QuantAlpsAn ecosystem for quantum science & technologies :
From the philosopher to the industrial

Abstract: Broadband sensing of nanodevices for applications such as high-speed qubit readout is often accomplished using gate radio-frequency reflectometry of quantum dots (QD). The parameter of interest is the (typically very small) change in the (typically very large) impedance of the QD resulting from single-electron charging. Sensitive measurements of such systems are only possible if a properly designed matching network (MN) is used. We propose and demonstrate a simple straightforward method to design and optimize a pi matching network for readouts of devices with large impedance, Z≥1MΩ. It is based on a single low temperature calibrated measurement of an unadjusted network composed of a single L-section followed by a simple calculation to determine a value of the “balancing” capacitor needed to achieve matching conditions for a pi network. We demonstrate that the proposed calibration/error correction technique can be directly applied at low temperature using inexpensive calibration standards.