Health, tech, space : quantum technology is already benefiting many sectors

This article is part of our spe­cial issue « Quan­tum : the second revo­lu­tion unfolds ». Read it here

Quan­tum phy­sics has now lar­ge­ly become part of our eve­ry­day lives. The “first quan­tum revo­lu­tion” led to a host of devices and tech­niques that we use almost eve­ry day. Lasers, elec­tro­nics, LED ligh­ting, pho­to­vol­taic panels, nuclear medi­cine – none of these eve­ry­day tech­no­lo­gies could be used without a detai­led know­ledge of the pro­cesses that take place on an ato­mic level, thanks to an unders­tan­ding of the beha­viour of ele­men­ta­ry par­ticles and the inter­ac­tions bet­ween mat­ter and light.

But quan­tum mecha­nics has not fini­shed chan­ging our world. The very latest dis­co­ve­ries from research labo­ra­to­ries fore­sha­dow a second quan­tum revo­lu­tion, in which mas­te­ry of the pro­cesses at work in the infi­ni­te­si­mal may once again pro­found­ly change the way we live, com­mu­ni­cate, and unders­tand the world. Let’s take a look at the next appli­ca­tions of quan­tum phy­sics in the indus­trial world.

The ever-finer control of elec­tron flows in ever-smal­ler devices has enabled elec­tro­nics to reach unpre­ce­den­ted levels of minia­tu­ri­sa­tion. In 2021, IBM announ­ced the deve­lop­ment of a chip made of 2 nano­metre tran­sis­tors, with a den­si­ty of 333 mil­lion tran­sis­tors per mm².

But in addi­tion to its elec­tri­cal charge, the elec­tron has ano­ther pro­per­ty cal­led “spin”. This quan­tum quan­ti­ty has no clas­si­cal equi­va­lent but can be com­pa­red to a “magne­tic moment”, as if the elec­tron were a tiny magnet rota­ting on itself. The prin­ciple of spin­tro­nics is the­re­fore to mani­pu­late the spin of elec­trons rather than their elec­tri­cal charge in order to create new appli­ca­tions, but also to dra­ma­ti­cal­ly reduce the power consump­tion of components.

Spin­tro­nics is alrea­dy being used in a num­ber of elec­tro­nic com­po­nents, inclu­ding com­pu­ter memo­ry (for which its dis­co­ve­rers won the Nobel Prize in Phy­sics in 2007) and cer­tain magne­tic sen­sors for cars and robotics.

Spin­tro­nics is alrea­dy used in a num­ber of elec­tro­nic com­po­nents, such as com­pu­ter memories.

But, as men­tio­ned above, the minia­tu­ri­sa­tion of elec­tro­nic devices is so advan­ced that their basic ele­ments will soon be the size of just a few atoms. A size that will make their beha­viour almost exclu­si­ve­ly quan­tum. To read and write on such small memo­ries, a team from the Ins­ti­tut Rayon­ne­ment-Matière de Saclay (IRa­MiS) has stu­died the beha­viour of a mole­cule (cal­led FeTTP) that nor­mal­ly plays a role in the trans­port of oxy­gen by hae­mo­glo­bin¹.

This mole­cule depo­si­ted on gra­phene (a layer of car­bon atoms one atom thick) can change spin easi­ly and at will. This consti­tutes a new read/write mecha­nism for a single mole­cu­lar spin, which is even smal­ler and more ener­gy-effi­cient than exis­ting devices.

Meanw­hile, the Nanos­ciences and Nano­tech­no­lo­gies Centre at the Uni­ver­si­ty of Paris-Saclay is trying to make arti­fi­cial intel­li­gence sys­tems more flexible². In conven­tio­nal com­pu­ter sys­tems, the basic infor­ma­tion is coded in the form of 0 or 1. New spin­tro­nic sys­tems make it pos­sible to intro­duce nuances into the bina­ry code, such as 0+ or 1- states, and to inte­grate this ‘fuz­zy’ logic into arti­fi­cial neu­ral net­works, which would ope­rate more like the orga­nic bio­lo­gi­cal neu­rons in our brains.

