Abstract We present protocols for the generation of high-dimensional entangled states of anharmonic oscillators by means of coherent manipulation of light-matter systems in the ultrastrong coupling regime. Our protocols consider a pair of ultrastrong coupled qubit-cavity systems, each coupled to an ancilla qubit, and combine classical pulses plus the selection rules imposed by the parity symmetry. We study the robustness of the entangling protocols under dissipative effects. This proposal may have applications within state-of-art circuit quantum electrodynamics.
We propose an efficient and robust protocol for the generation of entanglement between a superconducting qubit and a squeezed cavity. By applying a parametric drive to the cavity coupled to the qubit, the dynamical evolution of the system is precisely described by an anisotropic Rabi model within a squeezed reference frame. Utilizing high-order time-averaging methods, we analytically derive the resonance conditions and the effective Rabi frequency for the high-order three-photon process. By implementing an adiabatic passage, slowly tuning the cavity frequency across the resonance, the system is steered into a maximally entangled state, e.g., between the three-photon state
∣g,3⟩ and the qubit excited state
∣e,0⟩ in the squeezed picture. Numerical simulation results confirm the high fidelity and robustness of the proposed protocol. Our method provides a practical pathway for generating complex non-Gaussian entangled states, which are of significant value for fault-tolerant quantum computation and quantum metrology beyond the standard quantum limit.
A scheme is proposed to deterministically generate four-dimensional entangled states for two distant atoms trapped in two separate cavities via adiabatic passage by one step. An optimal expression of time-dependent Rabi frequencies is selected through numerical simulation. Numerical simulation also shows that the excited probabilities of the atoms, the cavity modes and the fiber modes are very low during adiabatic passage, and the scheme is insensitive to the fluctuation of experimental parameters. The four-dimensional entanglement may be generated with high fidelity with current experimental technology.