Vink, I. T and Nooitgedagt, T. and Schouten, R. N. and Vandersypen, L. M. K. and Wegscheider, Werner
Cryogenic amplifier for fast real-time detection of single-electron tunneling.
Applied Physics Letters 91 (12), p. 123512.
The authors employ a cryogenic high electron mobility transistor (HEMT) amplifier to increase the bandwidth of a charge detection setup with a quantum point contact (QPC) charge sensor. The HEMT is operating at 1 K and the circuit has a bandwidth of 1 MHz. The noise contribution of the HEMT at high frequencies is only a few times higher than that of the QPC shot noise. The authors use this setup to monitor single-electron tunneling to and from an adjacent quantum dot. The authors measure fluctuations in the dot occupation as short as 400 ns, 20 times faster than in previous work.