Quantum Computing Just Grew Way the Hell Up

Five qubit quantum circuit. Image: Martinis Group/UCSB
Five qubit quantum circuit. Image: Martinis Group/UCSB
On Wednesday, researchers at the Joint Quantum Institute at the University of Maryland unveiled a first-of-its-kind fully programmable and reconfigurable quantum computer. The five-qubit machine, which is described in the journal Nature, represents a dramatic step toward general-purpose quantum computing—and, with it, an upending of what we can even consider to be computable.

By Michael Byrne | MOTHERBOARD

It’s often remarked rather abstractly that the rather abstract power of future quantum computers will nuke our most fundamental layer of digital security by virtue of their very existence. How will they do this? By being very powerful, goes the nigh-universal pop science answer. A very powerful computer, of the sort that has never been seen before, may use that great power to factor numbers much more quickly than could be accomplished using even non-quantum supercomputers. The RSA algorithm, which guards most of our digital data, is based on not being able to do this.

The mechanism behind this RSA crippling has had a name since 1994, one year before the very first quantum logic gate had even been realized at a NIST laboratory in Boulder, Colorado. It’s called Shor’s algorithm, and is a method of factoring very large whole numbers using quantum hardware. Like many quantum algorithms, it relies on a mathematical operation known as the quantum Fourier transform (QFT), which decomposes a given quantum state into its constituent parts.

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