The CEO of a quantum computing company walked onto a stage at MIT and stood in front of an audience of professors, engineers and computer scientists.

Vern Brownell, CEO of D-Wave Systems Inc., looked out at the crowd and said, "I cannot explain how quantum computing works."

Was he heckled? Did attendees get up and leave? No.

No one in the audience stirred. There was no murmuring. Nobody laughed. No sidelong glances. Nothing.

Quantum computing is just that confusing. Some of the world's best physicists don't understand how it works.

Nobel Laureate physicist Richard Feynman is widely quoted as saying, "If you think you understand quantum mechanics, you don't understand quantum mechanics."

Despite how complex the idea of a quantum computer is and the fact that some physicists say we're as much as 50 years away from seeing one, D-Wave, a quantum computing company based in Burnaby, British Columbia, said it is building them.

NASA, Google and Lockheed Martin are testing them.

"If you want to buy a quantum computer, I can sell you one today," Brownell said at an MIT Tech Conference in February that focused on disruptive technologies.

Those kinds of statements have created a buzz in both the world of physics and the world of computing because many believe quantum computing holds a lot of promise. It's like the Holy Grail of supercomputing.

Think of a computer that could surpass the top classic supercomputers in some calculations, especially problems where you have to search through a lot of data, finding answers to questions so complex that machines like IBM's Blue Gene and Cray's systems might need hundreds of years to solve, or might never solve them.

D-Wave CEO Vern Brownell

Quantum computers might help researchers seeking cures for cancer, advance cryptography or find distant planets. They also could be used to simulate political and military situations, such as the unrest in Ukraine, enabling researchers or a government to test different options and see how they would affect the outcome.

Quantum computers rewrite the rules of how computing works.

Classic computers use bits -- ones and zeroes -- for processing instructions, and they work based on a series of instructions. Ask the computer a question, and it will move through the calculation in a linear, orderly way.

A quantum computer combines computing with quantum mechanics, one of the most mysterious and complex branches of physics. The field was created to explain physical phenomena, like the odd actions of subatomic particles, that classical physics fails to do.

One of the rules of quantum mechanics is that a quantum system can be in more than one state at once. But that concept goes against what's known of the world. Something can be green or red but it cannot be green and red at the same time.

That's not the case with quantum mechanics.

Each bit in a quantum machine -- known as qubits -- can be both a one and zero. It's about possibilities. When a qubit is constructed, it's built so you don't know if it's a one or a zero. It has the possibility of being both.