States and businesses : the race for quantum computers

Pre­sident Macron recent­ly announ­ced the French Natio­nal ‘Plan Quan­tique’, pro­mi­sing a sum of €1.8 bil­lion to quan­tum research over the next ten years. As a resear­cher in the field of quan­tum phy­sics, why is the French govern­ment paying so much atten­tion to the field now, specifically ? 

Lan­dry Bre­theau. It is hap­pe­ning now because it’s the right time – there are many who say we are ente­ring the second quan­tum revo­lu­tion. Bea­ring in mind that the first quan­tum revo­lu­tion hap­pe­ned in the 1920–30s, with the work of now hou­se­hold-named scien­tists like Ein­stein or Planck. 

Back then it was first a concep­tual revo­lu­tion when we came to unders­tand concepts like ‘wave-par­ticle dua­li­ty’, ‘black-body radia­tion’ and ‘light-mat­ter inter­ac­tion’, which until quan­tum phy­sics arri­ved scien­tists couldn’t explain. Their dis­co­ve­ries gave rise to game-chan­ging tech­no­lo­gies that moved engi­nee­ring into the digi­tal age, like lasers and tran­sis­tors. The lat­ter allow us to control elec­tro­nic signals, an impor­tant tech­no­lo­gy for com­pu­ter processors. 

There was, howe­ver, an aspect that was confu­sing to resear­chers – the concept of quan­tum entan­gle­ment. Without going into too much detail, it was unk­nown for a long time whe­ther the entan­gle­ment they pre­dic­ted was a natu­ral phe­no­me­non or due to a misun­ders­tan­ding of quan­tum phy­sics. We now know that it is natu­ral, thanks to expe­ri­ments that were per­for­med on indi­vi­dual quan­tum objects, in par­ti­cu­lar in the research of Prof. Alain Aspect, a pio­neer in the field. He has actual­ly been very ins­tru­men­tal in pro­mo­ting the second quan­tum revo­lu­tion and convin­cing the govern­ment that fun­ding research is a good investment.

What is the signi­fi­cance of such a proposal ? 

In short, the ‘Plan Quan­tique’ is on the table because there is a pro­mise of new tech­no­lo­gies. Now that the phe­no­me­non of entan­gle­ment has been well esta­bli­shed, it is pos­sible to ima­gine future appli­ca­tions using quan­tum tech­no­lo­gies for cal­cu­la­tion, com­mu­ni­ca­tions, sen­sing and simu­la­tion with poten­tial spi­noffs in ener­gy, health and secu­ri­ty. But the main sel­ling point, so to say, is the quan­tum com­pu­ter.

Many people will have heard of quan­tum com­pu­ters without kno­wing what they are, and it must be said that the word ‘com­pu­ter’ is slight­ly mis­lea­ding. It is unli­ke­ly that we will see a uni­ver­sal quan­tum com­pu­ter in the future that will replace the PC or smart­phone, for example. Rather, quan­tum com­pu­ters are actual­ly super-cal­cu­la­tors, capable of run­ning spe­ci­fic power­ful quan­tum algo­rithms much fas­ter than an ordi­na­ry processor.

The idea is to exploit quan­tum phe­no­me­na such as super­po­si­tion and entan­gle­ment to per­form fas­ter com­pu­ta­tion. A quan­tum com­pu­ter mani­pu­lates infor­ma­tion using a large num­ber of quan­tum bits, that can be pre­pa­red in mas­si­ve­ly entan­gled states. This allows one to encode mul­tiple com­pu­ta­tio­nal results in a single step, in a phe­no­me­non known as quan­tum paral­le­lism. This can lead to a quan­tum speed-up for spe­ci­fic algo­rithms, such as “prime fac­to­ri­sa­tion”, which is the basis for RSA encryp­tion. This encryp­tion method is com­mon­ly used for secure data trans­mis­sion in par­ti­cu­lar in ban­king ope­ra­tions. Even though cra­cking RSA secu­ri­ty is extre­me­ly dif­fi­cult with a stan­dard com­pu­ter, a quan­tum com­pu­ter could do it much fas­ter and thus decode encryp­ted communications.

