The Fredkin gate takes us one step closer to quantum computers

By Steve Brachmann
April 9, 2016

Binary tunnelThe world of classical computing will cease to see the amazing leaps in technology which have typified the Information Age exploding across the world over the past few decades. The theory on computer development proffered by Moore’s Law, which holds that processor density doubles every two years, has limits in terms of miniaturization. There will come a time where transistors, which must be of a certain size to block electrons and complete processing jobs, cannot be miniaturized anymore, preventing computer processors from taking on additional processing density.

We’ve already covered here on IPWatchdog how major American tech giants are making large investments in growing their quantum computing divisions. Quantum computing, which addresses the shortcomings in designing computers according to classical physics, will be the next generation of computers. Thanks to a team of computer science researchers in Australia, we’re closer to the world’s first true quantum computer with the demonstration of the world’s first Fredkin gate.

In late March, reports came out that researchers from Griffith University and the University of Queensland demonstrated the Fredkin gate, also known as the controlled-SWAP gate. First conceived by American digital physicist Edward Fredkin, the Fredkin gate is designed to exchange values between qubits in a quantum computing system based on a value of a third qubit.

Qubits are the type of bits used in quantum computing and are able to be used in processing algorithms requiring a whole new order of processing magnitude; unlike classical bits, which can only be represented as 1 or 0, qubits can be 1 or 0 and also take a superposition allowing it to be either value simultaneously. One drawback to qubits is that they lose their superposition when the bit is observed, making it difficult to use superpositions for complex modeling algorithms. The Fredkin gate’s use of a third qubit for operations seems as though it would address this shortcoming.

The Fredkin gate is perhaps a foundational component to quantum computers, replacing circuits requiring five logic operations with circuitry which takes advantage of the quantum principle of entanglement, which holds that entangled qubits share the same value at all times even when separated across the universe. The entanglement of photons allowed the Australian researchers to create a Fredkin gate requiring fewer logic operations.

The creation of a working Fredkin gate is an answer to one of the problems vexing quantum computer development, which includes the high susceptibility of qubits to environmental factors. Recent research coming out of Florida State University (FSU), however, has led to the discovery of qubits which are less affected by magnetic interference. Scientists working at FSU’s National High Magnetic Field Laboratory were able to keep a holmium ion qubit suspended within tungsten carbide molecules working coherently for more than eight microseconds, long enough to perform computational tasks.

The Author

Steve Brachmann

Steve Brachmann is a freelance journalist located in Buffalo, New York. He has worked professionally as a freelancer for more than a decade. He writes about technology and innovation. His work has been published by The Buffalo News, The Hamburg Sun,,, Motley Fool and Steve also provides website copy and documents for various business clients and is available for research projects and freelance work.

Warning & Disclaimer: The pages, articles and comments on do not constitute legal advice, nor do they create any attorney-client relationship. The articles published express the personal opinion and views of the author as of the time of publication and should not be attributed to the author’s employer, clients or the sponsors of Read more.

Discuss this

There are currently 1 Comment comments.

  1. Joachim Martillo April 10, 2016 3:15 am

    Until quantum computers are easily programmable, they are not particularly useful except for physicists dealing with the “publish or die” syndrome.