Coupler-Assisted Controlled-Phase Gate with Enhanced Adiabaticity

Abstract

High-fidelity two-qubit entangling gates are essential building blocks for fault-tolerant quantum computers. Over the past decade, tremendous efforts have been made to develop scalable high-fidelity two-qubit gates with superconducting quantum circuits. Recently, an easy-to-scale controlled-phase gate scheme that utilizes the tunable-coupling architecture with fixed-frequency qubits [Phys. Rev. Lett. 125, 240502; Phys. Rev. Lett. 125, 240503] has been demonstrated with high fidelity and attracted broad interest. However, in-depth understanding of the underlying mechanism is still missing, preventing us from fully exploiting its potential. Here we present a comprehensive theoretical study, explaining the origin of the high-contrast ZZ interaction. Based on improved understanding, we develop a general yet convenient method for shaping an adiabatic pulse in a multilevel system, and identify how to optimize the gate performance from design. Given state-of-the-art coherence properties, we expect the scheme to potentially achieve a two-qubit gate error rate near $10^{-5}$, which would drastically speed up the progress towards fault-tolerant quantum computation.

22 pages, 11 figures

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• 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
• Coupling Superconducting Qubits via a Cavity Bus
• Demonstration of Two-Qubit Algorithms with a Superconducting Quantum Processor
• Characterization of addressability by simultaneous randomized benchmarking
• Demonstrating a Driven Reset Protocol of a Superconducting Qubit
• Initialization by measurement of a two-qubit superconducting circuit
• Microwave-Induced Cooling of a Superconducting Qubit
• Removing leakage-induced correlated errors in superconducting quantum error correction
• Parametric-resonance entangling gates with a tunable coupler
• Rapid and Unconditional Parametric Reset Protocol for Tunable Superconducting Qubits
• Floating tunable coupler for scalable quantum computing architectures

Cited by in corpus (23)

• Suppression of crosstalk in superconducting qubits using dynamical decoupling
• Long-distance transmon coupler with CZ gate fidelity above $99.8\%$
• Scalable algorithm simplification using quantum AND logic
• Experimental Realization of Two Qutrits Gate with Tunable Coupling in Superconducting Circuits
• Scalable Method for Eliminating Residual $ZZ$ Interaction between Superconducting Qubits
• Realization of High-Fidelity CZ Gate based on a Double-Transmon Coupler
• Controlled-Controlled-Phase Gates for Superconducting Qubits Mediated by a Shared Tunable Coupler
• Coupler-Assisted Leakage Reduction for Scalable Quantum Error Correction with Superconducting Qubits
• Superconducting coupler with exponentially large on-off ratio
• Co-Design quantum simulation of nanoscale NMR
• Direct calculation of the ZZ-interaction rates in the multi-mode circuit-QED
• High-performance multiqubit system with double-transmon couplers: Toward scalable superconducting quantum computers
• Charge-parity switching effects and optimisation of transmon-qubit design parameters
• Scalable protocol to mitigate $ZZ$ crosstalk in universal quantum gates
• Capacitively Shunted Double-Transmon Coupler Realizing Bias-Free Idling and High-Fidelity CZ Gate
• Above 99.9% Fidelity Single-Qubit Gates, Two-Qubit Gates, and Readout in a Single Superconducting Quantum Device
• Integrating Quantum Processor Device and Control Optimization in a Gradient-based Framework
• Superconducting qubits in the millions: the potential and limitations of modularity
• Benchmarking Digital-Analog Quantum Computation
• Application of Optimal Control to Time-Resolution Protocol for Quantum Sensing
• Tunable Hybrid-Mode Coupler Enabling Strong Interactions between Transmons at Centimeter-Scale Distance
• Microwave-activated high-fidelity three-qubit gate scheme for fixed-frequency superconducting qubits
• Transmon-assisted high-fidelity controlled-Z gates for integer fluxonium qubits