Circuit QED: cross-Kerr effect induced by a superconducting qutrit without classical pulses

Abstract

The realization of cross-Kerr nonlinearity is an important task for many applications in quantum information processing. In this work, we propose a method for realizing cross-Kerr nonlinearity interaction between two superconducting coplanar waveguide resonators coupled by a three-level superconducting flux qutrit (coupler). By employing the qutrit-resonator dispersive interaction, we derive an effective Hamiltonian involving two-photon number operators and a coupler operator. This Hamiltonian can be used to describe a cross-Kerr nonlinearity interaction between two resonators when the coupler is in the ground state. Because the coupler is unexcited during the entire process, the effect of coupler decoherence can be greatly minimized. More importantly, compared with the previous proposals, our proposal does not require classical pulses. Furthermore, due to use of only a three-level qutrit, the experimental setup is much simplified when compared with previous proposals requiring a four-level artificial atomic systems. Based on our Hamiltonian, we implement a two-resonator qubits controlled-phase gate and generate a two-resonator entangled coherent state. Numerical simulation shows that the high-fidelity implementation of the phase gate and creation of the entangled coherent state are feasible with current circuit QED technology.

Limit Cycle Phase and Goldstone Mode in Driven Dissipative Systems

“…Concerning the experimental realizations, the model and the results are applicable to a wide variety of driven-dissipative interacting bosonic platforms, including circuit-QED, semiconductor excitons, and multimode cavities with cold-atoms 29,49 , where the figure of merit V 0 /γ can be tuned, properly. It is also interesting to explore the feasibility of using such platforms in creating non-Gaussian states as an instrumental ingredient for quantum information protocols based on continuous variable entanglement and photonic quantum logic gates 14,[50][51][52] .…”

“…In that regard and as a suitable testbed, driven-dissipative quantum systems and their phase transitions have been the subject of many studies. Observation of exciton-polariton BEC in semiconductors 5,6 and cuprites 7 and their superfluidity 8,9 , probing the first-order phase transitions, dynamical hysteresis, and Kibble-Zurek quench mechanism in microcavities 10,11 , and demonstration of dynamical bifurcation and optical bistability in circuit QED [12][13][14][15][16][17] are a few examples of rapidly growing body of experimental explorations of such physics in different platforms.…”

Logical measurement-based quantum computation in circuit-QED

“…In fact, the entangled coherent state can be used as a simplest resource state for MBQC with no error-correction because CV quantum teleportation, which is the building block for MBQC, has been demonstrated in quantum optics 60–63 and investigated in circuit-QED 64 . The similar method of implementing the states has been suggested with the assumption of the cross-Kerr interaction in a circuit-QED system 65 .…”

Creation of superposition of arbitrary states encoded in two high-Q cavities

“…Hence, 3D cavities are good memory elements, which can have coherence time at least four orders of magnitude longer than the transmons. By encoding quantum information in microwave cavities, many schemes have been proposed for synthesizing Bell states [19], NOON states [20][21][22][23][24][25][26], and entangled coherent states [27,28] of multiple cavities, and realizing cross-Kerr nonlinearity interaction between two cavities [29,30].…”