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Students demo fibre on steroids

A team from Wits University in South Africa and HUST in China show that multi-dimensional quantum communications with twisted light is possible down fibre networks

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Picture: University of the Witwatersrand

A PhD student at Wits University, along with colleagues from Wits and Huazhang University of Science and Technology in Wuhan, China, have found a way to transfer data securely across optical fibre networks.

The team, led by Wits Professor Andrew Forbes, has demonstrated that multiple quantum patterns of twisted light can be transmitted across a conventional fibre link that, paradoxically, supports only one pattern. The research, published in Science Advances, opens up the way to securely transport data across fibre networks, using multiple dimensions of light. Combined with the qualities of entangled quantum light, this data transfer can also now be done in a highly secure manner, which was previously not possible.

“Our team showed that multiple patterns of light are accessible through conventional optical fibre that can only support a single pattern,” says Wits PhD student, Isaac Nape, one of the leading PhD students on the team. “We achieved this ‘quantum trick’ by engineering the entanglement of two photons. We sent the polarised photon down the fibre line and accessed many other patterns with the other photon.”

Entanglement is when a pair or group of particles (such as photons) interact in such a way that the quantum state of each of the particles cannot be described independently of the state of the others, even when the particles are separated by a large distance. In other words, qualities such as the handedness (like left or right) of the one entangled particle will directly affect its entangled counterpart.

In this case, the researchers manipulated the qualities of the photon on the inside of the fibre line, by changing the qualities of its entangled counterpart in free space.

“In essence, the research introduces the concept of communicating across legacy fibre networks with multi-dimensional entangled states, bringing together the benefits of existing quantum communication with polarised photons with that of high-dimension communication using patterns of light,” says Forbes.

In the last few decades, quantum entanglement has been extensively explored for a variety of quantum information protocols, notably making communication more secure through Quantum Key Distribution (QKD).

Using so-called “qubits” (2D quantum states) the information capacity is limited but it is easy to get such states across fibre links using polarisation as a degree of freedom for the encoding.

The spatial pattern of light is another degree of freedom that has the benefit of high-dimensional encoding. However, while you can use many patterns of light in communications, this requires custom fibre optical cable, so it is unsuitable to already existing networks. 

“Our team found a new way to balance these two extremes, by combining polarisation qubits with high-dimensional spatial modes to create multi-dimensional hybrid quantum states,” says Nape.

“The trick was to twist the one photon in polarisation and twist the other in pattern, forming ‘spirally light’ that is entangled in two degrees of freedom,” says Forbes. “Since the polarisation entangled photon has only one pattern, it could be sent down the long-distance single-mode fibre, while the twisted light photon could be measured without the fibre, accessing multi-dimensional twisted patterns in the free-space. These twists carry orbital angular momentum (or spin), a promising candidate for encoding information.”

The team demonstrated transfer of multi-dimensional entanglement states over 250 m of single-mode fibre, showing that an infinite number of two-dimensional subspaces could be realised. Each subspace could be used for sending information, or multiplexing information to multiple receivers.

“A consequence of this new approach is that multiple patterns of light can be used in the fibre, but two at a time. It is a compromise because you can still get to “infinity” but by adding 2+2+2 … rather than in just one step,” says Forbes. Importantly, high-dimensional states are unsuitable for transmission over conventional fibre networks, whereas this new approach allows legacy networks to be used.

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TikTok takes on COVID-19

The fastest growing social media platform in the world has also become an epicenter of public education about the coronavirus, attracting more than 30-billion views, writes ARTHUR GOLDSTUCK

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The young have been getting a bad rap for wanting to party on while COVID-19 sends the world into lockdown. But a different movie is playing itself out on the social platform that is growing fastest among teenagers: TikTok.

Awareness campaigns by TikTok itself, collaboration with the International Red Cross, and spontaneous videos made by TikTok creators have combined into a barrage of information, education, awareness and social consciousness around the coronavirus.

Both globally and in South Africa, TikTok’s COVID-19 campaigns have gone viral.

The local #HayiCorona challenge, designed to remind people not to touch their face and wash hands regularly, has passed 1.5-million views. The TikTok collaboration with the International Red Cross, the #WashingHands challenge, has passed 12.6-million views.

One of the best-known participants in these challenges is the past year’s icon of South African talent, the Ndlovu Youth Choir, took up the global challenge with a 20-second hand-washing video. It put together a performance that brings tremendous energy to what can be a clichéd message, and ends with a punt for the Department of Health’s WhatsApp information service. The video can be viewed below.

