Beam Us Up One Day, Scotty?

The Economic Times - - Breaking Ideas - Prakash Chan­dra

When news broke last month of Chi­nese re­searchers suc­cess­fully tele­port­ing a pho­ton — a par­ti­cle of light — from an in­stru­ment on the Ti­betan plateau to an or­bit­ing satel­lite 1,400 km away in space, it sent a fris­son of ex­cite­ment through the sci­en­tific com­mu­nity. But it wasn’t quite ‘Beam me up, Scotty’ time yet.

When physi­cists talk about teleportation, they mean the cre­ation of a sin­gle par­ti­cle that can be in two or more states at the same time, and trans­fer­ring char­ac­ter­is­tics that de­fine the par­ti­cle’s na­ture and be­haviour to its twin with­out us­ing any phys­i­cal link. The par­ti­cles share their ‘quan­tum states’ — such as en­ergy, mo­tion and mag­netic field — re­gard­less of the dis­tance sep­a­rat­ing them.

Sci­en­tists have known for decades that teleportation is pos­si­ble us­ing a process called ‘quan­tum en­tan­gle­ment’ — at least for sub­atomic par­ti­cles. This in­volves what Al­bert Ein­stein fa­mously de­scribed as “spooky ac­tion at a dis­tance” be­tween two linked par­ti­cles that are cre­ated at the same time and place so that es­sen­tially they have the same ex­is­tence. The en­tan­gle­ment so en­twines the fate of each in­ex­tri­ca­bly that if one changes its state, the other takes on its old prop­er­ties and be­comes a replica of the first’s orig­i­nal state.

This ‘en­tan­gled’ state con­tin­ues even if you sep­a­rate the par­ti­cles: if one par­ti­cle changes, its dop­pel­gänger in the other lo­ca­tion also changes. This goes against the known laws of physics where we are used to ev­ery­day ob­jects be­hav­ing in fa­mil­iar ways.

Till now, this abil­ity to trans­fer key prop­er­ties from a quan­tum par­ti­cle to an­other has been con­fined to ex­per­i­ments at lim­ited dis­tances. So how did the Chi­nese tele­port a pho­ton many times this dis­tance into space? Well, pho­tons can travel eas­ily through the vacuum of space, pro­vided they are able to ne­go­ti­ate Earth’s fickle at­mo­spheric con­di­tions on their way out first.

The Chi­nese ap­par­ently cre­ated thou­sands of quan­tum-en­tan­gled pairs of pho­tons per sec­ond and al­lowed one from each pair to ride a shaft of light that was beamed to­wards an or­bit­ing satel­lite. A su­per­sen­si­tive re­ceiver on board the satel­lite de­tected the quan­tum states of the sin­gle pho­tons coming its way so that the en­tan­gled pho­tons could be trans­mit­ted to ground sta­tions.

The phan­tom char­ac­ter of quan­tum par­ti­cles that lets them be tele­ported — the si­mul­ta­ne­ous ex­is­tence of two of a kind — can be used for de­vel­op­ing quan­tum com­put­ers. Here, in­for­ma­tion is pro­cessed in the form of qubits used in com­put­ers to­day. With quan­tum com­put­ing, you can have cen­tral pro­cess­ing el­e­ments smaller than a sugar crys­tal that can carry out unimag­in­ably com­plex com­pu­ta­tions and they are faster, too. And this also means prac­ti­cally ‘un-hack­able’ cryp­tog­ra­phy as data en­cryp­tion us­ing qubits is prac­ti­cally un­break­able.

So, will hu­man teleportation be a re­al­ity some­day? Tele­port­ing pho­tons or atoms is one thing, and tele­port­ing peo­ple quite an­other. To va­por­ise a hu­man made up of zil­lions (one with 27 ze­ros) of atoms and ac­cu­rately re­assem­ble them else­where seems well-nigh im­pos­si­ble. Even the data pro­cess­ing required to tele­port, say, a teacup, with­out the tea, would take many times the age of the uni­verse.

True, in prin­ci­ple, the laws of physics al­low you to recre­ate any­thing any­where, pro­vided you sat­isfy two key con­di­tions: that you have the req­ui­site pro­cess­ing power, and are willing to de­stroy the orig­i­nal (teleportation de­stroys the ob­ject be­fore re­con­struct­ing it). Quan­tum trav­ellers would, there­fore, be vir­tu­ally killed if they tried to travel in this way, as it’s only their ‘copy’ that emerges at the other end.

Per­haps, in some far fu­ture, hu­mans may build a de­vice sim­i­lar to the ‘beam trans­porter’ in Star Trek. In­side the trans­porter, com­put­ers cod­ify your atomic struc­ture and trans­mit it on laser beams across the uni­verse. At the des­ti­na­tion, this ‘quan­tum com­mu­ni­ca­tion’ is re­ceived by com­put­ers that use vats of chem­i­cals to re­con­struct you in your orig­i­nal im­age. And lo! You are ready to check your ar­rival and beam-out data from which­ever uni­verse you may be in.

Scale up quan­tum en­tan­gle­ment

Newspapers in English

Newspapers from India

© PressReader. All rights reserved.