A large num­ber of sen­sors are built around dif­ferent quan­tum phe­no­me­na that give them the abi­li­ty to mea­sure minute signals with excellent reso­lu­tion, ope­ning up new fields of application.

In a micro­scope, the reso­lu­tion limit is deter­mi­ned by the pro­per­ties of the light used. Gene­ral­ly spea­king, it is not pos­sible to ‘see’ an object smal­ler than one wave­length of this light. In the visible range, this wave­length is around 500 nanometres.

In quan­tum phy­sics, there is a prin­ciple cal­led “wave-par­ticle dua­li­ty”, accor­ding to which quan­tum objects (par­ticles, atoms, etc.) exhi­bit the beha­viour of both par­ticles and waves. We can the­re­fore asso­ciate them with a wave­length, like light, and ima­gine a “mat­ter wave micro­scope”. The advan­tage is that the wave­length asso­cia­ted with atoms is 1 mil­lion times shor­ter than that of light. We the­re­fore have a mea­su­re­ment capa­bi­li­ty that is 1 mil­lion times bet­ter than that avai­lable with light.

With quan­tum phy­sics, we have a mea­su­re­ment capa­bi­li­ty that is 1 mil­lion times bet­ter than that avai­lable with light.

Such devices do exist. They are known, for example, as « iner­tial sen­sors using ato­mic inter­fe­ro­me­try ». The fields of appli­ca­tion are very broad, ran­ging from geos­ciences (detec­tion of oil slicks by mea­su­ring varia­tions in the local gra­vi­ty field) to life sciences (mea­su­re­ment of the elec­tric or magne­tic field emit­ted by a single cell) to iner­tial navi­ga­tion (on Earth or in space).

In 2022, an article in Nature out­li­ned the pos­si­bi­li­ty of a gra­vi­ty sen­sor of this type using the quan­tum beha­viour of free-fal­ling atoms to mea­sure micro­sco­pic varia­tions in the Ear­th’s gra­vi­ty more accu­ra­te­ly than ever before, in order to probe the struc­tures beneath the Ear­th’s surface.

The phar­ma­ceu­ti­cal indus­try has also long since embra­ced quan­tum mechanics.

Medi­cines are mole­cules that bind to other living struc­tures to pro­vide health bene­fits for the patient. The way in which these mole­cules inter­act with each other is stu­died by a spe­ci­fic scien­ti­fic field cal­led “quan­tum chemistry”.

Before a the­ra­peu­tic mole­cule is autho­ri­sed for the mar­ket, it must under­go a series of tests and cli­ni­cal trials that rare­ly take less than a decade. In order to tar­get mole­cules of inter­est very qui­ck­ly, there is a stage cal­led « vir­tual high-through­put scree­ning », where extre­me­ly com­plex algo­rithms test in paral­lel the abi­li­ty of thou­sands of mole­cules to demons­trate the desi­red bio­che­mi­cal effect on the target.

This unders­tan­ding of how an indi­vi­dual mole­cule che­mi­cal­ly binds to other nano­me­tric struc­tures requires the deve­lop­ment of digi­tal simu­la­tion tools incor­po­ra­ting all the prin­ciples of quan­tum mecha­nics and che­mis­try, with the aim of deli­ve­ring their results as qui­ck­ly as pos­sible, des­pite the colos­sal com­plexi­ty of the cal­cu­la­tions involved.

In France, a start-up cal­led Qbit phar­ma­ceu­ti­cals is deve­lo­ping new cal­cu­la­tion methods com­bi­ning neu­ral net­works, super­com­pu­ters and quan­tum com­pu­ters to tar­get the medi­cines of tomor­row ever more qui­ck­ly and effec­ti­ve­ly⁴.