From quantum multiplexing to high-performance quantum networking

Abstract

Our objective was to design a quantum repeater capable of achieving one million entangled pairs per second over a distance of 1000km. We failed, but not by much. In this letter we will describe the series of developments that permitted us to approach our goal. We will describe a mechanism that permits the creation of entanglement between two qubits, connected by fibre, with probability arbitrarily close to one and in constant time. This mechanism may be extended to ensure that the entanglement has high fidelity without compromising these properties. Finally, we describe how this may be used to construct a quantum repeater that is capable of creating a linear quantum network connecting two distant qubits with high fidelity. The creation rate is shown to be a function of the maximum distance between two adjacent quantum repeaters.

Secure Long-Distance Quantum Communication over Optical Fiber Quantum Channels

“…The hybrid quantum repeater uses atomic-qubit entanglement and optical coherent state communication (Munro et al, 2010). In practice, the base stations of the quantum repeaters are connected by optical fibers, the entangled quantum states are sent through these fibers , (Sangouard et al, 2009).…”

“…The quantum transformations at the receiver side of teleportation require classical inputs, since the quantum teleportation protocol uses them to recover the unknown quantum state from the entangled quantum state (Munro et al, 2010), , (Sangouard et al, 2009). In the sharing process, the sender base station entangles the quantum state with another separate physical qubit, and then it is multiplexed into the quantum channel (Van Meter et al, 2009).…”

“…At the receiver's side, the multiplexed pulses are demultiplexed, and the receiver entangles each pulse with a free quantum state. If the entangling operation is successful, then the sender and the receiver share an EPR state (Duan et al, 2001), (Munro et al, 2010), (World Wide Science, 2011).…”

“…As follows, in the next step, the created entanglement has to be purified (Bernardes et al, 2010), (Munro et al, 2010), (Van Meter et al, 2009). The purification is an error-correcting scheme, and it uses local quantum operations only -hence these operations can be realized in the separated base stations locally (Van Meter et al, 2009).…”

Analysis of quantum network coding for realistic repeater networks

“…In order to solve this problem, quantum repeaters have been proposed [11] and many of the components have been experimentally demonstrated [12,13]. A quantum repeater has multiple important roles: to create and share physical en- * satoh@sfc.wide.ad.jp † kaori@sfc.wide.ad.jp; Current address: HAL Laboratories ‡ kurosagi@sfc.wide.ad.jp § rdv@sfc.wide.ad.jp tanglement pairs (Bell pairs) between nearest neighbors over short distances, to perform purification of Bell pairs, and to create one long Bell pair by connecting two entangled pairs using entanglement swapping [11,[14][15][16][17][18][19]. Long range, complex quantum networks can be realized by arranging a number of quantum repeaters and links.…”