PASN Detection

Measuring the high frequency electromagnetic power radiated by a quantum conductor in a microwave circuit is challenging. The important mismatch between the quantum conductor impedance (h/e2) and the typical circuit impedance (50 Ω) makes for example the detection of the high frequency shot noise limited to few GHz. To circumvent this limitation, on-chip photon detectors have been developed using a second nearby quantum conductor and exploiting its photon detection ability. Examples are GaAs/AlGaAs 2D electron gas patterned quantum dots and Aluminium or Niobium SIS junctions.
These detectors have shown high sensitivity but need very low temperatures and lack of a universal photon-response. The
photon-response of quantum dots depends on an energy scale set by their geometry, that of superconducting junctions is limited by a characteristic energy gap and both systems show tunnel resistance variability. Regarding bolometric detectors their efficiency depends on the phonon relaxation time, requires low temperature and shows slow response time. We propose here to use the effect of Photon-Assisted Shot Noise (PASN) for on-chip radiation detection.
It is based on the low frequency current noise generated by the partitioning of photon excited electron and holes which are
scattered by the conductor. Remarkably, the resulting PASN noise provides a direct counting of the electron-hole pairs whose number is universally related to the incident radiation power. Up to a Fano factor, characterizing the type of scattering, the PASN response is independent on the nature and geometry of the quantum conductor used for detection. Ordered in temperature/frequency range, from few tens of milli-Kelvin and GHz frequency to several hundreds of Kelvin and THz, a wide range of conductors can be used like Quantum Point Contacts (this work), diffusive metallic or semi-conducting films, Graphene, Carbone nanotubes and other molecular conductors. PASN radiation detector are also expected very fast and only limited by
the electron dwell time in the scattering region of the conductor.

  • Harvesting dissipated energy with a mesoscopic ratchet, B. Roche, P. Roulleau, T. Jullien, Y. Jompol, I. Farrer, D.A. Ritchie and D.C. Glattli, submitted (2013)
  • Detecting noise with shot noise: a new on-chip Photon Detector, Y. Jompol, P. Roulleau, T. Jullien, B. Roche, I. Farrer, D.A. Ritchie and D.C. Glattli, submitted (2013)
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Scanning electron microscope view of the sample. Two lines defined by wet etching of the mesa are coupled via a coupling capacitance CC. On the upper line are patterned two QPCs in series: in red the QPC emitter, and in white a series resistor tuned on a plateau (therefore noiseless). On the lower line, the QPC detector is colored in blue.

Advanced Grant