Florent LECOCQ (NIST (Boulder))
Qubit measurements using nonreciprocal amplifiers
Résumé :
High-fidelity QND qubit measurements are a cornerstone of quantum error correction schemes. In state-of-the-art superconducting quantum processors, this is achieved by combining dispersive readout with low-noise microwave measurement chains based on parametric amplifiers. However, to protect the qubits from unwanted backaction, typical systems require multiple stages of bulky magnetic circulators, a major roadblock toward scaling this approach to thousands or millions of qubits. Here I will discuss various efforts toward building amplifiers which embed directionality, and their applications to qubit measurements. In particular, I will focus on the experimental demonstration of high-fidelity, multiplexed, QND qubit measurements with a circulator-free readout chain, achieving all the requirements for scalability.
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