Quantum non-demolition dispersive readout of a superconducting artificial atom using large photon numbers
| Autor: | Madita Willsch, Nick Karcher, Martin Spiecker, Ivan Takmakov, Ioan Pop, Dennis Rieger, Lukas Grünhaupt, Dennis Willsch, Wolfgang Wernsdorfer, Oliver Sander, Patrick Winkel, Alexey V. Ustinov, Nicolas Roch, Richard Gebauer, Daria Gusenkova, Kristel Michielsen, Francesco Valenti |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Physical review applied 15(6), 064030 (2021). doi:10.1103/PhysRevApplied.15.064030 Physical review applied, 15 (6), Art. Nr.: 064030 |
| ISSN: | 2331-7019 |
| DOI: | 10.48550/arxiv.2009.14785 |
| Popis: | Reading out the state of superconducting artificial atoms typically relies on dispersive coupling to a readout resonator. For a given system noise temperature, increasing the circulating photon number $\bar{n}$ in the resonator enables a shorter measurement time and is therefore expected to reduce readout errors caused by spontaneous atom transitions. However, increasing $\bar{n}$ is generally observed to also increase these transition rates. Here we present a fluxonium artificial atom in which we measure an overall flat dependence of the transition rates between its first two states as a function of $\bar{n}$, up to $\bar{n}\approx200$. Despite the fact that we observe the expected decrease of the dispersive shift with increasing readout power, the signal-to-noise ratio continuously improves with increasing $\bar{n}$. Even without the use of a parametric amplifier, at $\bar{n}=74$, we measure fidelities of 99% and 93% for feedback-assisted ground and excited state preparation, respectively. Comment: typos corrected, added figure at p.10 (section IV of the Supplemental Material), added references |
| Databáze: | OpenAIRE |
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