Quantum Computing: Light Pulse Invention Making Computers More Powerful

Quantum computers have gotten more efficient with the invention of a new computing method that uses pulses of light to do more calculations at once.

The Japan Times reported that the method sends light pulses through the loop of a circuit, which perform different computing tasks based on how the light is manipulated. Those pulses, which are carrying information, keep going around and around the circuit during this function. The system represents a much more compact and efficient version of other quantum computing systems.

“We’ll start work to develop the hardware, now that we’ve resolved all problems except how to make a scheme that automatically corrects a calculation error,” Akira Furusawa, one of the researchers, said, according to the Japan Times. He is a professor at the University of Tokyo along with his team member, Shuntaro Takeda.

The difference between regular computers and quantum computers is in their bits, their base data unit that they use to perform tasks. The computer you use at your desk has bits that have a value of either 0 or 1, and these bits with different values can be combined to represent different kinds of information. But a quantum computer’s bits — which are known as quantum bits or qubits — can have two different values at the same time, known as being in a superposition. If we were speaking in terms of values of 0 and 1, a qubit could have both of them at once.

However, scientists can use a number of things as qubits, like the particles of light called photons or an electron, the negatively charged particle that helps make up an atom. With a photon being used as a qubit, for example, the two values that the qubit holds would be related to the photon’s polarization; it could be either horizontally or vertically polarized. With an electron, the values would be related to its magnetic spin, the direction of its momentum.

Once the computer measures a qubit, that qubit commits to one of the two possible states. But if it is not being measured, it exists in the superposition and you don’t know which one of the two values will hold.

Being in that superposition is where the computer gets all its power, particularly when a bunch of qubits are together — it increases the number of combinations that can be made with the two different values when each bit can hold either value, rather than just one of them.

Quantum computers can move significantly faster than classical computers.

The two Japanese scientists who invented the new method of manipulating light to control a circuit are expanding on a previous system. According to the Japan Times, a few years ago Furusawa had worked on an optical quantum computing system that used hundreds of mirrors and lenses and just one light pulse. The new method, which is described in the journal Physical Review Letters, can use just one circuit with a million qubits to perform the same tasks as several of those systems hooked up to one another, so it makes more calculations in a more efficient manner than current systems.