Cross-Kerr-effect induced by coupled Josephson qubits in circuit quantum electrodynamics

Abstract

We propose a scheme for implementing cross Kerr nonlinearity between two superconducting transmission line resonators (TLR) via their interaction with a coupler which is constructed by two superconducting charge qubits connected to each other via a superconducting quantum interference device. When suitably driven, the coupler can induce very strong cross phase modulation (XPM) between the two TLRs due to its N-type level structure and the consequent electromagnetically induced transparency in its lowest states. The flexibility of our design can lead to various inter-TLR coupling configurations. The obtained cross Kerr coefficient is large enough to allow many important quantum operations in which only few photons are involved. We further show that this scheme is very robust against the fluctuations in solid state circuits. Our numerical calculations imply that the absorption and dispersion resulted from the decoherence of the coupler are very small compared with the strength of the proposed XPM.

Efficient and flexible protocol for implementing two-qubit controlled phase gates with cross-Kerr nonlinearity

“…Meanwhile, numerous protocols have also been proposed to construct a QND with high efficiency. Some protocols [52][53][54][55] have studied the properties of the cross-Kerr nonlinearity with the purpose of improving the existing QNDs. For example, Lin et al [52] have plotted a Poisson distribution figure of the measured output qubus beam photon numbers with the Downloaded by [Eindhoven Technical University] at 01: 54 20 October 2014 proper phase shifts θ = 0.05 and |γ | = 100.…”

Some implications of superconducting quantum interference to the application of master equations in engineering quantum technologies

“…(10) We note that there is increasing interest on the effect of non-linear couplings between systems (such as those with a Kerr type nonlinearity) 25,26 . In such circumstances, as here, the approximations used in the standard derivation of the master equation would need to be examined in detail.…”

Coexistence of three-wave, four-wave, and five-wave mixing processes in a superconducting artificial atom

“…In a series of previous works many quantum optical phenomena, such as sideband transitions [10], dynamical Casimir effect [11], cross-Kerr nonlinearity [12], and quantum Zeno effect [13] have been successfully demonstrated in superconducting circuits. In contrast to naturally occurring atoms, superconducting qubits [14], which are the key components of these circuits and behave as quantum multilevel artificial atoms, can be engineered to tailor their characteristic frequencies and energy-level structures by adjusting external parameters.…”