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arXiv:1508.03214 · Optica

Chip-to-chip quantum photonic interconnect by path-polarization interconversion

Jianwei Wang, Damien Bonneau, Matteo Villa, Joshua W. Silverstone, Raffaele Santagati, Shigehito Miki, Taro Yamashita, Mikio Fujiwara, Masahide Sasaki, Hirotaka Terai, Michael G. Tanner, Chandra M. Natarajan, Robert H. Hadfield, Jeremy L. O’Brien, Mark G. Thompson

Published Apr 11, 2016• 160 citations
arXivHTMLPDF

Abstract

Integrated photonics has enabled much progress towards quantum technologies. Many applications, including quantum communication, sensing, and distributed and cloud quantum computing, will require coherent photonic interconnection between separate chip-based sub-systems. Large-scale quantum computing systems and architectures may ultimately require quantum interconnects to enable scaling beyond the limits of a single wafer and towards "multi-chip" systems. However, coherently interconnecting separate chips is challenging due to the fragility of these quantum states and the demanding challenges of transmitting photons in at least two media within a single coherent system. Distribution and manipulation of qubit entanglement between multiple devices is one of the most stringent requirements of the interconnected system. Here, we report a quantum photonic interconnect demonstrating high-fidelity entanglement distribution and manipulation between two separate chips, implemented using state-of-the-art silicon photonics. Path-entangled states are generated and manipulated on-chip, and distributed between the chips by interconverting between path-encoding and polarisation-encoding. We use integrated state analysers to confirm a Bell-type violation of $S$=2.638+-0.039 between two chips. With improvements in loss, this quantum interconnect will provide new levels of flexible systems and architectures for quantum technologies.

DOI
10.1364/optica.3.000407

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Integrated photonics has enabled much progress towards quantum technologies. Many applications, including quantum communication, sensing, and distributed and cloud quantum computing, will require coherent photonic interconnection between separate chip-based sub-systems. Large-scale quantum computing systems and architectures may ultimately require quantum interconnects to enable scaling beyond the limits of a single wafer and towards "multi-chip" systems. However, coherently interconnecting separate chips is challenging due to the fragility of these quantum states and the demanding challenges of transmitting photons in at least two media within a single coherent system. Distribution and manipulation of qubit entanglement between multiple devices is one of the most stringent requirements of the interconnected system. Here, we report a quantum photonic interconnect demonstrating high-fidelity entanglement distribution and manipulation between two separate chips, implemented using state-of-the-art silicon photonics. Path-entangled states are generated and manipulated on-chip, and distributed between the chips by interconverting between path-encoding and polarisation-encoding. We use integrated state analysers to confirm a Bell-type violation of SSS=2.638+-0.039 between two chips. With improvements in loss, this quantum interconnect will provide new levels of flexible systems and architectures for quantum technologies.
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Quantum networks provide a novel framework for quantum information processing, significantly improving system capacity through the interconnection of modular quantum nodes. Beyond the capability to distribute quantum states, the ability to remotely control quantum gates is a pivotal step for quantum networks. Here, we implement high-fidelity quantum controlled-not (cnot) gate teleportation with high-dimensional path encoded silicon photonic integrated circuits. Based on on-chip generation of the path-entangled quantum state, cnot gate operation, and chip-to-chip quantum photonic interconnect, the cnot gate is teleported between two remote quantum nodes connected by the single-mode optical fiber. Equip with 5 m (1 km)-long interconnecting fiber, quantum gate teleportation is verified by entangling remote qubits with 95.69%±1.19% (94.07%±1.54%) average fidelity and gate tomography with 94.81%±0.81% (93.04%±1.09%) fidelity. These results advance the realization of large-scale and practical quantum networks with photonic integrated circuits.