Transfer ofd-level quantum states through spin chains by random swapping

Abstract

We generalize an already proposed protocol for quantum state transfer to spin chains of arbitrary spin. An arbitrary unknown d− level state is transferred through a chain with rather good fidelity by the natural dynamics of the chain. We compare the performance of this protocol for various values of d. A by-product of our study is a much simpler method for picking up the state at the destination as compared with the one proposed previously. We also discuss entanglement distribution through such chains and show that the quality of entanglement transition increases with the number of levels d.

Quantum state transfer along a ring with time-reversal asymmetry

“…Based on cavity quantum electrodynamics a scheme is to transfer the state of a qubit from a cavity-atom system to another one through an optical fiber connecting the two cavities. Using the spin chain as a channel many schemes are reported, such as, QST along a one dimensional unmodulated spin chain [1], perfect QST achieved by modulating the coupling strength [3,5,[8][9][10][11][12], QST without initialization [13,14], optimizing basis [15,16] and generalizing to the high spin QST [17][18][19]. Other schemes, such as, transferring single-mode photon state through a coupled-cavity array, are also reported.…”

Entanglement enhancement for two spins assisted by two phase kicks

“…Other aspects of entanglement in higher dimensional systems, like entanglement concentration for two qudits in [8], and its experimental implementation for two qutrits [9] were reported. It was also shown in [10] that the quality of entanglement transfer in spin chains actually increases with the dimension of the spin.…”

Transfer of an arbitrary photon state along a cavity array without initialization

“…For a chain of any length perfect QST can be achieved by modulating the coupling strengths between adjacent spins [22][23][24][25]. Other schemes are also discussed, such as only tuning the coupling strengths to get high fidelity QST [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], QST without initialization [41,42], optimizing basis [43,44], using special external potential [45][46][47] or measurement [48] and generalizing to high spin QST [49][50][51][52]. A number-theoretic relation between QST and the length of a one-dimension spin chain is found in [53].…”