Experimental advances with the QICK (Quantum Instrumentation Control Kit) for superconducting quantum hardware

TL;DR

The paper presents experimental advances enabled by the open-source Quantum Instrumentation Control Kit (QICK) running on Gen 3 RFSoC hardware to control superconducting qubits. It demonstrates multiplexed signal generation/readout, mixer-free readout, pre-distorted fast flux pulses, and phase-coherent parametric operations, with a focus on phase coherence and low-latency control. Key results include four-qubit simultaneous readout on a single RFSoC, 145 ps-resolution pre-distorted flux pulses for fast tuning, and a high-fidelity $\\sqrt{b\mathrm{SWAP}}$ gate with long-term phase stability, validated by quantum state tomography and cross-entropy benchmarking. These advances reduce hardware complexity, enable scalable multi-qubit control, and pave the way for multi-board scaling and broader platform applicability, including potential extension to atomic, spin, and color-center qubits.

Abstract

The QICK is a standalone open source qubit controller that was first introduced in 2022. In this follow-up work, we present recent experimental use cases that the QICK uniquely enabled for superconducting qubit systems. These include multiplexed signal generation and readout, mixer-free readout, pre-distorted fast flux pulses, and phase-coherent pulses for parametric operations, including high-fidelity parametric entangling gates. We explain in detail how the QICK was used to enable these experiments.

Figures (17)

• Figure 1: A typical superconducting qubit control loop using the QICK on the ZCU216 board. Drive pulses are filtered then amplified before being sent to the fridge. The readout pulse is filtered before being sent to the fridge. After the fridge, the readout pulse is amplified before being directly read into the ADC.
• Figure 2: Multiplexed signal generation. Frequency multiplexing is achieved by adding two or more single-frequency signal generators before the DAC module.
• Figure 3: Multiplexed readout. A polyphase filter bank (PFB) digitally demultiplexes the ADC samples into 8 channels with 50% overlap, to avoid gain losses over the entire bandwidth.
• Figure 4: (top) ZCU216 ADC analog gain as a function of analog input frequency. The transfer function is measured in 0.5 GHz steps at a constant input power of -7 dBm. The ADC sample rate is 2.4572 GHz. (bottom) ZCU216 ADC phase noise measured at $-1dBFS$ of power, in the range from 4 to 9 GHz $f_c$ and at delta frequencies from 100 Hz to 10 MHz from $f_c$.
• Figure 5: Qubit population measured with multiplexed readout. An example of a pulse sequence where four transmon qubits are driven sequentially with 2 consecutive $\pi$-pulses. The qubit populations are sampled simultaneously at 5 ns intervals over the span of the gate sequence, with the readout handled by just 1 DAC and 1 ADC on the QICK board.