VietNam 2013 

IXth Rencontres du Vietnam
Quy-Nhon, August 4-10, 2013


 Nanophysics: from fundamentals to applications

(the return)


Tuesday 6
Quantum electronics, quantum information, electronic quantum optics, high frequency noise

› 16:30 - 17:00 (30min)
Ultrastrong Coupling on Circuit-QED Systems and Their Arrays
Mahn-Soo Choi  1@  , Myung-Joong Hwang  2@  
1 : Department of Physics, Korea University
Seoul 136-713 -  South Korea
2 : Department of Physics, POSTECH
Pohang 790-784 -  South Korea

We study the non-classical behaviors and low-lying excitations of single circuit-QED systems (cQEDs) and chains of cQEDs. We first revisit the variational solution of a single cQED, suggest a new trial wave function, and demonstrate its accuracy on the quantum correlation effects. We then turn to the effect of ultrastrong cavity-qubit coupling on the low-lying excitations of a chain of coupled circuit-QED systems. In the presence of the on-site ultrastrong coupling, the photon hopping between cavities can be mapped to the Ising interaction between the lowest two-levels of individual cQEDs of the chain. The resulting effective Hamiltonian exhibits two nearly-degenerate ground states whose wave functions involve maximal entanglement between the macroscopic quantum states of the cavities and the states of qubits. We show that they are mathematically equivalent to Majorana bound states. Further, we devise a scheme for the dispersive measurement of the ground states using an additional resonator attached to one end of the circuit-QED chain. Finally, we discuss the effects of disorders and local noises on the coherence of the ground states.

[1] M.-J. Hwang and M.-S. Choi, To appear in Phys. Rev. B; arXiv: 1207.0088.

[2] M.-J. Hwang and M.-S. Choi, Phys. Rev. A 82, 025802 (2010).

Online user: 1 RSS Feed