Komiyama S, Astafiev O, Antonov V, Kutsuwa T, Hirai H
Department of Basic Science, University of Tokyo, Japan.
Nature. 2000 Jan 27;403(6768):405-7. doi: 10.1038/35000166.
The far-infrared region (wavelengths in the range 10 microm-1 mm) is one of the richest areas of spectroscopic research, encompassing the rotational spectra of molecules and vibrational spectra of solids, liquids and gases. But studies in this spectral region are hampered by the absence of sensitive detectors--despite recent efforts to improve superconducting bolometers, attainable sensitivities are currently far below the level of single-photon detection. This is in marked contrast to the visible and near-infrared regions (wavelengths shorter than about 1.5 microm), in which single-photon counting is possible using photomultiplier tubes. Here we report the detection of single far-infrared photons in the wavelength range 175-210 microm (6.0-7.1 meV), using a single-electron transistor consisting of a semiconductor quantum dot in high magnetic field. We detect, with a time resolution of a millisecond, an incident flux of 0.1 photons per second on an effective detector area of 0.1 mm2--a sensitivity that exceeds previously reported values by a factor of more than 10(4). The sensitivity is a consequence of the unconventional detection mechanism, in which one absorbed photon leads to a current of 10(6)-10(12) electrons through the quantum dot. By contrast, mechanisms of conventional detectors or photon assisted tunnelling in single-electron transistors produce only a few electrons per incident photon.
远红外区域（波长范围在10微米至1毫米之间）是光谱研究最丰富的领域之一，涵盖了分子的转动光谱以及固体、液体和气体的振动光谱。但是，该光谱区域的研究因缺乏灵敏探测器而受到阻碍——尽管最近人们努力改进超导测辐射热计，但目前可达到的灵敏度仍远低于单光子探测水平。这与可见光和近红外区域（波长小于约1.5微米）形成鲜明对比，在可见光和近红外区域，使用光电倍增管可以进行单光子计数。在此，我们报告了利用置于强磁场中的半导体量子点构成的单电子晶体管，检测到波长范围在175 - 210微米（6.0 - 7.1毫电子伏特）的单远红外光子。我们以毫秒级的时间分辨率，在0.1平方毫米的有效探测器面积上检测到每秒0.1个光子的入射通量——该灵敏度比之前报道的值高出10^4倍以上。这种灵敏度源于非常规的探测机制，即一个被吸收的光子会使10^6 - 10^12个电子通过量子点形成电流。相比之下，传统探测器的机制或单电子晶体管中的光子辅助隧穿，每个入射光子仅产生少数几个电子。
