High-Fidelity Control of Superconducting Qubits Using Direct Microwave Synthesis in Higher Nyquist Zones

Abstract

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-GHz radio-frequency digital-to-analog converters (RF 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.

arXiv comment12 pages, 9 figures

References in corpus (29)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer
• Charge insensitive qubit design derived from the Cooper pair box
• Surface codes: Towards practical large-scale quantum computation
• A Quantum Engineer's Guide to Superconducting Qubits
• Quantum Computing with Very Noisy Devices
• Simple pulses for elimination of leakage in weakly nonlinear qubits
• Dynamically protected cat-qubits: a new paradigm for universal quantum computation
• Procedure for systematically tuning up crosstalk in the cross resonance gate
• A simple all-microwave entangling gate for fixed-frequency superconducting qubits
• Characterizing Quantum Gates via Randomized Benchmarking
• Demonstration of Universal Parametric Entangling Gates on a Multi-Qubit Lattice
• Implementing optimal control pulse shaping for improved single-qubit gates
• Process verification of two-qubit quantum gates by randomized benchmarking
• Parametrically Activated Entangling Gates Using Transmon Qubits
• Gradient optimization of analytic controls: the route to high accuracy quantum optimal control
• First-order sideband transitions with flux-driven asymmetric transmon qubits
• First-principles analysis of cross-resonance gate operation
• Microwave-activated conditional-phase gate for superconducting qubits
• Gate-efficient simulation of molecular eigenstates on a quantum computer
• The impact of classical control electronics on qubit fidelity
• Operation and intrinsic error budget of a two-qubit cross-resonance gate
• Josephson Amplifier for Qubit Readout
• Hardware for Dynamic Quantum Computing
• High-fidelity measurement of qubits encoded in multilevel superconducting circuits
• Charting the circuit QED design landscape using optimal control theory
• Demonstration of a Parametrically-Activated Entangling Gate Protected from Flux Noise
• Demonstration of an All-Microwave Controlled-Phase Gate between Far Detuned Qubits
• High-fidelity dissipative engineering using parametric interactions

Cited by in corpus (10)

• Leakage reduction in fast superconducting qubit gates via optimal control
• The QICK (Quantum Instrumentation Control Kit): Readout and control for qubits and detectors
• ICARUS-Q: Integrated Control and Readout Unit for Scalable Quantum Processors
• IQ Mixer Calibration for Superconducting Circuits
• Experimental advances with the QICK (Quantum Instrumentation Control Kit) for superconducting quantum hardware
• Saturable Purcell filter for circuit quantum electrodynamics
• In situ mixer calibration for superconducting quantum circuits
• Qibosoq: an open-source framework for quantum circuit RFSoC programming
• On-demand shaped photon emission based on a parametrically modulated qubit
• Distributed-HISQ: A Distributed Quantum Control Architecture