Perturbation impact of spectators on a cross-resonance gate in a tunable coupling superconducting circuit

Abstract

Cross-resonance (CR) gate has emerged as a promising scheme for fault-tolerant quantum computation with fixed-frequency qubits. We experimentally implement entangling CR gate by using a microwave-only control in a tunable coupling superconducting circuit, where the tunable coupler provides extra degrees of freedom to verify optimal condition for constructing CR gate. By developing three-qubit CR Hamiltonian tomography protocol, we systematically investigate the dependency of gate fidelities on spurious qubit interactions and present the first experimental approach to the evaluation of the perturbation impact arising from spectator qubits. Our results reveal that the spectator qubits lead to reductions in CR gate fidelity dependent on ZZ interaction and particular frequency detunings between spectator and gate qubits, demonstrating a more serious impact from the target spectator than from the control spectator. Our experiments uncover optimal CR operation regime and provide insight into an improvement of the CR gate by suppression of unwanted qubit interactions.

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• Scalable Method for Eliminating Residual $ZZ$ Interaction between Superconducting Qubits
• Coupler-Assisted Controlled-Phase Gate with Enhanced Adiabaticity
• Suppressing ZZ Crosstalk of Quantum Computers through Pulse and Scheduling Co-Optimization
• Tunable coupler to fully decouple and maximally localize superconducting qubits
• Cancelling microwave crosstalk with fixed-frequency qubits
• Correcting non-independent and non-identically distributed errors with surface codes
• Robust Quantum Gates against Correlated Noise in Integrated Quantum Chips
• Experimental error suppression in Cross-Resonance gates via multi-derivative pulse shaping
• An error-protected cross-resonance switch in weakly-tuneable architectures
• Role of parasitic interactions and microwave crosstalk in dispersive control of two superconducting artificial atoms
• Enabling High Performance Debugging for Variational Quantum Algorithms using Compressed Sensing
• High-performance multiqubit system with double-transmon couplers: Toward scalable superconducting quantum computers
• Error-mitigated deep-circuit quantum simulation of open systems: steady state and relaxation rate problems
• Lattice Hamiltonians and Stray Interactions Within Quantum Processors
• Scalable protocol to mitigate $ZZ$ crosstalk in universal quantum gates
• Implementing High-fidelity Two-Qubit Gates in Superconducting Coupler Architecture with Novel Parameter Regions
• Redundant string symmetry-based error correction: Demonstrations on quantum devices
• The perfect entangler spectrum as a tool to analyze crosstalk