Low-energy single-electron detection using a large-area superconducting micro-strip*

Superconducting strip single-photon detectors (SSPDs) are excellent tools not only for single-photon detection but also for single-particle detection due to their high detection efficiency, low dark counts, and low time jitter. Although the detection of a variety of particles, including electrons with keV-scale energy, has been reported so far, there have been no studies for the detection of low-energy electrons. Also, it has not been clarified how low-energy electrons interact with electrons and/or phonons in a superconductor during the detection of electrons. Here we report the detection property of a superconducting micro-strip single-electron detector (SSED) for electrons with energies below 152 eV. We show that the minimum detectable energy of electrons is about 15 eV with our SSED, which is much lower than those of ions, implying that electron-electron interaction plays a significant role. We also estimate the detection efficiency as at least 45 % when electrons impinging on the stripline possess the energy of 152 eV. SSEDs might open a wide range of applications ranging from condensed matter physics to quantum information science because of their compatibility with the cryogenic environment.