On-demand control of coherence transfer between interacting qubits surrounded by a dissipative environment
Zhong‐Xiao Man, Yun‐Jie Xia, Nguyen Ba An · Physical Review A · 2014
On-demand measurement-based schemes to control coherence transfer between interacting qubits inside a dissipative environment are considered. The measurements employed are of the types of quantum weak measurement and quantum reversal measurement of which one is carried out at the beginning of the system evolution $t=0$ and the other at a later intended time $t>0.$ The relevant questions are which type of measurement should be performed at $t=0$ and which type at $t>0$, as well as which strength of the second measurement should be chosen in dependence on the strength of the first measurement to optimally achieve a demand? We answer such questions in this work as to meet two concrete demands, namely, to make optimal (i) the transfer of coherence from the $s$th qubit to the $r$th qubit and (ii) the preservation of coherence at the $s$th qubit. Particularly, independent of the coherence degree of the $s$th qubit at $t=0,$ the coherence degree of either the $r$th qubit or the $s$th qubit at any $t>0$ can be made arbitrarily close to the maximum value equal to 1/2, but at the cost of vanishingly reduced success probability. As an application, we discuss the coherence transfer between two qubits of a bipartite system. We also analyze the influence of the controlling schemes for optimal coherence transfer on the degree of entanglement created at $t>0$ between the two qubits.