That is why there is much inter­est in this tech­no­lo­gy, par­ti­cu­lar­ly in terms of mili­ta­ry defence. If some states have that capa­bi­li­ty, then it could become a mili­ta­ry issue. Hence why the US Depart­ment of Defense is hea­vi­ly fun­ding a research pro­gram into quan­tum computing. 

Big tech com­pa­nies like Google and Face­book are alrea­dy inves­ting in quan­tum com­pu­ters, as are the USA and Chi­na. Is there much hope that France will be able to keep up ? 

Since 2018 the USA announ­ced a $2bn invest­ment in research and Chi­na is said to have spent at least $10bn on their Natio­nal Labo­ra­to­ry for Quan­tum Infor­ma­tion Sciences. In Europe, fun­ding has been going on for some time now too. Ger­ma­ny star­ted their pro­gram three years ago and the EU has been fun­ding the Quan­tum Flag­ship pro­ject since 2018, offe­ring €1bn over the next ten years. So, yes, the ‘Plan Quan­tique’, which is based on the high-level research alrea­dy present in France, will help us to keep up –we weren’t the first but we are very well positioned.

The French pri­vate sec­tor will also be invol­ved too, though. Natio­nal and Euro­pean com­pa­nies like Total and Air­bus have pro­mi­sed to invest. And start-ups are pop­ping up across the coun­try ; Quan­de­la, Pas­qal and Alice & Bob, to name but three, are spi­noffs from French research labo­ra­to­ries. So far, nobo­dy has a ful­ly func­tio­ning quan­tum com­pu­ter with any mea­ning­ful pro­ces­sing power. Google is among the fur­thest along, with a pro­ces­sor that is limi­ted to 53 quan­tum bits. This is tru­ly an expe­ri­men­tal tour de force but it is still too small at the moment for any use­ful application. 

You might say, “oh well let’s just add more qubits to make the pro­ces­sor more power­ful.” But there comes the pro­blem. Quan­tum states are high­ly fra­gile – the more you have, the less stable it becomes. Hence, quan­tum com­pu­ters need to be high­ly confi­ned, i.e. iso­la­ted from their envi­ron­ment. This, howe­ver, in itself creates a para­dox because the more confi­ned it is, the har­der it is for us to actual­ly com­mu­ni­cate with the com­pu­ter to control what it does. 

What will this mean for French research on quan­tum physics ? 

It’s not tomor­row that we will have a quan­tum com­pu­ter. But fun­ding like this is a way of ope­ning up our chances and I think it’s a great thing that the money is being put for­ward. We might not even get a ful­ly ope­ra­ting quan­tum com­pu­ter in ten years, but it is cer­tain that we will dis­co­ver other exci­ting things along the way. And even when we’ll create one, it is unli­ke­ly to be an eve­ry­day item. Quan­tum com­pu­ters will more like­ly be stra­te­gic tools, enabling spe­ci­fic appli­ca­tions and used for basic research, R&D or govern­ment purposes. 

Moreo­ver, inno­va­tions will not only take place on the hard­ware level (i.e. the machines them­selves). There is also a need for new ideas in terms of soft­ware, too. Theo­re­ti­cal research, at the inter­face bet­ween phy­sics, com­pu­ter science and mathe­ma­tics, must the­re­fore dis­co­ver new algo­rithms for quan­tum acceleration.

Such fun­ding is very encou­ra­ging for young people ente­ring the labour mar­ket ! It can be help­ful in choo­sing their career and encou­rage more to become quan­tum resear­chers or engi­neers. That being said, it is worth poin­ting out that there are alrea­dy IBM quan­tum com­pu­ters acces­sible via the cloud. Even if their per­for­mance remains rather limi­ted, they allow stu­dents to fami­lia­rise them­selves with quan­tum com­pu­ting, and to car­ry out their first experiences !

Inter­view by James Bowers