The Canadian company D-Wave Systems has been selling its D-Wave quantum computers since 2011. NASA, Google or Lockheed Martin bought it for themselves but not everyone was able to believe in their operation. Now all speculations should be cut off, because an international team of physicists has confirmed that D-Wave really does work.
Canadian company D-Wave Systems has been selling its D-Wave quantum computers since 2011. It was purchased for themselves by NASA, Google and Lockheed Martin among others however not everyone was able to believe in their operation. Now all speculations should be cut off as an international team of physicists has confirmed that D-Wave really works.
Classic computers operate on bits – units of information with a state of 1 or 0, and everything takes place in transistors that are turned on and off inside the processor. A quantum computer, however, works differently – the bits are in a quantum state where they can store several values at once, and so their computing power grows exponentially – just 300 qubits would allow you to work with as many numbers as there are atoms in the universe.
The problems of D-Wave come from the fact that the company abandoned the standard logic gate model – because it is very difficult to keep the qubits (quantum bits) in their quantum state – spontaneous decoherence occurs and they behave like classical bits – they take the state 1 or 0. Quantum entangled bits (i.e. qubits) are encased in very complicated electronics and the so-called quantum annealing is used there, which significantly limits the possibilities of using such a computer.
D-Wave operation has been studied before. The simplest possible method was then used – a series of tasks were developed that D-Wave had to solve, and its results were compared with models for classical and quantum computers.
It was then possible to confirm that quantum annealing really does occur there, and not “ordinary” simulated annealing. Simulated annealing involves randomly sifting through a space of alternatives to select the best one – which the researchers illustrate with an analogy – it’s like walking across a terrain – its mountains and valleys – in search of the lowest point. In quantum annealing, however, you don’t have to walk on the terrain, but you can, as it were, move by “penetrating” the terrain – enabled by an effect called quantum tunneling (a particle can cross a potential barrier with a height greater than the particle’s energy), whereby individual qubits are connected to each other – aware, as it were, of what processes are taking place in the others.
In that study, D-Wave proved its worth, but more tangible proof was still needed, so researchers from Google, the University of Southern California in Los Angeles, Simon Fraser University and Tomsk Polytechnic University developed a different method – using one of the qubits as a probe to study the quantum state of the other qubits. And once again they were able to confirm that D-Wave really is a quantum computer – the qubits were entangled and coherent.
This means that the quantum computer based on the annealing algorithm actually works, and now there is the (no less complicated) issue of scaling it up and fine-tuning it. Due to its unique architecture, the D-Wave needs to be slightly rebuilt for each task, and it is not able to handle every problem (for example it cannot handle the Shor factorization algorithm) – so for now it looks more like a quantum version of an abacus than a computer (although for these selected problems the abacus is orders of magnitude faster than classical computers anyway).
Having in mind however, that 60 years ago first electronic computers also could be described in this way there is a hope that in a dozen years or so quantum computers will be perfected so much that it will be possible to use them every day and there will come to another revolution in technology.