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Computer Optics

Analysis of the behavior of entanglement parameters for the three-qubit Tavis-Cummings model with multiphoton processes

Alexander R. Bagrov, Башкиров Е. К

Published Dec 1, 2025• 0 citations
Publisher

Abstract

In this paper, we analyze in detail the dynamics of the negativity criterion, fidelity and concurrence fill for the Tavis-Cummings model in which three qubits are in a common single-mode ideal resonator and interact resonantly with the field mode via multiphoton processes. By solving the unsteady Schrödinger equation, we give analytic solutions for genuine entangled Werner- and Greenberger-Horn-Zeilinger states. It is shown that the multiplicity of photon transitions can significantly stabilize the genuine entangled states of both types. Key features in the dynamics pattern of the entanglement parameters are highlighted. We conclude that the negativity criterion is not suitable for describing the dynamics of entanglement of qubits in the case of three-qubit Greenberger-Horn-Zeilinger states. Main advantages of the concurrence fill over the negativity criterion are shown.

DOI
10.18287/2412-6179-co-1679

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In this paper, we analyze in detail the dynamics of the negativity criterion, fidelity and concurrence fill for the Tavis-Cummings model in which three qubits are in a common single-mode ideal resonator and interact resonantly with the field mode via multiphoton processes. By solving the unsteady Schrödinger equation, we give analytic solutions for genuine entangled Werner- and Greenberger-Horn-Zeilinger states. It is shown that the multiplicity of photon transitions can significantly stabilize the genuine entangled states of both types. Key features in the dynamics pattern of the entanglement parameters are highlighted. We conclude that the negativity criterion is not suitable for describing the dynamics of entanglement of qubits in the case of three-qubit Greenberger-Horn-Zeilinger states. Main advantages of the concurrence fill over the negativity criterion are shown.
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Abstract An exact solution for the evolution operator of the multiphoton three-qubit Tavis–Cummings model was found. On this basis, the entanglement dynamics and the phenomenon of entanglement sudden death for entangled initial W-, GHZ-, and GHZ-like qubit states and the thermal state of the resonator were studied by means of pairwise negativity and fidelity. The results of entanglement parameters calculations showed that in the nonlinear multiphoton processes, the atomic entanglement is stronger than in the linear one-photon process. We also obtained that the so-called sudden death phenomenon occurs only for some kind of initial qubit states and some thermal noise intensities, i.e. the phenomenon is sensitive to the initial conditions. The length of the time interval for the zero entanglement is dependent on not only the initial qubit states but also the photon transition multiple. We also showed that for large values of the multiple, only one W-type initial state and one GHZ-like initial state are the long-lived and maximally persistent and robust states.
The article studies the dynamics of pairwise entanglement of three qubits, two of which are trapped in a resonator and interact with a single-mode ideal resonator through single-photon transitions, and the third qubit is outside the resonator. This takes into account the dipole-dipole coupling between the isolated qubit and the qubit in the resonator. We have found a solution to the quantum nonstationary Schrodinger equation for the total wave function of the system for the initial separable and biseparable states of qubits and the thermal initial state of the resonator field. Using these solutions, the criterion of entanglement of qubit pairs - negativity is calculated. The results of numerical simulation of the negativity criterion have shown that the including of a small dipole-dipole coupling between an isolated and one of the trapped qubits can lead to significant entanglement of qubit pairs for all initial states. There is a transition of entanglement from one pair of atoms to other pairs of atoms during the evolution of the system. It is also shown that for some separable and biseparable states, the dipole-dipole interaction can suppress the effect of sudden death of entanglement.
In this paper, we investigated the dynamics of systems of two and three identical qubits interacting resonantly with a selected mode of a thermal field of a lossless resonator. We found solutions of the quantum time-dependent Liouville equation for various three- and two-qubit entangled states of qubits. Based on these solutions, we calculated the criterion of the qubit entanglement — fidelity. The results of numerical calculations of the fidelity showed that increasing the average number of photons in a mode leads to a decrease in the maximum degree of entanglement. It is shown that the two-qubit entangled state is more stable with respect to external noise than the three-qubit entangled Greenberger — Horne — Zeilinger states (GHZ). Moreover, a genuine entangled GHZ-state is more stable to noise than a GHZ-like entangled state.
In this paper, a three-qubit Tavis-Cummings model with two independent lossless single-mode resonators is considered. It is assumed that the initial states of the resonator fields are thermal fields and the qubits are in genuine entangled W- and GHZ-type states. For the model under study and the specified initial states of the resonator fields and qubits, we have exactly solved the quantum Liouville equation for the full density matrix. The full density matrix was used to calculate the entanglement parameters - negativity and fidelity. The computer simulation results showed that in the investigated model, the entanglement for all initial qubit states breaks down rapidly with increasing intensity of the thermal fields of the resonators compared to the previously investigated three-qubit models. Moreover, a sudden death of entanglement is observed even for vacuum resonator fields.
This paper presents an exact solution for the evolution operator of the three-qubit Jaynes-Cummings model. It is assumed that the qubits are prepared at the initial moment of time in genuine entangled W- and GHZ-type states, and the field is in a vacuum state. Based on the exact solution, wave functions, density matrix elements, and qubit entanglement parameters - the pairwise negativity criterion and the fidelity - were calculated. Using the entanglement parameters, the full analysis of the qubit entanglement dynamics was performed.