The kinetic inductance traveling-wave amplifier: an alternative to high electron mobility transistors

High electron mobility transistors (HEMTs) are widely used in quantum computing as a second amplifier, because of their wideband, high saturation power, and relatively low noise performance. However, they typically require milliwatts of power, which will limit the development of quantum computers, as they scale up to hundreds or thousands of qubits. We propose to use kinetic inductance traveling-wave amplifiers (KITs) at 4K as an alternative to HEMTs. KITs consume three orders of magnitude less power than HEMTs, and have enough power-handling to read thousands of qubits or cryogenic sensors simultaneously, while having enough gain to replace HEMTs in the amplification chain. Furthermore, they have recently been shown to be near-quantum-limited over several gigahertz of bandwidth when operated at mK temperatures [1]. We present the characterization of an amplification chain where a KIT at 4K replaces a HEMT, and in particular will discuss its noise performance as well as its suitability for qubit readout.
[1]: Malnou M. et.al. arXiv: 2007.00638 (2020)