Fast high fidelity quantum non-demolition superconducting qubit readout
· Invited
Abstract
The most common technique of qubit readout in cQED relies on the transverse dispersive coupling between a qubit and a microwave cavity. However, despite important progresses, implementing fast high fidelity and QND readout remains a major challenge. Indeed, inferring the qubit state is limited by the trade-off between speed and accuracy due to Purcell effect and unwanted transitions induced by readout photons in the cavity. To overcome this, we propose and experimentally demonstrate a new readout scheme based on a transmon molecule inserted inside a 3D-cavity_[1,2]. The full system presents a transmon qubit mode coupled to a readout mode through an original non-pertubative cross-Kerr coupling. The readout mode, called polariton mode, results from the hybridization between the microwave cavity and the transmon molecule circuit. The direct cross-Kerr coupling is a key point of our readout scheme since it protects the qubit from Purcell effect. This first implementation, though perfectible, already enables a very efficient single-shot QND readout of the qubit in only 50ns, with a QND-ness of 99% and a fidelity of 97.4%.
[1] I. Diniz et al, Phys. Rev. A 87 033837 (2013).
[2] R. Dassonneville et al, arxiv 1905.0027 (2019).
[1] I. Diniz et al, Phys. Rev. A 87 033837 (2013).
[2] R. Dassonneville et al, arxiv 1905.0027 (2019).
*This work is supported by the French Agence Nationale de la Recherche (ANR-CE24-REQUIEM).
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Presenters
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Olivier Buisson
- Neel Institute, University Grenoble Alpes, CNRS
- Institut Neel
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
- Univ. Grenoble Alpes and Institut Néel, CNRS, 38000 Grenoble, France
- Université Grenoble Alpes, CNRS, Institut NEEL UPR2940, Grenoble, France