Abstract
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.
Highlights
Photons remain a promising vehicle for the development of next-generation quantum technology [1, 2]
We perform multi-qubit quantum logic on these states and study their entanglement. We implemented this scheme on a reconfigurable, silicon photonic device to generate a wide range of two-qubit states
The internal RHOM phases were set to p 2, such that the produced photon-pairs emerged deterministically split, one in each output waveguide, and in a state symmetrical between signal and idler photons. fb allows us to control the balance of photon-pair emission between the two RHOM structures, and so to control the entanglement present in the two-qubit output state
Summary
Photons remain a promising vehicle for the development of next-generation quantum technology [1, 2]. Several important quantum optical functionalities have already been shown with high performance in silicon. The integration of entangled qubit sources with entangling quantum logic, together on a common platform, is an important step. We perform multi-qubit quantum logic on these states and study their entanglement. We implemented this scheme on a reconfigurable, silicon photonic device to generate a wide range of two-qubit states. We integrated this source with arbitrary state preparation, a switchable two-qubit gate, and an interferometer for tomographic analysis. We followed this with an exploration of the on-chip quantum logic, with the switchable two-qubit gate in both entangling (cz) and non-entangling (I) configurations, and using the purity (P) [41], the CHSH parameter (S) [42] and the Schmidt number (K ) [43] as diagnostic metrics
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