Ground state of a resonant two-qubit Rabi model in the ultrastrong coupling regime

Abstract

We consider 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 provide good agreement with the exact numerical ground state for a range of coupling strength in the ultrastrong regime. In addition, we indicate how the accuracy of the approximation can be further improved by using perturbation theory. We also examine the ground state entanglement between the two qubits. By calculating the negativity, we quantify the degree of entanglement as a function of coupling strength.

5 pages, 2 figures

References in corpus (12)

• Beyond the Jaynes-Cummings model: circuit QED in the ultrastrong coupling regime
• Observation of the Bloch-Siegert Shift in a Qubit-Oscillator System in the Ultrastrong Coupling Regime
• Deep Strong Coupling Regime of the Jaynes-Cummings model
• Ultra-Strong Light-Matter Coupling Regime with Polariton Dots
• Photon Blockade in the Ultrastrong Coupling Regime
• Generalized rotating-wave approximation for arbitrarily large coupling
• Superradiance transition in a system with a single qubit and a single oscillator
• Spontaneous Conversion from Virtual to Real Photons in the Ultrastrong Coupling Regime
• Qubit-oscillator system: An analytical treatment of the ultra-strong coupling regime
• Variational study of a two-level system coupled to a harmonic oscillator in a ultrastrong coupling regime
• Universal Critical Behavior in the Dicke Model
• Vacuum Rabi oscillation induced by virtual photons in the ultrastrong coupling regime

Cited by in corpus (12)

• Generalized rotating-wave approximation to the two-qubit and cavity coupling system
• Quantum phase transitions for an integrable quantum Rabi-like model with two interacting qubits
• Variational generalized rotating-wave approximation in the two-qubit quantum Rabi model
• Searching for structure beyond parity in the two-qubit Dicke model
• Application of polaron picture in the two-qubit quantum Rabi model
• Ground state of the asymmetric Rabi model in the ultrastrong coupling regime
• Thermodynamic Limit in the Two-qubit Quantum Rabi Model with Spin-Spin Coupling
• Ground state of three qubits coupled to a harmonic oscillator with ultrastrong coupling
• Adiabatic approximation for three qubits ultrastrongly coupled to a harmonic oscillator
• Dissipative dynamics of atom-field entanglement in the ultrastrong-coupling regime
• GHZ-like states in the Qubit-Qudit Rabi Model
• Study of the spin kitten states in a strongly coupled spin-oscillator system