Current state of the art quantum computing experiments in the microwave regime use control pulses generated by modulating microwave tones with baseband signals generated by an arbitrary waveform generator (AWG). Recent advances in digital analog conversion technology have made it possible to directly synthesize arbitrary microwave pulses with sampling rates up to 92 gigasamples per second (GS/s). These new high bandwidth AWG's could dramatically simplify the classical control chain for quantum computing experiments, enabling more advanced pulse shaping and reducing the number of components that need to be carefully calibrated. Here we use a high speed AWG to study the viability of such a simplified scheme. We characterize the AWG and perform randomized benchmarking of a superconducting qubit, achieving average single qubit gate error rates below $5\times10^{-4}$.
Current state of the art quantum computing experiments in the microwave regime use control pulses generated by modulating microwave tones with baseband signals generated by an arbitrary waveform generator (AWG). Recent advances in digital analog conversion technology have made it possible to directly synthesize arbitrary microwave pulses with sampling rates up to 92 gigasamples per second (GS/s). These new high bandwidth AWG's could dramatically simplify the classical control chain for quantum computing experiments, enabling more advanced pulse shaping and reducing the number of components that need to be carefully calibrated. Here we use a high speed AWG to study the viability of such a simplified scheme. We characterize the AWG and perform randomized benchmarking of a superconducting qubit, achieving average single qubit gate error rates below 5×10−4.
Superconducting quantum processors are manufactured based on a semiconductor process, which makes qubit integration possible. At the same time, this kind of qubit exhibits high-performance fidelity and decoherence time and requires a programmable arbitrary waveform generator (AWG). This paper presents the implementation of an AWG with a sampling rate of two-gigabit samples per second as well as 16-bit vertical resolution digital-to-analog converters. The AWGs are designed for a scaled-up usage scenario by integrating them with separate microwave devices onto a single backplane. A special waveform sequence output controller is designed to realize seamless waveform switching and arbitrary waveform generation. The jitter of multiple AWG channels is around 10 ps, and the integral nonlinearity and differential nonlinearity are both about 2 least significant bits. This customizable AWG has been used in several superconducting quantum processors, and the result of multiple qubits’ measurement verifies that the AWG is qualified for controlling tens of superconducting qubits.
Multi-tone microwave signals are crucial for advanced quantum computing applications, including frequency-multiplexed qubit control and simultaneous two-qubit gate execution. However, interference among microwave signal components can cause signal amplitudes to surpass the output limits of an arbitrary waveform generator (AWG), hindering the generation of precise signals necessary for accurate qubit manipulation. To address this issue, we introduce a method that adjusts the phase of individual microwave signal components, effectively reducing interference and maintaining signal amplitude within the AWG’s operational range.
Control electronics for superconducting quantum processors have strict requirements for accurate command of the sensitive quantum states of their qubits. Hinging on the purity of ultra-phase-stable oscillators to upconvert very-low-noise baseband pulses, conventional control systems can become prohibitively complex and expensive when scaling to larger quantum devices, especially as high sampling rates become desirable for fine-grained pulse shaping. Few-gigahertz radio-frequency (RF) digital-to-analog converters (DACs) present a more economical avenue for high-fidelity control while simultaneously providing greater command over the spectrum of the synthesized signal. Modern RF DACs with extra-wide bandwidths are able to directly synthesize tones above their sampling rates, thereby keeping the system clock rate at a level compatible with modern digital logic systems while still being able to generate high-frequency pulses with arbitrary profiles. We have incorporated custom superconducting qubit control logic into off-the-shelf hardware capable of low-noise pulse synthesis up to 7.5 GHz using an RF DAC clocked at 5 GHz. Our approach enables highly linear and stable microwave synthesis over a wide bandwidth, giving rise to high-resolution control and a reduced number of required signal sources per qubit. We characterize the performance of the hardware using a five-transmon superconducting device and demonstrate consistently reduced two-qubit gate error (as low as 1.8%), which we show results from superior control chain linearity compared to traditional configurations. The exceptional flexibility and stability further establish a foundation for scalable quantum control beyond intermediate-scale devices.
This paper reports the development of a low-latency arbitrary waveform generator (AWG), which is suitable for the control and measurement of superconducting quantum computers. It can generate qubit control signals and measurement signals in real time. Compared with commercial AWG, our AWG has less latency and higher analog bandwidth. Compressing latency can reduce system feedback time, and higher analog bandwidth improves the system's integration by mounting more qubits on the readout line. The AWG integrates four high-speed digital-to-analog converters (DACs), phase-locked loop (PLL) circuits, field-programmable gate arrays (FPGAs), and related circuits into a standard PXI 3U board. The waveform generator module, communication interface module, clock module, and configuration module are realized utilizing the FPGA. The FPGA-based hardware architecture enables AWG to be flexibly configured to meet the various needs of quantum experiments. The four-channel AWG has a 2-GSa/s sampling rate, a 14-bit resolution, and 500 MHz bandwidth. The jitter in the AWG output waveform is approximately 3 ps; the latency of the AWG (the time from the feedback trigger received until a feedback pulse is generated) is approximately 55 ns. These designs form the basis of realizing control system for large-scale quantum computing.
Superconducting quantum computer is manufactured based on semiconductor process which makes qubits integration possible. At the same time, this kind of qubit exhibits high performance fidelity, de-coherence time, scalability and requires a programmable arbitrary waveform generator (AWG). This paper presents implementation of an AWG which composed of two gigabit samples per second (GSPS) sampling rate, 16 bit vertical resolution digital to analog converters (DACs). The AWG integrated with separate microwave devices onto a metal plate for the scale-up consideration. A special waveform sequence output controller is designed to realize seamless waveform switching and arbitrary waveform generator. The jitter in multiple AWG channels is around 10ps, Integral nonlinearity (INL) as well as differential nonlinearity (DNL) is about 2 LSB, and the qubit performance of the de-coherence time (T2*) achieved 33% promotion over that of a commercial 1 GSPS, 14 bit AWG.
High-fidelity control of superconducting qubits requires carefully shaped microwave pulses to avoid several different kinds of error at once. This article is a pedagogical bridging text aimed at upper-level undergraduate and early graduate students who have completed an introductory quantum mechanics course and a first course in quantum computing or quantum information, but who have not yet encountered the physical implementation of qubit gates. We integrate physical intuition for pulse design, analytical gate-level descriptions, and practical hardware considerations into a single, derivation-driven narrative, with explicit learning objectives. We begin with simple pulse envelopes and their spectral properties, showing how finite bandwidth produces leakage outside the computational subspace. This motivates the derivative removal by adiabatic gate (DRAG) technique, which we derive explicitly using the Magnus expansion, obtaining a clear, order-by-order account of which physical error channel appears at which order and why DRAG's cancellation is necessarily incomplete. We discuss the practical hardware realities of control pulse generation, focusing on arbitrary waveform generators (AWG), local oscillators (LO), and IQ mixing. Finally, we extend the discussion to two-qubit operation via the cross-resonance gate, and interpret how driving the control qubit at the target qubit's transition frequency necessarily produces several unwanted interaction terms alongside the desired one, and how successive generations of pulse-engineering strategies have been designed to suppress them.