Study: D-Wave is world's first quantum computer, not simulation

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Jun 30, 2014

Quantum computer manufacturer D-Wave has been under a lot of scrutiny. Although D-Wave calls their machine a quantum computer, many skeptics question whether this computer is actually using quantum physics in its processesĀ or whether it's just been simulating those processes using classical mechanics. A team of researchers has put the D-Wave to the test. The result? The researchers concluded that the D-Wave is in fact an actual quantum computer. Phew.

Both Google and NASA believe that quantum computing is a valuable tool for analyzing big data, as well as the key to creating true artificial intelligence. But quantum computers are much more complicated than standard computers. Take your PC or laptop, for example, which does calculations with bits that either have a value of zero or one. Instead, quantum computers work with qubits that can have a value of zero, one, or both. They calculate probability by working out many calculations at one time. Because of this, quantum computers are a lot faster than your standard computer for a very specific subset of problems that can be exceptionally difficult for standard computers to solve.

The real magic of quantum computing happens with entanglement. This means that groups of information interact with each other in a way that creates a quantum state. In a quantum computer, this is when two qubits stop being separate entities and become linked with each other (a state called superposition). If you have two qubits and the state of one qubit changes, the other must also change, becoming complementary to the first. If you measure the first qubit, you can figure out what the second qubit is. This lets the quantum computer explore all possible outcomes of a calculation and figure out which one is the most probable. It runs the scenarios several times and outputs the most probable solution. What makes this technique so special is that a quantum computer does all of this at once, instead of sequentially.

Skeptics have been debating whether the D-Wave is, in fact, not really a quantum computer, but just a simulation of one. They did not believe that entanglement occurs inside the machine or that a quantum state is ever reached. However, researchers recently studied one of the qubits, using it for measurements of other qubits around it. These qubits showed signs of behavior that could only happen after entanglement.

This doesn't mean that D-Wave is a perfect example of quantum computing. In fact, the Google D-Wave machine failed to pass its first benchmark test. Also, there's not enough entanglement inside the machine happening to make it as fast as we want it: D-Wave's computer has 512 qubits, but only about 100 of those are actually getting used. Perhaps in time, a larger machine with more efficiently-operating qubits might be the quantum computer we're looking for.

Via Ars Technica