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

TL;DR

This paper introduces Presto, a fully integrated RF system on a chip for scalable, high-fidelity measurement and control of superconducting qubits, enabling advanced multi-qubit experiments with low-latency feedback.

Contribution

The paper presents Presto, a novel digital microwave platform with integrated RF components, synchronized multi-unit operation, and real-time analysis for superconducting quantum processors.

Findings

Achieved single-shot readout and active reset of a qubit

Demonstrated 99.972% fidelity in single-qubit gates

Calibrated a two-qubit iSWAP gate

Abstract

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 response on 16 input ports. Presto has 16 DC-bias outputs, 4 inputs and 4 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.