Detection of single FIR-photon absorption using quantum dots

Abstract

We demonstrate single-photon detection in a range of sub-millimeter waves (λ=0.17–0.20mm) by using lateral semiconductor quantum dots fabricated on a two-dimensional high-mobility GaAs/AlGaAs single heterostructure crystal. When a sub-millimeter photon is absorbed by a quantum dot upon cyclotron resonance, an excited electron–hole pair induces a strong polarization within the dot. This intra-dot polarization switches on (or off) the conductance resonance when the dot is operated as a single-electron transistor. The lifetime of this polarized state of the quantum dot is extremely long, reaching as long a value as 20 min. This enables us to detect individual events of single photon absorption as the conductance switching. As a detector, the effective noise equivalent power (NEP) is roughly estimated to reach on the order of 10−22W/Hz1/2, a value superior to the ever reported values of conventional detectors by a factor more than 104.