Quantum phases in circuit QED with a superconducting qubit array

• Published in: Scientific reports Vol. 4; no. 1; p. 4083
• Main Authors: Zhang, Yuanwei, Yu, Lixian, Liang, J. -Q, Chen, Gang, Jia, Suotang, Nori, Franco
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 13.02.2014; Nature Publishing Group
• Subjects: 639/766/400/482; 639/766/483/481; Competition; Humanities and Social Sciences; multidisciplinary; Nearest-neighbor; Optics; Science; Superconductors
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep04083

Circuit QED on a chip has become a powerful platform for simulating complex many-body physics. In this report, we realize a Dicke-Ising model with an antiferromagnetic nearest-neighbor spin-spin interaction in circuit QED with a superconducting qubit array. We show that this system exhibits a competition between the collective spin-photon interaction and the antiferromagnetic nearest-neighbor spin-spin interaction and then predict four quantum phases, including: a paramagnetic normal phase, an antiferromagnetic normal phase, a paramagnetic superradiant phase and an antiferromagnetic superradiant phase. The antiferromagnetic normal phase and the antiferromagnetic superradiant phase are new phases in many-body quantum optics. In the antiferromagnetic superradiant phase, both the antiferromagnetic and superradiant orders can coexist and thus the system possesses symmetry. Moreover, we find an unconventional photon signature in this phase. In future experiments, these predicted quantum phases could be distinguished by detecting both the mean-photon number and the magnetization.