Network switch for Quantum Computer

The core component of QueSt is an all-metallic superconducting transistor-controlled via gate voltages. This transistor exploits the peculiar characteristics of a superconducting material to work at frequencies (~1 THz) unachievable with classical semiconductor electronic components and with nearly zero power dissipation.

QueSt acts as an interface between the external CMOS electronics and the internal quantum qubits through a chip for IN/OUT communication, without introducing any additional need to modify the rest of the QC architecture and reducing the need for physical cable lines. QueSt directs input signals to the quantum chip and output signals from the quantum chip to the external electronics. QueSt also reduces the number of channels inside the cryostat, by compacting the physical lines onto a solid-state device (Fig. 4). After introducing QueSt in a QC heat typically generated from IN/OUT lines would be eliminated.


The technological breakthrough promised by SPECTRUM refers to at least two classes of innovative features. Owing to the intrinsic adaptability of the network switch QueSt, we plan to implement it in both QC and more conventional TC and high-performance classical computing applications. The expected competitive advantages are respectively:

Quantum technologies:

Low-power dissipation

QueSt is expected to dissipate almost no power (less than 1nW), reducing energy waste and downtime for QC. We envisage a reduction of the downtime after a single switching event from 95% up to 99% of its typical values (~ 10 hours).

Simultaneous control of multiple qubit configurations

this will increase the scalability and flexibility of the QC, allowing multiple measurement configurations with the same amount of control RF lines used nowadays but with reduced footprint and the cost of the wiring by about 75%.

Voltage control

our QueSt switch is based on voltage-driven technology, which makes it perfectly compatible with the existing CMOS, allowing smooth system integration and interoperability.

High switching speed

reduced switching time, i.e. at least one order of magnitude lower compared to a conventional CMOS, to perform ultrafast operations in a quantum processor.

Telecommunications and high-performance computing:

High telecommunication speed

QueSt can potentially work with frequencies up to 1 THz thanks to the usage of niobium-based superconductors, which makes QueSt suitable for the development of future 6G applications.


the operational principle of QueSt makes it totally compatible with the state-of-the-art CMOS technology currently in use. Supporting the existing CMOS infrastructure with QueSt technology will enable boosting the performance of current TC networks.

Low power dissipation

QueSt can reduce the energy needed for the operation of large-scale TCs and High-Performance Computing (HPC) clusters by at least two orders of magnitude thanks to the use of superconductors.