Details

Autor(en) / Beteiligte

• Gusenkova, Daria
• Spiecker, Martin
• Gebauer, Richard
• Willsch, Madita
• Willsch, Dennis
• Valenti, Francesco
• Karcher, Nick
• Grünhaupt, Lukas
• Takmakov, Ivan
• Winkel, Patrick
• Rieger, Dennis
• Ustinov, Alexey V.
• Roch, Nicolas
• Wernsdorfer, Wolfgang
• Michielsen, Kristel
• Sander, Oliver
• Pop, Ioan M.

Titel

Quantum Nondemolition Dispersive Readout of a Superconducting Artificial Atom Using Large Photon Numbers

Ist Teil von

• Physical review applied, 2021-06, Vol.15 (6), Article 064030

Ort / Verlag

American Physical Society

Erscheinungsjahr

2021

Quelle

APS: American Physical Society E-Journals (Physics)

Beschreibungen/Notizen

• 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 n ¯ in the resonator enables a shorter measurement time and is therefore expected to reduce readout errors caused by spontaneous atom transitions. However, increasing n ¯ is generally observed to also monotonously increase these transition rates. Here we present a fluxonium artificial atom in which, despite the fact that the measured transition rates show nonmonotonous fluctuations within a factor of 6, for photon numbers up to n ¯ ≈200 , the signal-to-noise ratio continuously improves with increasing n ¯ . Even without the use of a parametric amplifier, at n ¯ =74 , we achieve fidelities of 99% and 93% for feedback-assisted ground and excited state preparations, respectively. At higher n ¯ , leakage outside the qubit computational space can no longer be neglected and it limits the fidelity of quantum state preparation.