FEATURE: NEXT GENERATION OPTICAL NETWORKS
MAKING A QUANTUM LEAP
INTO COMMERCIAL FIBRE NETWORKS
FEATURE: SUBMARINE NETWORKS
Quantum memories containing many atoms have been entangled via commercial fibre links
Progress is being made on entanglement methods that can work in mainstream telecom wavelengths, in conventional networks
ANDY EXTANCE A
www.fibre-systems.com @fibresystemsmag
fter more than a decade’s work, the prospect of full quantum networks exploiting entangled photons is drawing closer. Tat’s thanks to the
work of researchers like Hee Su Park from the Korea Research Institute of Standards and Science (KRISS). From 2005 to 2010 he built up a quantum
optics lab to develop measurement techniques for quantum information technologies. He wanted to find out to what extent optical fibres guiding multiple spatial modes can be used for quantum communications. Quantum networks encourage ‘collaboration by scientists in diverse fields, and surely inspire a lot of novel and interesting ideas,’ Park explained. And, findings from scientists like Park are
already suggesting ways in which quantum networks could be integrated with fibre networks. Experimental approaches previously used different wavelengths of light and different types of fibre to the predominantly single- mode, single core fibre infrastructure that today underlies the internet. But, new methods
increase the chances that quantum networks might integrate with existing systems. It may be at least 20 years until that becomes a reality – but findings are already being published that put the process in motion. For quantum networks, the key physical
phenomenon to harness is entanglement, where properties of at least two different particles are correlated. In quantum computers, entanglement enables calculations that are extremely difficult for classical computers, in applications such as code-breaking and simulating chemical systems.
Spin city Andrew Forbes from the University of the Witswatersrand in Johannesburg, South Africa, groups the ways quantum communication experiments entangle photons into two extremes. Te most common approach exploits correlation between the polarisation, or spin angular momentum, of two photons. In 2019 researchers at the Institute for Quantum Optics and Quantum Information (IQOQI) in
Issue 27 n Spring 2020 n FiBRE SYSTEMS 9
Quantop
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