Millisecond coherence in a superconducting qubit

Abstract

Increasing the degree of control over physical qubits is a crucial component of quantum computing research. We report a superconducting qubit of fluxonium type with the Ramsey coherence time reaching $T_2^{\ast }=1.48\pm 0.13\mathrm{ms}$, which exceeds the state of the art value by an order of magnitude. As a result, the average single-qubit gate fidelity grew above $0.9999$, surpassing, to our knowledge, any other solid-state quantum system. Furthermore, by measuring energy relaxation of the parity-forbidden transition to second excited state, we exclude the effect of out-of-equilibrium quasiparticles on coherence in our circuit. Combined with recent demonstrations of two-qubit gates on fluxoniums, our result paves the way for the next generation of quantum processors.

Cited by in corpus (11)

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• Robust and Efficient Hamiltonian Learning
• FPGA-based electronic system for the control and readout of superconducting quantum processors
• Qubit-compatible substrates with superconducting through-silicon vias
• Stabilizing and improving qubit coherence by engineering noise spectrum of two-level systems
• Fast Flux Entangling Gate for Fluxonium Circuits
• Strain-spectroscopy of strongly interacting defects in superconducting qubits
• High-Order Qubit Dephasing at Sweet Spots by Non-Gaussian Fluctuators: Symmetry Breaking and Floquet Protection
• Protection of quantum information in a chain of Josephson junctions
• The resource cost of large scale quantum computing