Abstract
The generation and control of quantum states of spatially-separated qubits distributed in different cavities constitute fundamental tasks in cavity quantum electrodynamics (QED). 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 inter-cavity qubits. The quantum operations involved in this proposal are performed by a virtual photon process; thus the cavity decay is greatly suppressed during operations. In addition, to complete these tasks, only one coupler qubit and one operation step are needed. Moreover, there is no need to apply 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-dimensional transmission 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.
Highlights
There exist several physical systems in which a quantum bus could be realized
The method presented here is quite general, and can be applied to accomplish the same task with the coupler qubit replaced by a different type of qubit such as a quantum dot, or with the two intercavity qubits replaced by other two qubits such as two atoms, two quantum dots, two NV centers and so on
We have proposed a method to generate quantum entanglement and perform quantum information transfer between two spatially-separate superconducting qubits residing in two different cavities
Summary
There exist several physical systems in which a quantum bus could be realized. One example is trapped ions [1,2], in which various quantum operations and algorithms have been performed by employing the quantized motion of the ions (phonons) as the bus. A large number of theoretical proposals have been presented for realizing quantum information transfer, logical gates, and entanglement with two or more superconducting qubits embedded in a cavity or coupled by a resonator [23,24,25,26,27,28,29,30,31,32]. Considerable experimental and theoretical work has been devoted recently to the investigation of QIP in a system consisting of two or more than two cavities, each hosting (and coupled) to multiple qubits In this kind of architecture, quantum operations would be performed on qubits in the same cavity, and on qubits or photons in different cavities.
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