MIT scientists may have created the first ever scalable quantum computer. They've created a quantum computer from five atoms in an ion trap that uses laser pulses to carry out Shor's algorithm on each atom to correctly factor the number 15.
But what is Shor's algorithm? This is a quantum algorithm that calculates the prime factors of a large number, vastly more efficiently than a classical computer. However, the algorithm's success depends on a computer with a large number of quantum bits. And while others have attempted to implement Shor's algorithm in various quantum systems, none have been able to do so with more than a few quantum bits in a scalable way.
Now, scientists have designed and built such a quantum computer. The system is designed in such a way that more atoms and lasers can be added to build a bigger and faster quantum computer that is able to factor much larger numbers. The results represent the first scalable implementation of Shor's algorithm.
"We show that Shor's algorithm, the most complex quantum algorithm known to date, is realizable in a way where, yes, all you have to do is go in the lab, apply more technology, and you should be able to make a bigger quantum computer," said Isaac Chuang, professor of electrical engineering and computer science at MIT. "It might still cost an enormous amount of money to build - you won't be building a quantum computer and putting it on your desktop anytime soon-but now it's much more an engineering effort and not a basic physics question."
Quantum computing relies on atomic-scale units, or "qubits," that can be simultaneously 0 and 1 - a state known as a superposition. In this state, a single qubit can essentially carry out two separate streams of calculations in parallel, making computations far more efficient than a classical computer.
In 2001, researchers designed a quantum computer based on one molecule that could be held in superposition and manipulated with nuclear magnetic resonance to factor the number 15. The results represented the first experimental realization of Shor's algorithm. Now, researchers have made this system scalable; the scientists used laser pulses to perform "logic gates" on four of five atoms. The results are then stored, forwarded, extracted and recycled via the fifth atom, carrying out Shor's algorithm in parallel.
The findings could be huge for quantum computing. In addition, it has implications for encryption, since quantum computers will, in theory, be able to unencrypt old secrets.
