Print Email Facebook Twitter Observation of the Bloch-Siegert Shift in a Qubit-Oscillator System in the Ultrastrong Coupling Regime Title Observation of the Bloch-Siegert Shift in a Qubit-Oscillator System in the Ultrastrong Coupling Regime Author Forn-Díaz, P. Lisenfeld, J. Marcos, D. García-Ripoll, J.J. Solano, E. Harmans, C.J.P.M. Mooij, J.E. Faculty Applied Sciences Department QN/Quantum Nanoscience Date 2010-11-30 Abstract We measure the dispersive energy-level shift of an LC resonator magnetically coupled to a superconducting qubit, which clearly shows that our system operates in the ultrastrong coupling regime. The large mutual kinetic inductance provides a coupling energy of ?0.82??GHz, requiring the addition of counter-rotating-wave terms in the description of the Jaynes-Cummings model. We find a 50 MHz Bloch-Siegert shift when the qubit is in its symmetry point, fully consistent with our analytical model. To reference this document use: http://resolver.tudelft.nl/uuid:77169d5c-306d-4715-b04d-c6c5d35051a0 DOI https://doi.org/10.1103/PhysRevLett.105.237001 Publisher American Physical Society ISSN 0031-9007 Source Physical Review Letters, 105 (23), 2010 Part of collection Institutional Repository Document type journal article Rights (c) 2010 The Author(s)American Physical Society Files PDF Forn-Diaz2010.pdf 718.69 KB Close viewer /islandora/object/uuid:77169d5c-306d-4715-b04d-c6c5d35051a0/datastream/OBJ/view