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What is quantum computing? Quantum computing uses specialized technology—including computer hardware and algorithms that take advantage of quantum mechanics—to solve complex problems that classical computers or supercomputers can't solve, or can't solve quickly enough.

Quantum computing sounds like the stuff of science fiction, yet, to some extent, it’s a reality. While it’s not certain when – or if – commercial machines will appear, Google and IBM, plus other tech giants and start-ups, are competing to build the first actually useful quantum device. To understand why the prospect of quantum computing is so compelling, we can start by looking at the limitations of conventional computing, and at how quantum computing avoids these limitations. Next, we can look at applications that would benefit particularly well from the technology – and at why it hasn’t yet translated into everyday, usable products.

The quantum concept is valuable because it allows for more than just two states. It relates to interactions between particles at a tiny scale, so small that the rules of physics as we normally experience them no longer apply. However, it is possible that some of the unusual – and counterintuitive - phenomena occurring at this level could be used to overcome the limitations of traditional computing.

In quantum computing, the smallest unit of data is not the bit, but the qubit, based on something like the spin of a magnetic field. Like a bit, this can be set to one of two states - 0 or 1 - but unlike a bit, it is not as simple as just being on or off. Thanks to the quirks of the quantum level, a qubit can also be in any proportion of both states, called a superposition. Sometimes, this is described as being both 0 and 1 simultaneously, although this isn't entirely accurate. Rather, it could be anywhere between completely 0 and completely 1 - but the catch is, as soon as we actually measure a qubit, it collapses into one of the two definite states.

While being difficult or impossible to fully understand, superposition means that the amount of data that can be stored grows exponentially as the number of qubits increases. A group of 20 qubits can hold more than a million values at once. However, quantum computing also involves further concepts, particularly quantum entanglement. This means that, unlike traditional computers that can only process data sequentially, quantum computers can process it all simultaneously.

2024-04-29 7Am Pratik Ghimire