Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1203.0423 · Physics Letters A

Adiabatic approximation in the ultrastrong-coupling regime of an oscillator and two qubits

Ping Hsing Yang, Ping Zou, Zhi‐Ming Zhang

Published Sep 10, 2012• 4 citations
arXivHTMLPDF
DOI
10.1016/j.physleta.2012.09.005

Related papers

Qubit-oscillator systems in the ultrastrong-coupling regime and their potential for preparing nonclassical states

Franco Nori, Sahel Ashhab

Bulletin of the American Physical Society•Mar 22, 2011•0 citations

Superconducting qubit–oscillator circuit beyond the ultrastrong-coupling regime

Fumiki Yoshihara, Tomoko Fuse, Sahel Ashhab +3 more

arXiv:1602.00415•Nature Physics•Oct 10, 2016•656 citations

Adiabatic approximation for three qubits ultrastrongly coupled to a harmonic oscillator

Li-Tuo Shen, Rongxin Chen, Huai‐Zhi Wu +1 more

We study the system involving mutual interaction between three qubits and an oscillator within the ultrastrong coupling regime. We apply the adiabatic approximation approach to explore two extreme regimes: (i) the oscillator's frequency is far larger than each qubit's frequency and (ii) the qubit's frequency is far larger than the oscillator's frequency, and analyze the energy-level spectrum and the ground-state property of the qubit-oscillator system under the conditions of various system parameters. For the energy-level spectrum, we concentrate on studying the degeneracy in low-energy levels. For the ground state, we focus on its nonclassical properties that are necessary for preparing the nonclassical states. We show that the minimum qubit-oscillator coupling strength needed for generating the nonclassical states of the Schr\"odinger-cat type in the oscillator is just one half of that in the Rabi model. We find that the qubit-qubit entanglement in the ground state vanishes if the qubit-oscillator coupling strength is strong enough, for which the entropy of three qubits remains larger than 1. We also observe the phase-transition-like behavior in the regime where the qubit's frequency is far larger than the oscillator's frequency.

arXiv:1311.0982•Physical Review A•Feb 10, 2014•4 citations

Two kinds of quantum adiabatic approximation

Ming-Yong Ye, Xiang-Fa Zhou, Yong-Sheng Zhang +1 more

arXiv:0801.0521•Physics Letters A•Mar 28, 2007•11 citations

Entanglement dynamics of the ultrastrong-coupling three-qubit Dicke model

Lijun Mao, Yanxia Liu, Yunbo Zhang

We give an analytical description of the dynamics of the three-qubit Dicke model using the adiabatic approximation in the parameter regime where the qubit transition frequencies are far off-resonance with the field frequency and the interaction strengths reach the ultrastrong-coupling regimes. Qualitative differences arise upon comparison to single- and two-qubit systems. Simple analytic formulas show that three revival sequences produce a three-frequency beat note in the time evolution of the population. We find an explicit way to estimate the dynamics for qubit-field and qubit-qubit entanglement inside the three-qubit system in the ultrastrong-coupling regime, and the resistance to sudden death proves that the entanglement in the Greenberger-Horne-Zeilinger state is more robust than that in the $W$ state.

arXiv:1512.06387•Physical Review A•May 3, 2016•14 citations

Ground state of a resonant two-qubit cavity system in the ultrastrong-coupling regime

Kelvin M. C. Lee, C. K. Law

We examine a generalized Rabi model formed by two identical qubits interacting with a common oscillator mode. In the near-resonance configuration where the oscillator frequency is close to the transition frequency of the qubit, we determine the ground state of the model approximately by using a variational method and a transformation method. Both methods are shown to approximate the ground state accurately for a range of coupling strengths in the ultrastrong-coupling regime. In addition, the accuracy of the approximation can be further improved by using perturbation theory. We also characterize the ground-state entanglement between the two qubits by calculating the negativity.

arXiv:1303.3367•Physical Review A•Jul 8, 2013•21 citations
We study the system involving mutual interaction between three qubits and an oscillator within the ultrastrong coupling regime. We apply the adiabatic approximation approach to explore two extreme regimes: (i) the oscillator's frequency is far larger than each qubit's frequency and (ii) the qubit's frequency is far larger than the oscillator's frequency, and analyze the energy-level spectrum and the ground-state property of the qubit-oscillator system under the conditions of various system parameters. For the energy-level spectrum, we concentrate on studying the degeneracy in low-energy levels. For the ground state, we focus on its nonclassical properties that are necessary for preparing the nonclassical states. We show that the minimum qubit-oscillator coupling strength needed for generating the nonclassical states of the Schr\"odinger-cat type in the oscillator is just one half of that in the Rabi model. We find that the qubit-qubit entanglement in the ground state vanishes if the qubit-oscillator coupling strength is strong enough, for which the entropy of three qubits remains larger than 1. We also observe the phase-transition-like behavior in the regime where the qubit's frequency is far larger than the oscillator's frequency.
We give an analytical description of the dynamics of the three-qubit Dicke model using the adiabatic approximation in the parameter regime where the qubit transition frequencies are far off-resonance with the field frequency and the interaction strengths reach the ultrastrong-coupling regimes. Qualitative differences arise upon comparison to single- and two-qubit systems. Simple analytic formulas show that three revival sequences produce a three-frequency beat note in the time evolution of the population. We find an explicit way to estimate the dynamics for qubit-field and qubit-qubit entanglement inside the three-qubit system in the ultrastrong-coupling regime, and the resistance to sudden death proves that the entanglement in the Greenberger-Horne-Zeilinger state is more robust than that in the WWW state.
We examine a generalized Rabi model formed by two identical qubits interacting with a common oscillator mode. In the near-resonance configuration where the oscillator frequency is close to the transition frequency of the qubit, we determine the ground state of the model approximately by using a variational method and a transformation method. Both methods are shown to approximate the ground state accurately for a range of coupling strengths in the ultrastrong-coupling regime. In addition, the accuracy of the approximation can be further improved by using perturbation theory. We also characterize the ground-state entanglement between the two qubits by calculating the negativity.