We investigate the state or entanglement transfer through a two-dimensional spin network. We show that for state transfer, better fidelity can be gained along the diagonal direction but for entanglement transfer, when...We investigate the state or entanglement transfer through a two-dimensional spin network. We show that for state transfer, better fidelity can be gained along the diagonal direction but for entanglement transfer, when the initial entanglement is created along the boundary, the concurrence is more inclined to propagate along the boundary. This behavior is produced by quantum mechanical interference and the communication quality depends on the precise size of the network. For some number of sites, the fidelity in a two-dimensional channel is higher than one-dimensional case. This is an important result for realizing quantum communication through high dimension spin chain networks.展开更多
Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state 丨i 丨of the chain is swapped into the state 丨N - i丨 within a time evolution interval r. Such a phenomenon is an i...Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state 丨i 丨of the chain is swapped into the state 丨N - i丨 within a time evolution interval r. Such a phenomenon is an interesting way of transfering entanglement. An expressions for the perfect mirroring of a single qubit contained in a spin chain were proposed in the past. We exploit such an expressions for calculating the evolution times in chains of both two and three spins. In the case of a chain of two qubits, we derive conditions under which the associated four Bell states diagonalize the Hamiltonian. It is found that for the two Bell states 丨Ф＋） and 丨Ф-）, perfect mirroring does not occur （i.e. entanglement is not preserved under swapping）. On the other hand, perfect single qubit mirror effect （entanglement preservation） indeed occurs for the other two Bell states 丨ψ＋） and 丨ψ-） which are mapped into 丨Ф＋） and 丨Ф-） respectively. For the case of a chain of three qubits, the effects of a perfect single qubit mirroring on a set of four maximally entangled three qubit states ψl, ψ2, X1, and X2are studied. Due to the fact that quantum mirroring preserves maximal entanglement, the states ψ1 and ψ2 are not altered. However, quantum mirroring changes the states X1 and X2 only if we apply perfect quantum state mirroring in the site a = 1 of the three qubits spin chain. The above constrains the preservation of maximal entanglement under qubit mirroring of such a state. Due to the fact that swapping has already been experimentally tested, a posible, experimental implementations of single qubit mirroring is possible.展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos. 11005099, 60677044the Fundamental Research Funds for the Central Universities under Grant No. 201013037
文摘We investigate the state or entanglement transfer through a two-dimensional spin network. We show that for state transfer, better fidelity can be gained along the diagonal direction but for entanglement transfer, when the initial entanglement is created along the boundary, the concurrence is more inclined to propagate along the boundary. This behavior is produced by quantum mechanical interference and the communication quality depends on the precise size of the network. For some number of sites, the fidelity in a two-dimensional channel is higher than one-dimensional case. This is an important result for realizing quantum communication through high dimension spin chain networks.
文摘Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state 丨i 丨of the chain is swapped into the state 丨N - i丨 within a time evolution interval r. Such a phenomenon is an interesting way of transfering entanglement. An expressions for the perfect mirroring of a single qubit contained in a spin chain were proposed in the past. We exploit such an expressions for calculating the evolution times in chains of both two and three spins. In the case of a chain of two qubits, we derive conditions under which the associated four Bell states diagonalize the Hamiltonian. It is found that for the two Bell states 丨Ф＋） and 丨Ф-）, perfect mirroring does not occur （i.e. entanglement is not preserved under swapping）. On the other hand, perfect single qubit mirror effect （entanglement preservation） indeed occurs for the other two Bell states 丨ψ＋） and 丨ψ-） which are mapped into 丨Ф＋） and 丨Ф-） respectively. For the case of a chain of three qubits, the effects of a perfect single qubit mirroring on a set of four maximally entangled three qubit states ψl, ψ2, X1, and X2are studied. Due to the fact that quantum mirroring preserves maximal entanglement, the states ψ1 and ψ2 are not altered. However, quantum mirroring changes the states X1 and X2 only if we apply perfect quantum state mirroring in the site a = 1 of the three qubits spin chain. The above constrains the preservation of maximal entanglement under qubit mirroring of such a state. Due to the fact that swapping has already been experimentally tested, a posible, experimental implementations of single qubit mirroring is possible.
