Electromagnetic response properties of fluxonium atom

Electromagnetic Response of Fluxonium. Hessa M. Alotaibi1, 2, and Barry C. Sanders1 1Institute for Quantum Information Science, University of Calgary, Alberta T2N 1N4, Canada 2 Public Authority for Applied Education and Training, P.O. Box No. 23167, Safat 13092 Kuwait Fluxonium is especially promising as an artificial atom in a superconducting circuit because it admits a few electronic levels with low loss and decoherence [1]. These advantages arise because fluxonium has a multiple well potential whose properties are controlled by an external magnetic field. Fluxonium has previously been shown to be capable of exhibiting electromagnetically induced transparency and a new phenomenon known as electromagnetically induced transparency with amplification by operating with three electronic levels [2]. We study the electromagnetic response properties of fluxonium, which has been engineered to have four well-behaved electronic levels. Our theoretical analysis, based on solving density-matrix master equations with classical driving fields, shows two transparency windows in the spectral response profile with locations determined by detunings of the weak signal and strong driving fields. The strong driving field can also be used to control transparency window width, dispersion and group velocity of the pulse. In particular we show that a significant reduction of the group velocities and also matching of the group velocities of the two signal fields are achievable for strong driving fields in accordance with predictions for optical systems [3, 4]. We show that judiciously chosen control parameters such as driving field strength can yield the existence of a point in the spectrum where the transparency windows for the two weak fields coincide for slightly different energy detunings, which ensures that field nonlinearities do not vanish, thereby enabling cross-phase modulation of the two signal fields. These results could be valuable for applications to quantum memory and quantum phase gates. [1] Vladimir E. Manucharyan, Jens Koch, Leonid I. Glazman, Michel H. Devoret, Science 326, 113 (2009). [2] Jaewoo Joo, Jérôme Bourassa, Alexandre Blais, and Barry C. Sanders, Phys. Rev. Lett. 105, 073601 (2010). [3] S. Rébic, D. Vitali, C. Ottaviani, P. Tombesi, M. Artoni, F. Cataliotti, and R. Corbalan, Phys. Rev. A. 70, 032317 (2004). [4] Amitabh Joshi, and Min Xiao, Phys. Rev. A. 72, 062319 (2005).