@ndlovuyouthchoir

Our community has limited access to running water. Follow these instructions on how to safely wash your hands using a bucket. ##coronavirus##washinghands

♬ original sound – ndlovuyouthchoir

“On a global scale, TikTok also partnered with the World Health Organization (WHO) to ensure that, while creators are still having fun and expressing themselves on the platform, they stay informed with COVID-19 information coming from a reliable source,” a TikTok spokesperson told us. “Through the partnership, the WHO has created an informational page on TikTok that offers information to curb the spread of the coronavirus as well as dispelling myths.”

The page can be viewed at https://vm.tiktok.com/GHTEGf

TikTok has hosted a number of livestreams with WHO experts, attracting users from more than 70 countries, tuning in for live question and answer sessions. It has also introduced labels on coronavirus-related videos, to point users to trusted information. Resources are also offered directly in the app and in a dedicated COVID-19 section of TikTok’s Safety Center, at https://www.tiktok.com/safety/resources/covid-19.

If users simply want to explore videos on the topic, they can search via the #coronavirus hashtag, or click on https://vm.tiktok.com/swKbn4. The hashtag has had an astonishing 33.8-billion views, indicating the scale of activity and interest around the topic on the platform.

Read more on the next page about how South Africans have embraced the campaign.

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On World Backup Day: backup, backup, backup

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It was World Backup Day yesterday, 31 March, at a time when business continuity is threatened as never before. That makes calls for protecting email and defending against ransomware all the more urgent.

The global coronavirus pandemic has brought into stark relief many organisations’ lack of business continuity plans and policies. With more than two billion people around the globe in forced lockdown in wide-ranging government efforts to stem the tide of infections, an unprecedented number of employees are working remotely.

This interruption to the normal way of work is precisely what an effective and resilient business continuity strategy should plan for, says Heino Gevers, cybersecurity specialist at Mimecast

“Companies need uninterrupted access to critical business applications during times of disruption, including safe and secure web and email access for workers that are now operating outside the normal perimeters of the organisation,” he says. “In addition, comprehensive backup and archiving solutions should be ready to restore access to critical business applications should there be any unplanned downtime to ensure continuity until the crisis passes.”

According to Gevers, the current global crisis is likely to push business continuity up the list of priorities for many organisations that have been disrupted by the effects of the coronavirus.

“Organisations are facing new challenges to their productivity; for example in terms of technical support. If a remote user is infected with malware or ransomware, how does the IT team restore that device or do any remediation without being able to physically access it?”

Gevers advises that organisations implement tools that enhances the data protection capabilities of commonly-used tools such as Office365 and can leverage archived data to provide quick recovery of email data in the event of accidental loss, malicious attacks or technical failure. 

“As adoption of cloud-based business applications grow in the wake of forced lockdowns around the globe, companies need to ensure they have the tools to recover in any situation,” he says. “This includes a data management strategy that combines archiving, backup and data protection capabilities to allow for quick restoration of critical systems and applications in the event of disruption.”

Jasmit Sagoo, head of technology at Veritas for the United Kingdom and Ireland, warns that this is a golden age for cybercriminals looking for ransomware opportunities.

“As the global cost of ransomware continues to grow, this World Backup Day, Veritas is saying: ‘don’t pay up, back up!’,” he says. “Ransomware is said to generate an estimated annual revenue of $1 billion a year, and companies who are not consistent in backing up their data are allowing criminals to line their pockets.

“Ransomware attacks exist only because some businesses can’t survive unless the hackers give them back their data.  So, the key to survival is removing that reliance and being able to regain access to data, without engaging with the cybercriminals.  The best way to do that is with a sound backup strategy.

“Sagoo advises organisations to create isolated, offline backup copies of their data to keep it out of reach of any attackers.  They then need to proactively monitor and restrict backup credentials, while running backups frequently to shrink the risk of potential data loss. Businesses should also test and retest their ransomware defences regularly.

“Ransomware strikes without warning and it doesn’t discriminate between its targets – it can happen to any organisation, large or small. Despite their best efforts, most companies will fall to at least one attack. What distinguishes one victim from another is the ability to bounce back, which ultimately depends on its backup strategy.

“When ransomware hits, organisations that aren’t prepared often feel helpless to do anything other than to submit to their attacker’s demands.   That’s why we’re urging all businesses to use World Backup Day as a catalyst to get ahead of the situation and get their data protected.”

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