Double quantum dots as a high sensitive submillimeter-wave detector

A single electron transistor (SET) consisting of parallel double quantum dots fabricated in a GaAs/Al$_{x}$Ga$_{1-x}$As heterostructure crystal is demonstrated to serve as an extremely high sensitive detector of submillimeter waves (SMMW). One of the double dots is ionized by SMMW via Kohn-mode plasma excitation, which affects the SET conductance through the other quantum dot yielding the photoresponse. Noise equivalent power of the detector for wavelengths about 0.6 mm is estimated to reach the order of $10^{-17}$ W/$\sqrt{Hz}$ at 70 mK.Comment: 3 pages, 4 figures, REVTeX, submitted to Appl.Phys.Let

Detection of Single Submillimeter-Wave Photons Using Quantum Dots

Single-photon detection in a range of submillimeter waves (λ = 0.17-0.20 mm) is demonstrated by using lateral semiconductor quantum dots fabricated on a high-mobility GaAs/AlGaAs single heterostructure crystal. When a submillimeter photon is absorbed by the quantum dot while it is operated as a single-electron transistor, it switches on (or off) the conductance through the quantum dot. An incident flux of 0.1 photons/s on an effective detector area, (0.1 mm)$\text{}^{2}$, is detected with a 1 ms time resolution. The effective noise equivalent power is roughly estimated to reach on the order of 10$\text{}^{-22}$ W/Hz$\text{}^{1}\text{}^{/}\text{}^{2}$ , a value superior to the ever reported best values of conventional detectors by a factor more than 10$\text{}^{4}$

Far-infrared spectroscopy of single quantum dots in high magnetic fields

Excitation spectra of single GaAs/AlGaAs quantum dots (QD's) are studied by using a technique of far-infrared single-photon detection. The spectra consist of a single resonance line, the resonance frequency of which is by several percent larger than the cyclotron-resonance frequency but is substantially smaller than the magnetoplasma frequencies of mesa-etched QD's earlier found through the standard far-infrared transmission spectroscopy. The resonance frequency is found to be in substantial agreement with the characteristic frequency of the parabolic bare confinement potential of the QD's, and is ascribed to the excitation of the upper branch of the Kohn-mode collective plasma oscillations

Electrostatics of quantum dots in high magnetic fields and single far-infrared photon detection

Electron transport through a single electron transistor (SET) is studied with and without illumination of far-infrared (FIR) radiation in high magnetic fields. The SET consists of a GaAs/AlGaAs quantum dot (QD). The transport characteristics obtained without the FIR illumination is well analyzed in terms of capacitance matrix by assuming that the QD in strong magnetic fields is split into isolated conductive regions. When a FIR photon is absorbed by a QD upon cyclotron resonance, an excited electron-hole pair induces a charge polarization within the QD, which switches on or off the SET conductance. The absorption of single-FIR photons is thus detected as individual conductance switches of the SET. Experimental results show that the lifetime of the excited state of a QD (with the internal polarization) is longer than the instrumental time constant, 1 ms, in a magnetic field range of B=3.4-4.2 T, in which the lowest orbital Landau levels are completely occupied while the higher Landau level with a small number of electrons is slightly occupied. The wavelength of the FIR-photon detection, being determined by the magnetic field applied to the QD, ranges from 0.2 mm to 0.17 mm

Far-infrared spectroscopy of single quantum dots in high magnetic fields

Excitation spectra of single GaAs/AlGaAs quantum dots (QD's) are studied by using a technique of far-infrared single-photon detection. The spectra consist of a single resonance line, the resonance frequency of which is by several percent larger than the cyclotron-resonance frequency but is substantially smaller than the magnetoplasma frequencies of mesa-etched QD's earlier found through the standard far-infrared transmission spectroscopy. The resonance frequency is found to be in substantial agreement with the characteristic frequency of the parabolic bare confinement potential of the QD's, and is ascribed to the excitation of the upper branch of the Kohn-mode collective plasma oscillations