Topic: superconducting circuits

Hamish Johnston interviews Yonatan Cohen, co-founder and chief technology officer of Quantum Machines, about control systems linking quantum computers to classical computation. Topics include the increasing importance of hybrid control as qubit counts grow, support for superconducting circuits, trapped ions, neutral atoms, spins and nitrogen-vacancy centers, industry collaborations and careers in quantum technology.

Michel Devoret explains why a quantum measurement amplifier must transmit a signal without returning its own noise to the system being measured. He relates directional amplification to the breakdown of reciprocity, introducing Faraday rotation and microwave circulators used between superconducting circuits and measurement amplifiers. The lecture then examines the limitations of magnetic circulators: stray magnetic fields are undesirable near superconducting quantum circuits, and bulky components constrain the number of measurement channels inside a dilution refrigerator. Devoret develops a th