New photonic chip promises more robust quantum computers

Scientists have developed a topological photonic chip to process quantum information, promising a more robust option for evolutionary quantum computers.

The research team, led by Dr. Alberto Peruzzo of the RMIT University, demonstrated for the first time that quantum information can be encoded, processed and remotely transferred with the topological circuits of the chip. The research is published in Scientists progress.

This breakthrough could lead to the development of new materials, new generation computers, and a deep understanding of basic science.

In collaboration with scientists from the Politecnico di Milano and ETH Zurich, researchers used topological photonics – a rapidly growing field aimed at studying the physics of the topological phases of matter in a new optical context – to manufacture a chip with a beam splitter. a photonic quantum gate of high precision.

"We expect that the new chip design will pave the way for the study of quantum effects in topology materials and a new field of topologically robust quantum processing in integrated photonics technology," says Peruzzo, senior research scientist at the Center for Disease Control. ARC Excellence Communication Technology (CQC2T) and Director, Quantum Photonics Laboratory, RMIT.

"Topological photonics has the advantage of not requiring strong magnetic fields and exhibits intrinsically consistent operation at room temperature and easy handling," Peruzzo explains.

"These are essential requirements for scaling up quantum computers."

Replicating the well-known Hong-Ou-Mandel (HOM) experiment – which takes two photons, the ultimate constituents of light and interferes with them according to the laws of quantum mechanics – the team was able to use the photonic chip for the first time times, topological states may experience high fidelity quantum interference.

HOM interference is at the heart of optical quantum computation which is very sensitive to errors. Topologically protected states could add robustness to quantum communication, reducing noise and widespread defects in quantum technology. This is particularly interesting for the processing of optical quantum information.

"Previous research has focused on topological photonics using" conventional "laser light, which behaves like a classical wave.We use here single photons that behave according to quantum mechanics," said lead author Jean -Luc Tambasco. student at RMIT.

The demonstration of a high fidelity quantum interference is a precursor to the transmission of accurate data with the aid of single photons for quantum communications – an essential component of a global quantum network.

"This work cuts across the two burgeoning areas of quantum technology and topological insulators and can lead to the development of new materials, new generation computers, and basic science," Peruzzo said.

The research is part of the CQC2T quantum photonics program. The Center of Excellence develops parallel approaches using optical and silicon processors in the race for the development of the first quantum computing system.

Australian researchers at CQC2T have established global leadership in quantum information. Having developed unique technologies to manipulate matter and light at individual atoms and photons, the team demonstrated the highest fidelity, the longest coherence time of solid state qubits; the longest lasting quantum memory in the solid state; and the ability to execute small-scale algorithms on photonic qubits.

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More information:
"Quantum interference of topological states of light" Scientists progress (2018). avances.sciencemag.org/content/4/9/eaat3187