Two-photon probe of the Jaynes-Cummings model and symmetry breaking in circuit QED

• Published in: arXiv.org
• Main Authors: Deppe, Frank, Mariantoni, Matteo, Menzel, E P, Marx, A, Saito, S, Kakuyanagi, K, Tanaka, H, Meno, T, Semba, K, Takayanagi, H, Solano, E, Gross, R
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 21.05.2008
• Subjects: Broken symmetry; Physics - Mesoscale and Nanoscale Physics; Physics - Quantum Physics; Physics - Superconductivity; Quantum electrodynamics; Quantum phenomena; Quantum theory; Qubits (quantum computing); Resonators; Superconductivity; Upconversion
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.0805.3294

Superconducting qubits behave as artificial two-level atoms and are used to investigate fundamental quantum phenomena. In this context, the study of multi-photon excitations occupies a central role. Moreover, coupling superconducting qubits to on-chip microwave resonators has given rise to the field of circuit QED. In contrast to quantum-optical cavity QED, circuit QED offers the tunability inherent to solid-state circuits. In this work, we report on the observation of key signatures of a two-photon driven Jaynes-Cummings model, which unveils the upconversion dynamics of a superconducting flux qubit coupled to an on-chip resonator. Our experiment and theoretical analysis show clear evidence for the coexistence of one- and two-photon driven level anticrossings of the qubit-resonator system. This results from the symmetry breaking of the system Hamiltonian, when parity becomes a not well-defined property. Our study provides deep insight into the interplay of multiphoton processes and symmetries in a qubit-resonator system.