1 research outputs found
Creation of Two-Particle Entanglement in Open Macroscopic Quantum Systems
We consider an open quantum system of N not directly interacting spins
(qubits) in contact with both local and collective thermal environments. The
qubit-environment interactions are energy conserving. We trace out the
variables of the thermal environments and N-2 qubits to obtain the
time-dependent reduced density matrix for two arbitrary qubits. We numerically
simulate the reduced dynamics and the creation of entanglement (concurrence) as
a function of the parameters of the thermal environments and the number of
qubits, N. Our results demonstrate that the two-qubit entanglement generally
decreases as N increases. We show analytically that in the limit N tending to
infinity, no entanglement can be created. This indicates that collective
thermal environments cannot create two-qubit entanglement when many qubits are
located within a region of the size of the environment coherence length. We
discuss possible applications of our approach to the development of a new
quantum characterization of noisy environments