When you first stumble across the term “quantum computer,” you might pass it off as some far-flung science fiction concept rather than a serious current news item.
But with the phrase being thrown around with increasing frequency, it’s understandable to wonder exactly what quantum computers are, and just as understandable to be at a loss as to where to dive in. Here’s the rundown on what quantum computers are, why there’s so much buzz around them, and what they might mean for you.
What is quantum computing, and how does it work?
All computing relies on bits, the smallest unit of information that is encoded as an “on” state or an “off” state, more commonly referred to as a 1 or a 0, in some physical medium or another.
Most of the time, a bit takes the physical form of an electrical signal traveling over the circuits in the computer’s motherboard. By stringing multiple bits together, we can represent more complex and useful things like text, music, and more.
All computing relies on bits, the smallest unit of information that is encoded as an “on” state or an “off” state, more commonly referred to as a 1 or a 0, in some physical medium or another.
Most of the time, a bit takes the physical form of an electrical signal traveling over the circuits in the computer’s motherboard. By stringing multiple bits together, we can represent more complex and useful things like text, music, and more.
The two key differences between quantum bits and “classical” bits (from the computers we use today) are the physical form the bits take and, correspondingly, the nature of data encoded in them. The electrical bits of a classical computer can only exist in one state at a time, either 1 or 0.
Quantum bits (or “qubits”) are made of subatomic particles, namely individual photons or electrons. Because these subatomic particles conform more to the rules of quantum mechanics than classical mechanics, they exhibit the bizarre properties of quantum particles. The most salient of these properties for computer scientists is superposition. This is the idea that a particle can exist in multiple states simultaneously, at least until that state is measured and collapses into a single state. By harnessing this superposition property, computer scientists can make qubits encode a 1 and a 0 at the same time.
The other quantum mechanical quirk that makes quantum computers tick is entanglement, a linking of two quantum particles or, in this case, two qubits. When the two particles are entangled, the change in state of one particle will alter the state of its partner in a predictable way, which comes in handy when it comes time to get a quantum computer to calculate the answer to the problem you feed it.
A quantum computer’s qubits start in their 1-and-0 hybrid state as the computer initially starts crunching through a problem. When the solution is found, the qubits in superposition collapse to the correct orientation of stable 1s and 0s for returning the solution.
What are the benefits of quantum computing?
Aside from the fact that they are far beyond the reach of all but the most elite research teams (and will likely stay that way for a while), most of us don’t have much use for quantum computers. They don’t offer any real advantage over classical computers for the kinds of tasks we do most of the time.
However, even the most formidable classical supercomputers have a hard time cracking certain problems due to their inherent computational complexity. This is because some calculations can only be achieved by brute force, guessing until the answer is found. They end up with so many possible solutions that it would take thousands of years for all the world’s supercomputers combined to find the correct one.
The superposition property exhibited by qubits can allow supercomputers to cut this guessing time down precipitously. Classical computing’s laborious trial-and-error computations can only ever make one guess at a time, while the dual 1-and-0 state of a quantum computer’s qubits lets it make multiple guesses at the same time.
So, what kind of problems require all this time-consuming guesswork calculation? One example is simulating atomic structures, especially when they interact chemically with those of other atoms. With a quantum computer powering the atomic modeling, researchers in material science could create new compounds for use in engineering and manufacturing. Quantum computers are well suited to simulating similarly intricate systems like economic market forces, astrophysical dynamics, or genetic mutation patterns in organisms, to name only a few.
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