Written by Alyssa Walker

If any field of computing is outside the box it's quantum computing. It's theoretical and confusing. One grad student, though, has just answered an essential question in the field. The big discovery took her eight years. Let's take a closer look.

Urmila Mahadev, a PhD student at the University of California, Berkeley, spent eight years answering one of the most basic questions in quantum computation: How do you know whether a quantum computer has done anything quantum at all?

Simple question. Tough to answer.

In traditional computing, such as the device on which you are reading this, bits, the tiniest units of data, are binary -- they are at 1 or 0, on or off.

In quantum computing, units of data can be 1 or 0, or both at the same time in what's called a state of 'superposition'. They are called qubits, and they adopt the properties of quantum mechanics. 

According to a recent article in the Financial Times, Professor John Morton of University College London said, "With 50 qubits you can solve problems beyond the fastest supercomputers today. With 300, you would have more states than there are atoms in the universe."

Bottom line: they are tricky. It is unlikely that we will see quantum computers in the next decade. But they are exceedingly interesting and potentially very useful.

What did Mahadev do? In her second year of study with her advisor, Umesh Vazirani, she wanted to unlock the quantum computer's mysteries. She wanted to know if a quantum computer -- whose systems work beyond the scope of traditional computers --actually did what it was supposed to. 

In an article in Quanta Magazine, Vairani explained, “A quantum computer is very powerful, but it’s also very secretive."

Over her years of research, Mahadev designed an interactive protocol which allows users with no quantum powers to apply a cryptographic harness to a quantum computer and give it commands, with the certainty that the quantum computer is following their instructions. 

Vazirani explained that she found a way to give users "leverage that the computer just can't shake off."

Mahadev solved the problem by applying classic cryptography in the quantum realm --and computer scientists the world over are very excited about the breakthrough.

Learn more about computer science.

Alyssa Walker is a freelance writer, educator, and nonprofit consultant. She lives in the White Mountains of New Hampshire with her family.
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