According to Google the D-Wave 2X quantum computer offers extraordinary performances
Google published a series of results obtained with the D-Wave 2X quantum computer, a system purchased to use it together with NASA. The fuss came from the fact that tests showed performance a hundred million times greater than those of a traditional processor. The problem is that these results are achieved only for specific operations ending up adding new controversy around these systems.
In May 2013 Google and NASA announced the opening of the Quantum Artificial Intelligence Laboratory (QuAIL) with the installation of a D-Wave Two quantum computer. In September 2015 the installation of a more advanced model was announced, the D-Wave 2X, the one used for the test published by Google.
The processors that power the computers designed by D-Wave Systems use the method called quantum annealing. For the tests conducted by Google, the comparison was made with a traditional system which used a method called simulated annealing, which allows to approximate with a probabilistic technique certain operations of a quantum computer. The D-Wave 2X was over a hundred million times faster than a traditional single core system that used the method of simulated annealing.
The tests also included a comparison of the quantum system D-Wave 2X with a traditional system that used an algorithm of the quantum Monte Carlo family, exploited to simulate quantum computers. In this case, the performance differences varied but can still be a hundred million times greater than those of the traditional system that uses a quantum Monte Carlo algorithm.
The problem is that in simple words these tests only prove that a quantum system can provide a performance extremely superior to those of a simulation of that type of system. In essence, these tests bring out the best possible conditions for the D-Wave 2X quantum system.
The conditions are almost opposite to those of a test that last year gave disappointing results on a D-Wave Two system. It must be pointed out that the quantum computer used now has a higher level than the previous one, with a 1,000+ qubit quantum processor.
The Google team that participates in the use of the D-Wave systems will seek to optimize their use. However, doubts remain about the practical uses of this type of quantum computers, which add to the controversy that always exist around the D-Wave systems. At least for now, they appear to be really valuable only for certain types of uses.
