Single Shot Spin Readout Using A Cryogenic High-Electron-Mobility Transistor Amplifier At Sub-Kelvin Temperatures

We use a cryogenic high-electron-mobility transistor circuit to amplify the current from a single electron transistor, allowing for demonstration of single shot readout of an electron spin on a single P donor in Si with 100 kHz bandwidth and a signal to noise ratio of similar to 9. In order to reduce the impact of cable capacitance, the amplifier is located adjacent to the Si sample, at the mixing chamber stage of a dilution refrigerator. For a current gain of similar to 2.7 x 10(3), the power dissipation of the amplifier is 13 mu W, the bandwidth is similar to 1.3 MHz, and for frequencies above 300 kHz the current noise referred to input is <= 70 fA/root Hz. With this amplification scheme, we are able to observe coherent oscillations of a P donor electron spin in isotopically enriched Si-28 with 96% visibility. (C) 2016 AIP Publishing LLC.