N. A. Tashkeev | Searcharxiv

arXiv2025

Restoring of quantum state transferred along XY-spin chain and entanglement evolution

We propose a protocol restoring the state transferred along the spin chain governed by the XY-Hamiltonian. Such dynamics does not preserve the excitation number and leads to mixing multiple-quantum coherence matrices of orders having the same parities. Depending on the initial state, this results in generating ether all possible or only even-order multiple-quantum coherence matrices. Restoring is established via the special unitary transformation applied to the receiver side of the chain (extended receiver). An example of restoring $\pm1$ and $\pm 2$-order coherence matrices in two-qubit state transfer is considered. Entanglement transfer in such process is also studied and possibility of its amplification is demonstrated.

quant-ph↗

arXiv2023

Remote restoring of $(0,1)$-excitation states and concurrence scaling

We study the long distance (0,1)-excitation state restoring in the linear open chain governed by the XX-Hamiltonian. We show that restoring the 1-order coherence matrix results in restoring the 1-excitation block of the 0-order coherence matrix, so that only one 0-excitation element of the density matrix remain unrestored. Such restoring also scales the concurrence between any two qubits of the transferred state, the scaling factor is defined by the Hamiltonian and doesn't depend on the initial sender's state. Sender-Receiver entanglement is also studied via the PPT criterion.

quant-ph↗