Before the dream of quantum computing is realized, a number of inherent problems must first be solved. One of these is the ability to maintain a stable memory system that overcomes the intrinsic instability of the basic unit of information in quantum computing – the quantum bit or “qubit”. To address this problem, Physicists working at the University of California Berkeley (UC Berkeley) claim to have created breakthrough circuitry that continuously self-checks for inaccuracies to consistently maintain the error-free status of the quantum memory.
Vulnerability to environmentally-induced error – such as cosmic ray events or simply an unknown collapse of quantum coherence, for example – means that the information contained in a qubit is easily lost. And because of the nature of of quantum entanglement required to encode the qubit in the first place, any attempt to replicate the information will also immediately destabilize it.
“One of the biggest challenges in quantum computing is that qubits are inherently faulty,” said Julian Kelly, graduate student researcher at the John Martini physics lab at UC Berkeley. “So if you store some information in them, they’ll forget it.” Rather than attempt to maintain the integrity of a qubit by, say, trapping it in an isotope of silicon, the UC Berkeley team has instead opted for an algorithm-based approach.
Unlike conventional computers, quantum computers do not use binary data storage (ones and zeroes), where a bit can be one of two states. Instead, quantum computers use what is known as “superpositioning,” where the data contained in a qubit can also be either 0 or 1 (or even both simultaneously if superdense coding is used), and may exist at any and all possible positions simultaneously, and in various dimensions.
For more detail: First-ever quantum device that detects and corrects its own errors