Robust and efficient transport of two-qubit entanglement via disordered spin chains

Abstract

We investigate how robust is the modified XX spin-1/2 chain of [R. G. Rigolin, Phys. Lett. A 382, 2586 (2018)] in transmitting entanglement when several types of disorder and noise are present. First, we consider how deviations about the optimal settings that lead to almost perfect transmission of a maximally entangled two-qubit state affect the entanglement reaching the other side of the chain. Those deviations are modeled by static, dynamic, and fluctuating disorder. We then study how spurious or undesired interactions and external magnetic fields diminish the entanglement transmitted through the chain. For chains of the order of hundreds of qubits, we show for all types of disorder and noise here studied that the system is not appreciably affected when we have weak disorder (deviations of less than 1% about the optimal settings) and that for moderate disorder it still beats the standard and ordered XX model when deployed to accomplish the same task. IntroductionAn important tool in the practical implementation of quantum computation and communication tasks is the reliable transmission of quantum states from one location to another [1]. Quantum information, or equivalently a quantum state, can be sent from one party (Alice) to another (Bob) in at least three ways, namely, via direct transmission, via the quantum teleportation protocol [2], and via spin chains [3]. This last strategy, where Alice and Bob are connected by a spin chain through which they can send quantum states to each

Two-Excitation Routing via Linear Quantum Channels

“…In Refs. [ 17 , 18 ] each spin of the sender (receiver) block is coupled to the edges of the 1D quantum wire allowing for the transfer of a Bell state when operating in the single-excitation subspace. A similar geometry is adopted in Refs.…”

“…While a great amount of work has been devoted to the routing of the quantum state of a single qubit [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], where the fidelity of the transfer protocol can be expressed in terms of the transition amplitude of a single excitation between a sender and a receiver location [ 12 ], the routing of a multiple qubit state is a far less investigated scenario. Although several protocols have been proposed both for two-qubit and multi-partite entangled quantum state transfer [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], their extension to a routing configuration on an arbitrary network is not straightforward. One reason being that almost all the proposed protocols rely on the quantum channel possessing mirror-symmetry, which, allowing for multiple receivers at arbitrary positions, is difficult to attain: in Ref.…”

Two-Excitation Routing via Linear Quantum Channels

“…In Refs. [18,19] each spin of the sender (receiver) block is coupled to the edges of the 1D quantum wire allowing for the transfer of a Bell state when operating in the single-excitation subspace. A similar geometry is adopted in Refs.…”

“…While a great amount of work has been devoted to the routing of the quantum state of a single qubit [4][5][6][7][8][9][10][11][12], where the fidelity of the transfer protocol can be expressed in terms of the transition amplitude of a single excitation between a sender and a receiver location [13], the routing of a multiple qubit state is a far less investigated scenario. Although several protocols have been proposed both for two-qubit and multi-partite entangled quantum state transfer [14][15][16][17][18][19][20][21][22][23], their extension to a routing configuration on an arbitrary network is not straightforward. One reason being that almost all the proposed protocols rely on the quantum channel possessing mirror-symmetry, which, allowing for multiple receivers at arbitrary positions, is difficult to attain: in Ref.…”

Multipartite entanglement transfer in spin chains

“…A prototypical quantum channel is embodied by a quantum spin- 1 2 chain, with the sender and receiver located at its edges [13,14]. Whereas, the transfer of twoqubit entanglement has been extensively investigated via spin chain [15,16,17,18,19], multipartite entanglement transfer between the edges of a spin chain has not yet been addressed. In this paper, we build on the perturbatively perfect excitations transfer scheme [20] which has already been successfully adopted for one-and two-qubit quantum state transfer protocols [21,22,23].…”