Session 1D

Symposium: “Quantum Technology” organized by Urbasi Sinha and Vibhor Singh

Charge amplification approaching the quantum limit

An in-depth understanding of the electrical properties of mesoscopic systems requires direct insight into various quantum phenomena such as electron-electron correlations, dephasing and decoherence, quantum oscillations, single-electron charging, excitation and de-excitation process. Most of these phenomena are short-time-scaled, fragile and, sensitive to environmental decoherence. Conventional transport studies have limited reach in these studies as it probes only the average behavior of the system whereas, a complete understanding of these phenomena requires temporal and spatial information of individual electrons in the system. Quantum point contact (QPC) and the superconducting single electron transistor (S-SET) based charge amplifiers are exploited for many of these studies. QPC based amplifiers are also considered as the readout devices for solid-state spin qubits. In this talk, an overview of charge sensing techniques using QPC charge amplifiers will be presented. In addition, ongoing works on attaining nanosecond time-scale charge amplification by coupling QPC amplifiers to superconducting planar microwave resonators also will be discussed. I will also discuss noise properties and backaction of these devices on to the measurement system.