Decoherence and Entanglement Dynamics of Coupled Qubits

Abstract

We study the entanglement dynamics and relaxation properties of a system of two interacting qubits in the two cases (I) two independent bosonic baths and (II) one common bath, at temperature T. The entanglement dynamics is studied in terms of the concurrence C (t) between the two spins and of the von Neumann entropy S(t) with respect to the bath, as a function of time. We prove that the system does thermalize. In the case (II) of a single bath, the existence of a decoherence-free (DFS) subspace makes entanglement dynamics very rich. We show that when the system is initially in a state with a component in the DFS the relaxation time is surprisingly long, showing the existence of semi-decoherence free subspaces. The equilibrium state in this case is not the Gibbs state. The entanglement dynamics for the single bath case is also studied as a function of temperature, coupling strength with the environment and strength of tunneling coupling. The case of the mixed state is finally shown and discussed.

improved version with all the details and study in function of temperature, coupling strengths and the study of the mixed state case

References in corpus (10)

• Preparation of Entangled States by Quantum Markov Processes
• A no-go theorem for a two-dimensional self-correcting quantum memory based on stabilizer codes
• Topological order in a 3D toric code at finite temperature
• On thermalization in Kitaev's 2D model
• Entangling oscillators through environment noise
• Dynamics of nonequilibrium thermal entanglement
• A statistical mechanics view on Kitaev's proposal for quantum memories
• Toric-boson model: Toward a topological quantum memory at finite temperature
• Cooling atoms into entangled states
• Entanglement between qubits induced by a common environment with a gap

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• A dissipative environment may improve the quantum annealing performances of the ferromagnetic p-spin model
• Decoherence times of universal two-qubit gates in the presence of broad-band noise
• Dephasing-assisted entanglement in a system of strongly coupled qubits
• Optimal encoding of two dissipative interacting qubits