High-Coherence Fluxonium Qubit

@article{Nguyen2019HighCoherenceFQ,
  title={High-Coherence Fluxonium Qubit},
  author={Long B. Nguyen and Yen-Hsiang Lin and Aaron Somoroff and Raymond A. Mencia and Nicholas Grabon and Vladimir E Manucharyan},
  journal={Physical Review X},
  year={2019}
}
We report superconducting fluxonium qubits with coherence times largely limited by energy relaxation and reproducibly satisfying T2 > 100 microseconds (T2 > 300 microseconds in one device). Moreover, given the state of the art values of the surface loss tangent and the 1/f flux noise amplitude, coherence can be further improved beyond 1 millisecond. Our results violate a common viewpoint that the number of Josephson junctions in a superconducting circuit -- over 100 here -- must be minimized… 

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References

SHOWING 1-10 OF 120 REFERENCES
High-coherence hybrid superconducting qubit.
TLDR
It is reported that quantum coherence measurements of a superconducting qubit whose design is a hybrid of several existing types, and its sign is reversed compared with most other popular qubit designs.
Fluctuations of Energy-Relaxation Times in Superconducting Qubits.
TLDR
This research uses qubits as spectral and temporal probes of individual two-level-system defects to provide direct evidence that they are responsible for the largest fluctuations in superconducting qubits.
Microwave-activated controlled- Z gate for fixed-frequency fluxonium qubits
The superconducting fluxonium circuit is an artificial atom with a strongly anharmonic spectrum: when biased at a half flux quantum, the lowest qubit transition is an order of magnitude smaller in
The flux qubit revisited to enhance coherence and reproducibility
TLDR
The design and fabrication of the superconducting flux qubit is revisited, achieving a planar device with broad-frequency tunability, strong anharmonicity, high reproducibility and relaxation times in excess of 40 μs at its flux-insensitive point.
Nanowire Superinductance Fluxonium Qubit.
TLDR
A crossover in the lifetime limiting mechanism from capacitive to inductive losses is found and is explained by means of a multimode theory accounting for the distributed nature of the superinductance and the effect of the circuit nonlinearity to all orders in the Josephson potential.
Superconducting Circuits for Quantum Information: An Outlook
TLDR
For the first time, physicists will have to master quantum error correction to design and operate complex active systems that are dissipative in nature, yet remain coherent indefinitely.
Collective modes in the fluxonium qubit
Superconducting qubit designs vary in complexity from single- and few-junction systems, such as the transmon and flux qubits, to the many-junction fluxonium. Here, we consider the question of whether
Simultaneous Monitoring of Fluxonium Qubits in a Waveguide
Most quantum-error correcting codes assume that the decoherence of each physical qubit is independent of the decoherence of any other physical qubit. We can test the validity of this assumption in an
Model for 1/f Flux noise in SQUIDs and Qubits.
TLDR
Simulations of the noise produced by randomly oriented defects with a density of 5x10(17) m(-2) yield 1/f noise magnitudes in good agreement with experiments.
ac Stark shift and dephasing of a superconducting qubit strongly coupled to a cavity field.
TLDR
Spectroscopy of a superconducting charge qubit coupled nonresonantly to a single mode of an on-chip resonator and a crossover in line shape with measurement power is observed and theoretically explained.
...
...