Dynamics of Bloch oscillating transistor near bifurcation threshold

TL;DR

This paper investigates the bifurcation behavior of the Bloch oscillating transistor, demonstrating how tuning the base current and Josephson energy influences bistability and current gain, with implications for device performance near critical thresholds.

Contribution

It reveals how the bifurcation threshold depends on Josephson coupling energy and demonstrates record-high current gains near the bifurcation point.

Findings

Bistability can be controlled by base current tuning.

Record-large current gains achieved near bifurcation.

Bifurcation threshold depends on Josephson energy and tunneling processes.

Abstract

Tendency to bifurcate can often be utilized to improve performance characteristics of amplifiers or even to build detectors. Bloch oscillating transistor is such a device. Here we show that bistable behaviour can be approached by tuning the base current and that the critical value depends on the Josephson coupling energy $E_J$ of the device. We demonstrate record-large current gains for device operation near the bifurcation point at small $E_J$. From our results for the current gains at various $E_J$, we determine the bifurcation threshold on the $E_J$ - base current plane. The bifurcation threshold curve can be understood using the interplay of inter- and intra-band tunneling events.