An international team of scientists has set a new record for the complexity possible on a quantum computing chip, bringing us one step closer to the ultra-secure telecommunications of the future.
A key component of quantum science and technology is the notion of entangled particles — typically either electrons or particles of light called photons. These particles remain connected even if separated over large distances, so that actions performed by one affect the behaviour of the other.
The research team have done something extraordinary — creating entangled photon states with unprecedented complexity and over many parallel channels simultaneously on an integrated chip.
Importantly, the chip was also created with processes compatible with the current computer chip industry, opening up the possibility of incorporating quantum devices directly into laptops and cell phones.
The researchers were led by Professor David Moss, the newly appointed Director of the Centre for Micro-Photonics at Swinburne University of Technology, and Professor Roberto Morandotti from the Institut National de la Recherche Scientifique (INRS-EMT) in Montreal, Canada.
The researchers used 'optical frequency combs' which, unlike the combs we use to detangle hair, actually help to 'tangle' photons on a computer chip.
Their achievement has set a new record in both the number and complexity of entangled photons that can be generated on a chip to help crack the code to ultra-secure telecommunications of the future, according to the researchers.
It also has direct applications for quantum information processing, imaging, and microscopy.
"This represents an unprecedented level of sophistication in generating entangled photons on a chip," Professor Moss says. "Not only can we generate entangled photon pairs over hundreds of channels simultaneously, but for the first time we've succeeded in generating four-photon entangled states on a chip."
Professor Morandotti says the breakthrough is the culmination of 10 years of collaborative research on complementary metal–oxide–semiconductor (CMOS) compatible chips for both classical and quantum nonlinear optics.
"By achieving this on a chip that was fabricated with processes compatible with the computer chip industry we have opened the door to the possibility of bringing powerful optical quantum computers for everyday use closer than ever before," Professor Morandotti says.
The groundwork for the research was completed while Professor Moss was at RMIT. The collaboration includes the City University of Hong Kong, University of Sussex and Herriot Watt University in the UK, Yale University, and the Xi’an Institute in China.