Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA

Conventional microwave mixers are unsuitable at cryogenic temperatures owing to their large insertion loss and high power dissipation. As quantum computing systems are scaled-up, to reduce cabling overheads in the dilution refrigerators there is an advantage to integrating the classical control electronics on chip at cryogenic temperatures. Here, we describe a fully-superconducting phase and amplitude modulator based on high kinetic inductance transmission lines offering a bias current tuneable impedance. We describe device geometries designed to offer amplitude and phase modulation as well as frequency up-conversion at millikelvin temperatures. Device performance and a route towards ultra-low-loss multiplexing will be discussed. Although designed to scale up control of quantum dot spin qubits, these modulators are expected to be useful for other quantum computing architectures utilizing microwave control.

[1] A. J. Annunziata, D. F. Santavicca et al., Nanotechnology 21, 445202 (2010).

[2] J. Zmuidzinas, Annu. Rev. Condens. Matter Phys. 3, 169 (2012).