Fast microwave-driven two-qubit gates between fluxonium qubits with a transmon coupler

Abstract

Two qubit gates constitute fundamental building blocks in the realization of large-scale quantum devices. Using superconducting circuits, two-qubit gates have previously been implemented in different ways with each method aiming to maximize gate fidelity. Another important goal of a new gate scheme is to minimize the complexity of gate calibration. In this work, we demonstrate a high-fidelity two-qubit gate between two fluxonium qubits enabled by an intermediate capacitively coupled transmon. The coupling strengths between the qubits and the coupler are designed to minimize residual crosstalk while still allowing for fast gate operations. The gate is based on frequency selectively exciting the coupler using a microwave drive to complete a 2$\pi$ rotation, conditional on the state of the fluxonium qubits. When successful, this drive scheme implements a conditional phase gate. Using analytically derived pulse shapes, we minimize unwanted excitations of the coupler and obtain gate errors of $10^{-2}$ for gate times below 60~ns. At longer durations, our gate is limited by relaxation of the coupler. Our results show how carefully designed control pulses can speed up frequency selective entangling gates.

References in corpus (56)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• Charge insensitive qubit design derived from the Cooper pair box
• Surface codes: Towards practical large-scale quantum computation
• Demonstration of Two-Qubit Algorithms with a Superconducting Quantum Processor
• Suppressing quantum errors by scaling a surface code logical qubit
• Simple pulses for elimination of leakage in weakly nonlinear qubits
• Fluxonium: single Cooper pair circuit free of charge offsets
• Quantum error correction below the surface code threshold
• Efficient Z-Gates for Quantum Computing
• 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
• Robust determination of molecular spectra on a quantum processor
• A tunable coupling scheme for implementing high-fidelity two-qubit gates
• Repeated Quantum Error Detection in a Surface Code
• Realization of high-fidelity CZ and ZZ-free iSWAP gates with a tunable coupler
• Optimal quantum control using randomized benchmarking
• Reducing intrinsic loss in superconducting resonators by surface treatment and deep etching of silicon substrates
• Parametrically Activated Entangling Gates Using Transmon Qubits
• Quantum electrodynamics in a topological waveguide
• Scalable quantum circuit and control for a superconducting surface code
• Leakage reduction in fast superconducting qubit gates via optimal control
• Implementation of Conditional-Phase Gates based on tunable ZZ-Interactions
• Logical-qubit operations in an error-detecting surface code
• High-Fidelity, Frequency-Flexible Two-Qubit Fluxonium Gates with a Transmon Coupler
• Reducing unitary and spectator errors in cross resonance with optimized rotary echoes
• Microwave-activated conditional-phase gate for superconducting qubits
• Universal fast flux control of a coherent, low-frequency qubit
• Characterization and Reduction of Capacitive Loss Induced by Sub-Micron Josephson Junction Fabrication in Superconducting Qubits
• Realization of a $\Lambda$ system with metastable states of a capacitively-shunted fluxonium
• High fidelity two-qubit gates on fluxoniums using a tunable coupler
• Diabatic gates for frequency-tunable superconducting qubits
• Hardware-efficient quantum error correction via concatenated bosonic qubits
• Overcoming leakage in scalable quantum error correction
• Parametric-resonance entangling gates with a tunable coupler
• Hardware-Efficient Microwave-Activated Tunable Coupling Between Superconducting Qubits
• Benchmarking Coherent Errors in Controlled-Phase Gates due to Spectator Qubits
• Long-distance transmon coupler with CZ gate fidelity above $99.8\%$
• Fast logic with slow qubits: microwave-activated controlled-Z gate on low-frequency fluxoniums
• Reducing leakage of single-qubit gates for superconducting quantum processors using analytical control pulse envelopes
• Precision measurement of the microwave dielectric loss of sapphire in the quantum regime with parts-per-billion sensitivity
• All-microwave leakage reduction units for quantum error correction with superconducting transmon qubits
• Microwave-Activated Controlled-Z Gate for Fixed-Frequency Fluxonium Qubits
• Realization of high-fidelity CZ gates in extensible superconducting qubits design with a tunable coupler
• Benchmarking digital quantum simulations above hundreds of qubits using quantum critical dynamics
• Implementing a synthetic magnetic vector potential in a 2D superconducting qubit array
• Coupler microwave-activated controlled phase gate on fluxonium qubits
• Native approach to controlled-Z gates in inductively coupled fluxonium qubits
• Wafer-scale uniformity of Dolan-bridge and bridgeless Manhattan-style Josephson junctions for superconducting quantum processors
• High coherence fluxonium manufactured with a wafer-scale uniformity process
• Mitigating Losses of Superconducting Qubits Strongly Coupled to Defect Modes
• Collective bosonic effects in an array of transmon devices
• Algorithms for perturbative analysis and simulation of quantum dynamics
• Floquet Analysis of Frequency Collisions
• Hands-on Introduction to Randomized Benchmarking
• Single-Qubit Gates Beyond the Rotating-Wave Approximation for Strongly Anharmonic Low-Frequency Qubits