Browsing by Author "Chekurov, N."

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  • Aberration-insensitive microscopy using optical field-correlation imaging
    (2019-06-01) Ilina, E.; Nyman, M.; Švagždyte, I.; Chekurov, N.; Kaivola, M.; Setälä, T.; Shevchenko, A.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The possibility to reduce the effect of optical aberrations has been proposed in several publications on classical ghost imaging. The two-armed ghost-imaging systems make use of spatially incoherent illumination and point-by-point scanned intensity-correlation measurements in the arms. In this work, we introduce a novel ghostlike imaging method that uses a Mach-Zehnder interferometer and is based on optical-field interference instead of intensity correlations. The method allows us to obtain sharp images of microscopic objects even in the presence of severe aberrations that completely destroy the intensity-based image. Furthermore, pure phase objects can be imaged with micrometer-scale resolution in the presence of strong aberrations, which has not been demonstrated previously with a correlation-based imaging technique. In the setup, we use a light-emitting diode source and an ordinary camera as the only light detector. The imaging approach that we put forward in this work may find significant applications in advanced optical microscopy, optical coherence tomography, and a variety of interferometric sensors and detectors.
  • Environment-Assisted Tunneling as an Origin of the Dynes Density of States
    (2010) Pekola, Jukka P.; Maisi, V. F.; Kafanov, S.; Chekurov, N.; Kemppinen, A.; Pashkin, Yu. A.; Saira, O.-P.; Möttönen, M.; Tsai, J. S.
     School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We show that the effect of a high-temperature environment in current transport through a normal metal–insulator–superconductor tunnel junction can be described by an effective density of states in the superconductor. In the limit of a resistive low-Ohmic environment, this density of states reduces into the well-known Dynes form. Our theoretical result is supported by experiments in engineered environments. We apply our findings to improve the performance of a single-electron turnstile, a potential candidate for a metrological current source.