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arXiv · 1305.1226

Ground state of three qubits coupled to a harmonic oscillator with ultrastrong coupling

Li-Tuo Shen·Zhen-Biao Yang·Rong-Xin Chen
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Abstract

We study the Rabi model composed of three qubits coupled to a harmonic oscillator without involving the rotating-wave approximation. We show that the ground state of the three-qubit Rabi model can be analytically treated by using the transformation method, and the transformed ground state agrees well with the exactly numerical simulation under a wide range of qubit-oscillator coupling strengths for different detunings. We use the pairwise entanglement to characterize the ground-state entanglement between any two qubits and show that it has an approximately quadratic dependence on the qubit-oscillator coupling strength. Interestingly, we find that there is no qubit-qubit entanglement for the ground state if the qubit-oscillator coupling strength is large enough.

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Li-Tuo Shen, Zhen-Biao Yang, Rong-Xin Chen. 2013-10-21. Ground state of three qubits coupled to a harmonic oscillator with ultrastrong coupling. https://doi.org/10.1103/physreva.88.045803

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