How do you build the next-gen­er­a­tion In­ter­net?

Iran Daily - - Science & Technology -

prob­lems in the body; or to speed up how we de­sign bat­ter­ies, new ma­te­ri­als and Àex­i­ble elec­tron­ics.

Pool­ing com­put­ing power

Quan­tum com­put­ers might be more pow­er­ful than clas­si­cal com­put­ers, but some ap­pli­ca­tions will re­quire even more com­put­ing power than one quan­tum com­puter can pro­vide on its own.

If you can get quan­tum de­vices to talk to each other, then you could con­nect sev­eral quan­tum com­put­ers to­gether and pool their power to form one huge quan­tum com­puter.

How­ever, since there are four dif­fer­ent types of quan­tum com­put­ers be­ing built to­day, they won’t be all be able to talk to each other with­out some help.

Some sci­en­tists fa­vor a quan­tum In­ter­net based en­tirely on light par­ti­cles (pho­tons), while oth­ers be­lieve that it would be eas­ier to make quan­tum net­works where light in­ter­acts with mat­ter.

Joseph Fitzsi­mons, a prin­ci­pal in­ves­ti­ga­tor at the Na­tional Uni­ver­sity of Sin­ga­pore’s Cen­ter of Quan­tum Tech­nolo­gies, said, “Light is bet­ter for com­mu­ni­ca­tions, but mat­ter qubits are bet­ter for pro­cess­ing.

“You need both to make the net­work work to es­tab­lish er­ror cor­rec­tion of the sig­nal, but it can be dif¿cult to make them in­ter­act.”

It is very ex­pen­sive and dif¿cult to store all in­for­ma­tion in pho­tons, Fitzsi­mons said that is be­cause pho­tons can’t see each other and pass straight by, rather than bounc­ing off each other.

In­stead, he be­lieves it would be eas­ier to use light for com­mu­ni­ca­tions, while stor­ing in­for­ma­tion us­ing elec­trons or atoms (in mat­ter).

Quan­tum en­cryp­tion

Quan­tum en­cryp­tion will make com­mu­ni­ca­tions much more se­cure

One of the key ap­pli­ca­tions of the quan­tum In­ter­net will be quan­tum key dis­tri­bu­tion (QKD), whereby a se­cret key is gen­er­ated us­ing a pair of en­tan­gled pho­tons, and is then used to en­crypt in­for­ma­tion in a way that is im­pos­si­ble for a quan­tum com­puter to crack.

This tech­nol­ogy al­ready ex­ists, and was ¿rst demon­strated in space by a team of re­searchers from the Na­tional Uni­ver­sity of Sin­ga­pore and the Uni­ver­sity of Strath­clyde, the UK, in De­cem­ber 2015.

But it’s not just the en­cryp­tion that we will need to build in or­der to se­cure our in­for­ma­tion in the quan­tum fu­ture.

Sci­en­tists are also work­ing on ‘blind quan­tum com­puter pro­to­cols’, be­cause they al­low the user to hide any­thing they want on a com­puter.

Fitzsi­mons said, “You can write some­thing, send it to a re­mote com­puter and the per­son who owns the com­puter can’t tell any­thing about it at all ex­cept how long it took to run and how much mem­ory it used.

“This is im­por­tant be­cause there likely won’t be many quan­tum com­put­ers when they ¿rst ap­pear, so peo­ple will want to re­motely run pro­grams on them, the way we do to­day in the cloud.”

There are two dif­fer­ent ap­proaches to build­ing quan­tum net­works — a land-based net­work and a space-based net­work. Both meth­ods work well for send­ing reg­u­lar bits of data across the In­ter­net to­day, but if we want to send data as qubits in the fu­ture, it is much more com­pli­cated.

To send par­ti­cles of light (pho­tons), we can use ¿ber op­tic ca­bles in the ground.

How­ever, the light sig­nal de­te­ri­o­rates over long dis­tances (a phe­nom­e­non known as ‘de­co­her­ence’), be­cause ¿ber op­tics ca­bles some­times ab­sorb pho­tons.

It is pos­si­ble to get around this by build­ing ‘re­peater sta­tions’ ev­ery 50km.

These would es­sen­tially be minia­ture quan­tum lab­o­ra­to­ries that would try to re­pair the sig­nal be­fore send­ing it on to the next node in the net­work.

But this sys­tem would come with its own com­plex­i­ties.

How does quan­tum dis­tri­bu­tion work? key

To un­der­stand how QKD works, let’s go back to the video call made be­tween the Aus­trian and Chi­nese sci­en­tists.

The Mi­cius satel­lite used its light source to es­tab­lish op­ti­cal links with the ground sta­tions in Aus­tria and the ground sta­tions in China.

It was then able to gen­er­ate a quan­tum key.

The great thing about quan­tum en­cryp­tion is you can de­tect whether some­one has tried to in­ter­cept the mes­sage be­fore it got to you, and how many peo­ple tried to ac­cess it.

Mi­cius was able to tell that the en­cryp­tion was se­cure and no one was eaves­drop­ping on the video call.

It then gave the go ahead to en­crypt the data us­ing the se­cret key and trans­mit it over a pub­lic In­ter­net chan­nel.

Quan­tum en­cryp­tion will make com­mu­ni­ca­tions much more se­cure. bbc.com

bbc.com The video call be­tween Aus­trian and Chi­nese sci­en­tists on Septem­ber 29, 2017.

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