Measurement and control of a superconducting quantum processor with a fully integrated radio-frequency system on a chip

• Published in: Review of scientific instruments Vol. 93; no. 10
• Main Authors: Tholén, Mats O., Borgani, Riccardo, Di Carlo, Giuseppe Ruggero, Bengtsson, Andreas, Križan, Christian, Kudra, Marina, Tancredi, Giovanna, Bylander, Jonas, Delsing, Per, Gasparinetti, Simone, Haviland, David B.
• Format: Journal Article
• Language: English
• Published: 01.10.2022
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/5.0101398

We describe a digital microwave platform called Presto, designed for measurement and control of multiple quantum bits (qubits) and based on the third-generation radio-frequency system on a chip. Presto uses direct digital synthesis to create signals up to 9 GHz on 16 synchronous output ports, while synchronously analyzing responses on 16 input ports. Presto has 16 DC-bias outputs, four inputs and four outputs for digital triggers or markers, and two continuous-wave outputs for synthesizing frequencies up to 15 GHz. Scaling to a large number of qubits is enabled through deterministic synchronization of multiple Presto units. A Python application programming interface configures a firmware for synthesis and analysis of pulses, coordinated by an event sequencer. The analysis integrates template matching (matched filtering) and low-latency (184–254 ns) feedback to enable a wide range of multi-qubit experiments. We demonstrate Presto’s capabilities with experiments on a sample consisting of two superconducting qubits connected via a flux-tunable coupler. We show single-shot readout and active reset of a single qubit; randomized benchmarking of single-qubit gates showing 99.972% fidelity, limited by the coherence time of the qubit; and calibration of a two-qubit iSWAP gate.