PhD Student – Cryo CMOS Circuit Design for Optical Communication in Quantum Computers

In this project, you will address a crucial challenge in quantum computers: how to efficiently transfer a large amount of digital data in and out of a cryogenic refrigerator? The quantum processor will operate in a closed chamber cryogenically refrigerated, thus requiring the transfer of both the input data and the computation results in and out of such a cryogenic chamber over a distance of up to a few meters. While electrical communication via conducting wires seems the straightforward solution, this approach suffers from several limitations, including generating electromagnetic interference and the limited data bandwidth of electrical interconnects. Furthermore, electrical conductors also conduct heat, thus occupying part of the cooling budget of the cryogenic refrigerator. Optical communication presents then a promising alternative thanks to the low thermal conductance of optical fibers and the excellent performance in terms of interference and data rate. Your research will aim to demonstrate the first cryo-CMOS optical transceiver. You will identify the best optical-electrical transducer to operate at cryogenic temperatures and design the cryo-CMOS electric interface to transmit and receive high-speed digital data. Over the course of your PhD, you will design several prototypes of the different cryo-CMOS components of the optical transceiver, tape them out in advanced CMOS technologies, and characterize the resulting prototypes in our advanced cryogenic electrical characterization laboratory. Your results will advance the state-of-the-art in cryo-CMOS circuit design and will result in presentations at top conferences for the advances of integrated circuits and publications in high-impact scientific journals. Your cryo-CMOS optical transceiver will be integrated into the larger prototypes developed at TU Delft and our industrial partners, thus achieving a real impact in the field of quantum technologies.