Resource-efficient linear-optical quantum router

Abstract

All-linear-optical scheme for fully featured quantum router is presented. This device directs the signal photonic qubit according to the state of one control photonic qubit. In the introduction we formulate the list of requirements imposed on a fully quantum router. Then we describe our proposal showing the exact principle of operation on a linear-optical scheme. Subsequently we provide generalization of the scheme in order to optimize the success probability by means of a tunable controlled-phase gate. At the end, we show how one can modify the device to route multiple signal qubits using the same control qubit.Comment: 7 pages, 6 figure

Cascaded Multi-Level Linear-Optical Quantum Router

“…Now we extend the protocol described in Re. [41] to explain the cascaded quantum router. As shown in Fig.…”

“…1, a signal qubit enters the router through the signal input port while the control qubit enters the router using the port of control input [41]. In their protocol, they exploit the generalized c-phase gate [46,47], quantum nondemolition detector and programmable-phase gate to complete the quantum router.…”

“…[41] to implement the multilevel quantum router. We only considered the c-phase gate with a fixed phase shift of ϕ = π .…”

“…Signal qubit is routed into a coherent superposition of two output modes S 1 , S 2 , depending on the state of the control qubit Fig. 2 The success probability of the one-level quantum router [41], which is altered with θ . The total success probability of P (1) succ can reach the maximum of 1/8 when θ = 0, and can reach the minimum of 1/24 when θ = π 2 From Fig.…”

“…1 Basic model of the quantum router [41]. Signal qubit is routed into a coherent superposition of two output modes S 1 , S 2 , depending on the state of the control qubit Fig.…”