Introducing the largest quantum photonic processor to date

Quantum computers promise to propel computing far beyond what today’s computers are capable of, but this potential has yet to be realised. In their search for a way to demonstrate quantum supremacy, researchers working in the EU-funded PHOQUSING project are developing a hybrid computational system based on cutting-edge integrated photonics that combines classical and quantum processes.

The project’s goal is to develop a quantum sampling machine that will put Europe at the forefront of photonic quantum computing. With this goal in mind, PHOQUSING project partner QuiX Quantum in the Netherlands has created the largest quantum photonic processor compatible with quantum dots (nanometre-sized semiconductor crystals that emit light of various colours when illuminated by ultraviolet light). The processor is the central component of the quantum sampling machine, a near-term quantum computing device able to show a quantum advantage.

“Quantum sampling machines based on light are believed to be very promising for showing a quantum advantage,” reports a news item posted on the QuiX Quantum website. “The problem of drawing samples from a probability distribution, mathematically too complex for a classical computer, can be solved easily by letting light propagating [sic] through such quantum sampling machines. At the very core of quantum sampling machines there are large-scale linear optical interferometers, i.e. photonic processors.”The processor the research team developed is a “record-size” 20-mode silicon nitride photonic chip that is optimised for use at the near-infrared wavelength range, operating at a wavelength of 925 nanometres. According to a webinar video presenting the processor, the 20 input modes with 190 unit cells and 380 tuneable elements likely make this processor the most complex photonic chip available today. Besides the large number of modes, key features of the quantum photonic processor include low optical losses (of 2.9 decibels per mode) and high fidelity (99.5 % for permutation matrices and 97.4 % for Haar-random matrices). The turnkey processor also enables high-visibility quantum interference (98 %).

Prof. Fabio Sciarrino of PHOQUSING (PHOTONICS QUANTUM SAMPLING MACHINE) project coordinator Sapienza Università di Roma, Italy, observes in the QuiX Quantum news item: “The established high-performance photonic technology provided by QuiX Quantum is crucial for the success of the project as it addresses the need of science-to-technology transition needed for developing useful quantum computation.” The project brings together seven partners from France, Italy, the Netherlands and Portugal: five academic and research organisations and two industrial players, all European leaders in the field of quantum information processing and integrated photonics.

For more information, please see:

PHOQUSING project website