News
New Publication “A scalable multi-photon coincidence detector based on superconducting nanowires”
Coincidence detection of single photons is crucial in numerous quantum technologies and usually requires multiple time-resolved single-photon detectors. However, the electronic readout becomes a major challenge when the measurement basis scales to large numbers of spatial modes. Here, we address this problem by introducing a two-terminal coincidence detector that enables scalable readout of an array of detector segments based on superconducting nanowire microstrip transmission line. Exploiting timing logic, we demonstrate a sixteen-element detector that resolves all 136 possible single-photon and two-photon coincidence events. We further explore the pulse shapes of the detector output and resolve up to four-photon events in a four-element device, giving the detector photon-number-resolving capability. This new detector architecture and operating scheme will be particularly useful for multi-photon coincidence detection in large-scale photonic integrated circuits.
A complete description of the work may be found here.
Citation:
Di Zhu, Qing-Yuan Zhao, Hyeongrak Choi, Tsung-Ju Lu, Andrew E. Dane, Dirk R. Englund, Karl K. Berggren. “A scalable multi-photon coincidence detector based on superconducting nanowires” Nature Nanotechnology (2018)
New Publication “Exploring proximity effects and large depth of field in helium ion beam lithography: large-area dense patterns and tilted surface exposure”
Helium ion beam lithography (HIL) is an emerging nanofabrication technique. It benefits from a reduced interaction volume compared to that of an electron beam of similar energy, and hence reduced long-range scattering (proximity effect), higher resist sensitivity and potentially higher resolution. Furthermore, the small angular spread of the helium ion beam gives rise to a large depth of field. This should enable patterning on tilted and curved surfaces without the need of any additional adjustments, such as laser-auto focus. So far, most work on HIL has been focused on exploiting the reduced proximity effect to reach single-digit nanometer resolution, and has thus been concentrated on single-pixel exposures over small areas. Here we explore two new areas of application. Firstly, we investigate the proximity effect in large-area exposures and demonstrate HIL’s capabilities in fabricating precise high-density gratings on large planar surfaces (100 μm × 100 μm, with pitch down to 35 nm) using an area dose for exposure. Secondly, we exploit the large depth of field by making the first HIL patterns on tilted surfaces (sample stage tilted 45°). We demonstrate a depth of field greater than 100 μm for a resolution of about 20 nm.
A complete description of the work may be found here.
Citation:
Ranveig Flatabø, Akshay Agarwal, Richard Hobbs, Martin M Greve, Bodil Holst and Karl K Berggren “Exploring proximity effects and large depth of field in helium ion beam lithography: large-area dense patterns and tilted surface exposure” Nanotechnology 29, 27 (2018)
Navid Abedzadeh Highlighted by RLE
Periodically, the Research Laboratory for Electronics (RLE) at MIT highlights one research student. This month, QNN’s Navid Abedzadeh was highlighted. Navid is currently involved in the Quantum Electron Microscope project. The aim of this project is developing a tool that is proposed to be capable of imaging biological samples on a nanometer-scale resolution without damaging them.
Check out the RLE Spotlight here.
Emily Toomey awarded 2017 Ernst A. Guillemin Thesis Award for best EE Master’s Thesis
Congratulations to Emily Toomey for being awarded the 2017 Ernst A. Guillemin Thesis Award for best electrical engineering Master’s Thesis in the Department of Electrical Engineering and Computer Science. Emily’s thesis, titled “Microwave response of nonlinear oscillations in resistively shunted superconducting nanowires” describes her work on studying the control of thermal behavior in superconducting nanowires through resistive shunting. In particular, it investigates how the resulting high-frequency relaxation oscillations interact with an external drive to produce behavior conventionally associated with Josephson junctions.
More information about this award may be found here.
Qing-Yuan Zhao awarded the 2nd prize in the Jan Evetts SuST award at EUCAS
Congratulation to former QNN post-doc Qing-Yuan Zhao for being awarded the 2nd prize in the Jan Evetts SuST award at the EUCAS conference for his paper:
Qing-Yuan Zhao, Adam N. McCaughan, Andrew E. Dane, Karl K. Berggren, Thomas Ortlepp. “A nanoCryotron comparator can connect single-flux quantum circuits to conventional electronics“. Superconducting Science and Technology 30, 044002 (2017)
