Canadian quantum computing startup Photonic Inc. reported last week that the company demonstrated entanglement between two modules at telecom wavelengths, checking off the first goal in an extended collaboration with Microsoft. While many architectures have shown entanglement within modules, Photonic's demonstration achieved distributed entanglement between silicon spin qubits housed in separate cryostats, separated by 40 m of fiber optic cable. The demonstration is a step toward scalable entanglement distribution, a key enabler of quantum computing, said Photonic founder and chief quantum officer Stephanie Simmons.

More broadly, the company said, the demonstration represents a key milestone on the road toward large-scale quantum adoption.

According to a blog post from Microsoft, Photonic’s “T-center” quantum architecture combines the information storage and information processing capabilities of silicon spin qubits with the information transmission capabilities of photons in a spin-photon interface that can be used for quantum networking and quantum computing. Because the T-center technology operates natively in the O-band of telecom wavelengths, it has the potential to scale globally using existing telecom fibers.

Further, Microsoft said, the demonstration showcases the potential to operate a quantum computer in an industrial setting by using teleportation to execute logic gates between qubits in different locations. “Large-scale quantum algorithms running across multiple quantum computers require enormous amounts of distributed entanglement to work well,” Simmons said.

This achievement, according to a published scientific paper from the collaborators, pushes the state of quantum technology toward “Phase 3,” which Photonic defined as the era of quantum supercomputers and networked quantum computing. The phase will also unlock fault-tolerant quantum networking applications like global entanglement distribution protocols and blind quantum computing, the paper said.

In Phase 2, where the technology currently resides, Photonic said, single quantum modules can demonstrate quantum error correction protocols like surface code or quantum low-density parity-check, which, while useful, will not be able to handle many known algorithms desired by the commercial market.

The demonstration of distributed entanglement marks the completion of the first of three collaborative goals, Microsoft said. The next goal is to deliver a quantum repeater capable of capturing, entangling, and holding quantum information reliably for a short time.