Tuning of Two-Stage HEMT Cryogenic Amplifier to Reduce Electron Temperature in a Nearby Quantum Dot

Cryogenic amplification using the two-stage HEMT amplifier [L. A. Tracy, et al., APL 108, 063101 (2016)] is one of several competing techniques for boosting the bandwidth of low-current high-impedance measurements in a dilution refrigerator. While it has previously been shown that the heat dissipation of the amplifier can be tuned below the typical cooling power of a mixing chamber in a dilution refrigerator, we show that the amplifier may still create a local heating effect that could substantially raise the electron temperature in a nearby sample (e.g., a quantum dot qubit). Fortunately the amplifier can be tuned to mitigate heat dissipation while preserving bandwidth. We present evidence that operation of the amplifier can be consistent with quantum dot electron temperatures of ~100 mK and single shot measurement.