Entanglement generation and quantum information transfer between spatially-separated qubits in different cavities

TL;DR

This paper proposes a simplified method for generating entanglement and transferring quantum information between spatially-separated qubits in different cavities using a coupler qubit and virtual photon processes, suitable for current circuit QED systems.

Contribution

It introduces a minimal-step, pulse-free approach for entanglement and quantum transfer between distant qubits, reducing complexity and cavity decay effects.

Findings

High-fidelity entanglement achievable with superconducting qubits

Operation requires only one coupler qubit and one step

Method is feasible with current circuit QED technology

Abstract

The generation and control of quantum states of spatially-separated qubits distributed in different cavities constitute fundamental tasks in cavity quantum electrodynamics. An interesting question in this context is how to prepare entanglement and realize quantum information transfer between qubits located at different cavities, which are important in large-scale quantum information processing. In this paper, we consider a physical system consisting of two cavities and three qubits. Two of the qubits are placed in two different cavities while the remaining one acts as a coupler, which is used to connect the two cavities. We propose an approach for generating quantum entanglement and implementing quantum information transfer between the two spatially-separated intercavity qubits. The quantum operations involved in this proposal are performed by a virtual photon process, and thus the cavity decay is greatly suppressed during the operations. In addition, to complete the present tasks, only one coupler qubit and one operation step are needed. Moreover, there is no need of applying classical pulses, so that the engineering complexity is much reduced and the operation procedure is greatly simplified. Finally, our numerical results illustrate that high-fidelity implementation of this proposal using superconducting phase qubits and one-dimenstion transmision line resonators is feasible for current circuit QED implementations. This proposal can also be applied to other types of superconducting qubits, including flux and charge qubits.