Speaker
Description
The supercurrent quantization due to synchronization of the Bloch oscillations with microwaves in a small Josephson junction was recently demonstrated [1]. The current step is equal to 2efn, where 2e is Cooper pair charge, f is microwave frequency, and n is the integer. The effect is dual to the voltage quantization with step (h/2e)fn, the Shapiro steps, where (h/2e) is the superconducting flux quantum.
We use this phenomenon to develop a new quantum electronic device, the Bloch Transistor (BT). Its functionality is to deliver accurate current to the quantum circuit. One can vary the BT current by four controls: the bias and gate voltages, the frequency and amplitude of the microwave. The gate control of BT is promoted by the Aharonov-Casher effect [2]. The Bloch Transistor consists of two Josephson Junctions (JJ) connected in series, with small island between them. The Josephson junctions operate in a regime of the coherent quantum phase slip. This is provided by the choice of parameters of Josephson Junctions and the environment protection circuit, consisting of compact super-inductors and normal resistors. The flux tunnelling rate across the two junctions depends on the total charge of the island which is capacitively coupled to the gate electrode. The charge of the island controlled by the gate electrode potential.
References
2. Shaikhaidarov et al, Nature Comm., 15, 9326 (2024).
3. Y. Aharonov and A. Casher, Phys. Rev. Lett. 53, 319 (1984).