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