Southwest Quantum Information and Technology

Single-shot charge readout using a cryogenic heterojunction-bipolar-transistor preamplifier inline with a silicon single-electron-transistor at millikelvin temperatures

Presenting Author: Matt Curry, University of New Mexico
Contributing Author(s): T. D. England, J. R. Wendt, T. Pluym, M. P. Lilly, S. M. Carr, M. S. Carroll

Single-shot quantum state readout is a requirement for many implementations of quantum information processing. The single-shot readout fidelity is dependent on the signal-to-noise-ratio (SNR) and bandwidth of the readout detection technique. Several different approaches are being pursued to enhance read-out including RF-reflectometry, RF-transmission, parametric amplification, and transistor-based cryogenic preamplification. The transistor-based cryogenic preamplifier is attractive in part because of the reduced experimental complexity compared with the RF techniques. Here we present single-shot charge readout using a cryogenic Heterojunction-Bipolar-Transistor (HBT) inline with a silicon SET charge-sensor at millikelvin temperatures. For the relevant range of HBT DC-biasing, the current gain is 100 to 2000 and the power dissipation is 50 nW to 5 μW, with the microfabricated SET and discrete HBT in an integrated package mounted to the mixing chamber stage of a dilution refrigerator. Using a Random Telegraph Signal (RTS), we experimentally demonstrate a SNR of up to 10 with a bandwidth of 1 MHz, corresponding to a single-shot time-domain charge-sensitivity of approximately 1E-4 e/√Hz. This measured charge-sensitivity is comparable to the values reported using the RF techniques but with minimal overhead in terms of experimental implementation.

(Session 5 : Thursday from 5:00 - 7:00 pm)