Gate-based Readout Research Articles

Mixed-mode RF reflectometry of quantum dots for reduction of crosstalk effects

RF reflectometry is a promising technique for spin qubit readout, suitable for large-scale integrated qubit systems by combination with multiplexing techniques and gate-based readout. However, one of the challenges in such systems would be that the accuracy of RF readout of individual qubits can be degraded by crosstalk among dense RF readout lines. In this study, we propose a mixed-mode RF reflectometry to reduce the effect of the crosstalk and verify its effectiveness by electromagnetic field simulations. The results of the simulations show the possibility of suppressing the influence of crosstalk by using mixed modes.

Probing the limits of gate-based charge sensing.

Quantum computation requires a qubit-specific measurement capability to readout the final state of individual qubits. Promising solid-state architectures use external readout electrometers but these can be replaced by a more compact readout element, an in situ gate sensor. Gate-sensing couples the qubit to a resonant circuit via a gate and probes the qubit's radiofrequency polarizability. Here we investigate the ultimate performance of such a resonant readout scheme and the noise sources that limit its operation. We find a charge sensitivity of 37 μe Hz(-1/2), the best value reported for this technique, using the example of a gate sensor strongly coupled to a double quantum dot at the corner states of a silicon nanowire transistor. We discuss the experimental factors limiting gate detection and highlight ways to optimize its sensitivity. In total, resonant gate-based readout has advantages over external electrometers both in terms of reduction of circuit elements as well as absolute charge sensitivity.