Just simulating the abilities of a 40-qubit quantum computer would use all the resources of any of the most advanced supercomputers in the world.

FORBES: Atoms Offer Giant Leap In Computing Power

Two weeks ago a team led by Isaac Chuang at IBM (nyse: IBM - news - people) disclosed that it had built a 5-qubit quantum computer and used it to solve a relatively simple mathematical problem.

FORBES: Atoms Offer Giant Leap In Computing Power

One advantage of this method of making a quantum computer is that the atomic qubit stores can be manipulated relatively easily.

ECONOMIST: Quantum computers

The D-Wave computer operates as an adiabatic quantum computer, and consists of a superconducting 128-qubit chip in a cryogenics system within a 10 square meter room.

FORBES: Lockheed Martin Installs Quantum Computer