First CASP EFRC Seminar
Superconducting Devices for Detection of Single Photons
Dr. Sae Woo Nam
National Institute of Standards and Technology (NIST), Boulder, CO
Wednesday, February 10, 10am
Chemistry Division Auditorium, TA-46, Bld. 535, Rm. 103
Abstract
There is increasing interest in using superconducting optical
photon detectors in a variety of applications. These applications
require detectors that have extremely low dark count rates, high count
rates, and high quantum efficiency. I will describe our work on two
types of superconducting detectors, the Superconducting Nanowire Single
Photon Detector (SNSPD) and superconducting Transition-Edge Sensor (TES).
An SSPD is an ultra-thin, ultra-narrow (nm scale) superconducting meander
that is current biased just below its critical current density. When one
or more photon is absorbed, a hot spot is formed that causes the
superconductor to develop a resistance and consequently a voltage pulse.
By exploiting the sharp superconducting-to-normal resistive transtion of
tungsten at 100mK, TES detectors give an output signal that is
proportional to the cumulative energy in an absorption event. This
proportional pulse-height enables the determination of the energy absorbed
by the TES and the direct conversion of sensor pulse-height into photon
number. I will discuss our progress towards developing detectors with
quantum efficiencies approaching 100% as well as describe several
experiments and applications that are enhanced by using these detectors.
