Speaker: Alessandro Paghi
Superconducting circuits based on hybrid InAs Josephson Junctions (JJs) and Josephson Field Effect Transistors (JoFETs) play a starring role in the design of fast and ultra-low power consumption solid-state quantum electronics. Conventionally, 3D substrates, 2D quantum wells (QWs), and 1D nanowires (NWs) made of InAs are employed to create superconducting circuits with hybrid JJs and JoFETs. Each platform has its advantages and disadvantages. We recently proposed the InAs-on-insulator (InAsOI), a groundbreaking platform for developing superconducting electronics. An epilayer of semiconducting InAs with different electron densities is grown onto an InAlAs metamorphic buffer, efficiently used as a cryogenic insulator to decouple adjacent devices electrically. JJs with various lengths and widths are fabricated employing Al as a superconductor and InAs with different electron densities, reaching a remarkable switching current density of 7.3 μA μm−1. Then, we manufactured JoFETs featuring high-k dielectrics as a gate insulator able to entirely suppress the switching current and increase the normal-state resistance by 20 times with a gate voltage in the range |0÷5| V. Eventually, triggered by the abilities of InAsOI, we reported the Time Division Multiplexing (TDM) of supercurrent with a 1-input 8-outputs voltage-actuated hybrid superconducting demultiplexer for the first time. The device comprises 14 ON/OFF InAsOI-JoFETs routed with Al traces working at the same time up to 100 MHz at 50 mK, These achievements open up the practical implementation of superconducting TDM as a key to drastically reducing I/O lines, costs, and space occupation in a cryostat, enabling the scalability of superconducting electronics.
[1] A. Paghi, G. Trupiano, G. De Simoni, O. Arif, L. Sorba, and F. Giazotto. InAs on Insulator: A New Platform for Cryogenic Hybrid Superconducting Electronics. Adv. Funct. Mater. 2024, 2416957.
[2] S. Battisti, G. De Simoni, A. Braggio, A. Paghi, L. Sorba, and F. Giazotto. Extremely Weak Sub-Kelvin Electron-Phonon Coupling in InAs on Insulator. Appl. Phys. Lett. 125, 202601 (2024).
[3] A. Paghi, L. Borgongino, S. Tortorella, G. De Simoni, E. Strambini, L . Sorba, and F. Giazotto. Supercurrent Multiplexing with Solid-State Integrated Hybrid Superconducting Electronics. arXiv (https://arxiv.org/abs/2410.11721).
Seminar realized in the framework of the funded projects:
-H2020-EU.1.2.- EXCELLENT SCIENCE - Future and Emerging Technologies (FET) under grant 964398 (SuperGate)
-HORIZON.3.1 - The European Innovation Council (EIC) – Transition Open programme under grant 101057977 (SPECTRUM)
-Piano Nazionale di Ripresa e Resilienza, Ministero dell’Università e della Ricerca (PNRR MUR) Project under Grant PE0000023-NQSTI.
Host: Fabio Taddei