Characterization of a Transmon Qubit in a 3D Cavity for Quantum Machine Learning and Photon Counting

Authors:
raw_author_name: Alessandro D’Elia
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy
raw_author_name: Leonardo Banchi
raw_affiliation_string: Dipartimento di Fisica e Astronomia, Universita di Firenze, 50019 Sesto Fiorentino, Italy; INFN—Sezione di Firenze, 50019 Sesto Fiorentino, Italy
raw_author_name: Matteo Beretta
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy
raw_author_name: Stefano Carrazza
raw_affiliation_string: CERN, Theoretical Physics Department, CH-1211 Geneva, Switzerland; INFN Sezione di Milano, Via Giovanni Celoria 16, 20133 Milan, Italy; Quantum Research Centre, Technology Innovation Institute, Abu Dhabi P.O. Box 9639, United Arab Emirates; TIF Lab, Dipartimento di Fisica, Università degli Studi di Milano, 20133 Milano, Italy
raw_author_name: Fabio Chiarello
raw_affiliation_string: Istituto di Fotonica e Nanotecnologie CNR, 00156 Roma, Italy
raw_author_name: Daniele Di Gioacchino
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy
raw_author_name: Andrea Giachero
raw_affiliation_string: Bicocca Quantum Technologies (BiQuTe) Centre, 20126 Milano, Italy; Dipartimento di Fisica, Università di Milano-Bicocca, 20126 Milano, Italy; INFN Sezione di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
raw_author_name: Alex Stephane Piedjou Komnang
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy
raw_author_name: Carlo Ligi
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy
raw_author_name: Giovanni Maccarrone
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy
raw_author_name: Andrea Pasquale
raw_affiliation_string: INFN Sezione di Milano, Via Giovanni Celoria 16, 20133 Milan, Italy; Quantum Research Centre, Technology Innovation Institute, Abu Dhabi P.O. Box 9639, United Arab Emirates; TIF Lab, Dipartimento di Fisica, Università degli Studi di Milano, 20133 Milano, Italy
raw_author_name: Luca Piersanti
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy
raw_author_name: Alessio Rettaroli
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy
raw_author_name: Matteo Robbiati
raw_affiliation_string: CERN, Theoretical Physics Department, CH-1211 Geneva, Switzerland; TIF Lab, Dipartimento di Fisica, Università degli Studi di Milano, 20133 Milano, Italy
raw_author_name: Simone Tocci
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy
raw_author_name: Claudio Gatti
raw_affiliation_string: INFN—Laboratori Nazionali di Frascati, 00044 Frascati, Italy

Abstract: In this paper, we report the use of a superconducting transmon qubit in a 3D cavity for quantum machine learning and photon counting applications. We first describe the realization and characterization of a transmon qubit coupled to a 3D resonator, providing a detailed description of the simulation framework and of the experimental measurement of important parameters, such as the dispersive shift and the qubit anharmonicity. We then report on a Quantum Machine Learning application implemented on a single-qubit device to fit the u-quark parton distribution function of the proton. In the final section of the manuscript, we present a new microwave photon detection scheme based on two qubits coupled to the same 3D resonator. This could in principle decrease the dark count rate, favoring applications like axion dark matter searches.