarizable particle is calculated in a covariant framework. Local equilibrium temperatures for the electromagnetic field and the particle's dipole moment are assumed, using a relativistic formulation of the fluctuation-dissipation theorem. Two examples illustrate radiative friction forces: a particle moving through a homogeneous radiation background and above a planar interface. Previous results for arbitrary relative velocities are recovered in a compact way. Y1 - 2013 U6 - https://doi.org/10.1088/1367-2630/15/2/023027 SN - 1367-2630 VL - 15 IS - 4 PB - IOP Publ. Ltd. CY - Bristol ER -