CEA-Leti is building a quantum-photonics platform to develop next-generation technologies for industries that require ultra-secure data transmission. Quantum technology promises to provide extremely safe data encryption required by the finance, health care, energy, telecommunications, defence and other sectors.

“We read about breaches of standard cryptography protocols almost daily, with major financial-loss and security-risk implications and the threat to critical infrastructure, such as power-supply systems,” said Ségolène Olivier, R&D project leader at CEA-Leti. “With the future advent of quantum computers, the risk will drastically increase as current encryption algorithms will not be safe anymore. Quantum cryptography is the solution to this problem as it is not vulnerable to computing power.”

Funded by Carnot, a French multidisciplinary R&D network, the project will build on CEA-Leti’s silicon-photonics platform complemented with new quantum characterisation equipment for designing, processing and testing quantum-photonic integrated components and circuits. The institute uses photons to build quantum bits, or qubits, for quantum communication.

The three-year project will fabricate silicon-photonics circuits that generate single photons, manipulate those photons with linear optical components such as slow and rapid phase shifters and detect them with superconducting nanowire single-photon detectors (SNSPD). The project will build demonstrators for transmitting and receiving information in a quantum-based system to deliver quantum-technology’s promise for ultra-secure cryptography. For example, the demonstrators will realise an integrated qubit transmitter, as a circuit generating single photons and entangling them. An integrated qubit receiver will be built to detect the photons. In addition, the CEA-Leti team will focus on integrating the qubit transmitter and the qubit receiver on one unique platform to address also quantum computing applications.

Noting that a quantum system based on single-photon qubits must ensure there is minimal propagation loss of photons to be reliable, Olivier said CEA-Leti’s silicon photonics platform has achieved a world-record of low-loss silicon and ultralow-loss silicon-nitride waveguides: “Propagation losses in waveguides directly impact the data rate and reach of quantum communications links, that’s why it is so important to build ultralow-loss components and circuits.” 

[Image: Michael Dziedzic for Unsplash]