Silicon photonic processor of two-qubit entangling quantum logic
R Santagati, J W Silverstone, M J Strain, M Sorel, S Miki, T Yamashita, M Fujiwara, M Sasaki, H Terai, M G Tanner, C M Natarajan, R H Hadfield, J L O’Brien, M G Thompson · Journal of Optics · 2017
Entanglement is a fundamental property of quantum mechanics, and is a primary resource in quantum information systems. Its manipulation remains a central challenge in the development of quantum technology. In this work, we demonstrate a device which can generate, manipulate, and analyse two-qubit entangled states, using miniature and mass-manufacturable silicon photonics. By combining four photon-pair sources with a reconfigurable six-mode interferometer, embedding a switchable entangling gate, we generate two-qubit entangled states, manipulate their entanglement, and analyse them, all in the same silicon chip. Using quantum state tomography, we show how our source can produce a range of entangled and separable states, and how our switchable controlled-Z gate operates on them, entangling them or making them separable depending on its configuration.