Nanowire Superinductance Fluxonium Qubit

Area of Science:

• Quantum computing
• Superconducting circuits
• Solid-state physics

Background:

• Fluxonium qubits are promising for quantum computation.
• Superinductances enhance qubit performance.
• Understanding loss mechanisms is crucial for qubit development.

Purpose of the Study:

• Characterize a novel fluxonium qubit.
• Explain its energy spectrum using multimode theory.
• Measure and analyze the qubit's excited state lifetime.

Main Methods:

• Fabrication of a fluxonium qubit using a NbTiN nanowire superinductance.
• Multimode theory to model the energy spectrum.
• Multiphoton Raman spectroscopy to probe transitions and measure lifetime.

Main Results:

• Measured energy spectrum explained by multimode theory.
• Observed multilevel Autler-Townes splitting.
• Determined an excited state lifetime (T1) of 20 μs.
• Identified a crossover in lifetime-limiting mechanisms (capacitive to inductive losses) with varying magnetic flux.

Conclusions:

• The developed fluxonium qubit shows potential for quantum applications.
• Multimode theory accurately describes the qubit's behavior.
• Understanding loss mechanisms provides a pathway for qubit optimization.