Researchers have devised a new way to prevent neighboring quantum bits from interfering with each other, bringing large-scale quantum computing one step closer to reality.
Illustration by Jake Turcotte
Large-scale quantum computing, that is, leveraging the seemingly paradoxical behavior of subatomic particles to develop blazingly fast computers, is now one step closer to reality, now that scientists have found a way to better control how these particles behave.
Normal computers store information in binary digits, or bits. A bit can have only one of two values, most commonly represented by a 0 or a 1. Bits can be embodied in levers, punch cards, vacuum tubes, magnetic strips, tiny pits on compact discs, electrical capacitors, or any thing that can have two distinct states.
Quantum computers, by contrast, use quantum bits, or qubits, which arise out of the properties of elementary particles. At the atomic and subatomic scales, the rules seem to be different from those for larger objects. An electron, for instance, exists in more than one place at the same time. The same goes for the magnitude of its angular momentum, or "spin," which can have more than one value at the same time.
This behavior, called quantum superposition, allows qubits to have values of 0, 1, or both, all at the same time, creating the potential for computers that can carry out incredibly complex calculations in a fraction of the time that it would take a traditional computer. One of the most promising ways to create quantum computer chips is to use electrodes to control and harness the superposed spins of electrons bound to phosphorous atoms within silicon chips.
But researchers attempting to do this kept running into a problem: When you change the spin of one electron, you end up affecting the spin of the ones next to it. Think of it like a garage door opener that opens every garage on the street.