End of August we organized a seminar for our group in the mountains of Austria. For a week we stayed in the Ravensburger Hut at almost 2000-meter altitude located close to Langen am Arlberg. We started our trip in Paderborn and in two days we travelled by public transport to Lech am Arlberg. From there it was a three hour walk up to the hut. Even though the weather was not always nice on that day, everyone enjoyed the challenge and the experience…
In our new publication we show the operation of a superconducting single photon detector via a photodiode. Superconducting single photon detectors have become the goldstandard for single photon detection in recent years since they can achieve detection efficiencies of above 95% and show negligible dark noise. These features are vital to realise quantum photonic communication. These superconducting single photon detectors must be operated at…
We just now posted an extended video about the cryogenic SPDC experiment from Nina Amelie Lange. The extended video can be found here, it was edited by Jessika Bruns. The original news article can be found here and the publication here.
We congratulate Jens Großmann who has successfully completed his bachelor thesis titled "Characterising time-resolved homodyne detection with superconducting detectors ".
We congratulate Janik Kramer who has successfully completed his bachelor thesis titled "Characterising a degenerate spontaneous parametric down-conversion source under cryogenic conditions".
In our publication we compare different multiplexing architectures of single-photon detectors. We use the purity of the measurement outcomes to characterize their photon-number-resolving ability. Additionally, we calculate the amount of information the measurement outcomes of the different devices can extract from a Hilbert space with a certain dimension. We could confirm that detectors with more multiplexing outcomes enable a higher…
In our new publication we show the operation of lithium niobate modulators at cryogenic temperatures. We have previously shown the operation of a polarisation converter at 1K. To show the full capabilities of lithium niobate modulators at cryogenic temperature we characterised a phase modulator, directional coupler, and a polarisation converter. These modulators were characterised in respect to their modulation voltage and wavelength dependence…
Six members of the MQO group went to the Conference on Lasers and Electro-Optics (CLEO) from May 15th-20th, 2022 in San Jose. We presented five contributions:
Jan Philipp Höpker - Two-Mode Photon-Number Correlations Created by Measurement-Induced Nonlinearity (Poster) Frederik Thiele - Cryogenic Optical Biasing of a Superconducting Nanowire Single Photon Detector With a Photodiode (Talk) Maximilian Protte - Direct Laser Lithography:…
The week before the Conference on Lasers and Electro-Optics (CLEO) two members of the MQO group (Jan Philipp Höpker and Maximilian Protte) visited the National Institute of Standards and Technology (NIST) in Boulder, Colorado, USA. They were shown their laboratories and had great discussions about superconducting detector technology.
Jun.-Prof. Dr. Tim Bartley, physicist at Paderborn University receives a "ERC Starting Grant" from the European Research Council. The highly endowed "Starting Grant" supports particularly promising scientists who are at the beginning of an independent research career.
The project „Quantum Engineering Superconducting Array Detectors in Low-Light Applications" (QuESADILLA) will focus on developing efficient single-photon detectors for tasks in…
In our paper, we demonstrate the fabrication of micron-wide superconducting nanowire single-photon detectors with a direct laser lithography. This patterning method offers a fast and rapid prototyping of devices and can be used for all types of integrated components in lithium niobate. We were able to show a saturated internal detection efficiency for detectors with an unfolded length of up to 4 mm showing the potential for patterning large areas…
We congratulate Felix Dreher who has successfully completed his master thesis titled "Overcoming pyroelectric damage to integrated superconducting detectors on lithium niobate waveguides".
We congratulate Jan Philipp Höpker who successfully defended his PhD thesis titled "Integrated measurement-induced nonlinearity with superconducting detectors" and was awarded the "Dr. rer. nat." degree by the Faculty of Science at Paderborn University.
In our paper, we demonstrate the coldest spontaneous parametric down-conversion (SPDC) experiment that was done so far. We show that SPDC in nonlinear waveguides, which is typically performed under ambient conditions, remains functional when it is operated at about 4 K. We investigate the source performance metrics and the spectral properties of our SPDC source. Our results indicate that cryogenics principally affect the modes which the SPDC…
