Quantum repeater and system and method for creating extended entanglements

摘要

A method is provided of creating an end-to-end entanglement (87) between qubits in first and second end nodes (81, 82) of a chain of optically-coupled nodes whose intermediate nodes (80) are quantum repeaters. Local entanglements (85) are created on an on-going basis between qubits in neighboring pairs in the chain through interaction of the qubits with light fields transmitted between the nodes. The quantum repeaters (80) are cyclically operated with their top-level operating cycles being synchronized. Once every top-level operating cycle, each repeater (80) initiates a merging of two entanglements involving respective repeater qubits that are at least expected to be entangled with qubits in nodes disposed in opposite directions along the chain from the repeater. A quantum repeater (80) adapted for implementing this method is also provided.

主权项

1. A quantum repeater optically couplable to left and right neighbour nodes through local-link optical channels; the repeater comprising:
quantum physical hardware providing left-side and right-side repeater portions (L, R) respectively arranged to support left-side and right-side qubits for entanglement with qubits in the left and right neighbour nodes respectively by light fields transmitted over the local-link channels thereby to form respective local link entanglements, herein “LLE”s; the quantum physical hardware being operable to merge two entanglements respectively involving a left-side and a right-side qubit, by locally operating on these qubits; left and right LLE control units for controlling the quantum physical hardware to effect on-going creation of left and right LLEs in cooperation with the left and right neighbour nodes; and a top-level control arrangement operative to control top-level cyclic operation of the repeater in synchronism with its neighbour nodes, the top-level control arrangement being arranged once every top-level operating cycle to initiate merging of entanglements respectively involving a left-side and a right-side qubit when these qubits are at least expected to be entangled leftwards and rightwards respectively.