Charge Detection Towards the Readout of Bistable Charge States in Molecular QCA

Charge sensing plays a crucial role in quantum computing systems, often employing Single Electron Transistors (SETs) as on-chip sense amplifiers to determine the state of a qubit. However, fabrication of SETs may not always be plausible as it involves additional processing steps and demands increased chip area and improved SET yield. In this work, we demonstrate a single-port radio frequency gate reflectometry setup for single charge sensing without SETs. By strategically placing a set of gates around a structure, composed of two nanoscale metal dots separated by a tunnel barrier, we showcase single electron charge transfer and detection within a sub-20nm space. In our approach, a single gate serves as both a charge manipulator and a detector. The change in the complex admittance associated with a single electron tunneling event is detected in the reflected RF signal. Our proposed system holds potential for sensing the charge of topological qubits,