The Very Strange — And Fascinating — Ideas Behind Quantum Computing

A 90 Year-Old Argument

In the early 20th century, one of the fundamental assumptions was an idea, sometimes known as Laplace’s demon, that the universe was perfectly deterministic. In other words, if you knew the precise location and momentum of every particle in the universe, you could calculate all of their past and future values. Every effect has a cause, or so it was thought.

A Geek Before Geeks Were Cool

Growing up in the quiet Westchester village of Croton-on-Hudson, about a half hour from IBM’s headquarters in Armonk NY, Bennett was, as he put it to me, “a geek before geeks were cool.” While other teenage boys were riding bikes and playing baseball, he usually had his head buried in a copy of Scientific American, wrapping himself in its world of crazy ideas.

A Witches Brew Of Crazy Ideas

As a graduate student, Bennett went to see a talk by an IBM scientist named Rolf Landauer and learned about his principle that if bits are not erased, then energy can be conserved. With his background in chemistry, Bennett was able to further Landauer’s work and make important breakthroughs in reversible computing. Bennett was soon thoroughly hooked on computing — and on IBM.

Einstein’s Last Stand

As noted above, Einstein could never bring himself to accept quantum mechanics, especially entanglement, because he thought that such “spooky action at a distance” violated the laws of physics. How could observing a particle in one place tell you about a particle in another place, without affecting it in some way?

A New Quantum Universe Of Computing

To understand how a quantum computer works, we first have to think about how a classical computer, sometimes known as a Turing machine, works. In essence, today’s computers transform long series of ones and zeros — called bits — into logical statements and functions according to a set of rules called Boolean logic.

We Are Entering A New Quantum Era

The ideas surrounding quantum computing are so strange that I must confess that while talking to Dr. Bennett, I sometimes wondered whether I had somehow wandered into a late night dorm room discussion that had gone on too long. As the legendary physicist Richard Feynman confessed, the ideas behind quantum mechanics are pretty hard to accept.



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Greg Satell

Greg Satell

Bestselling Author of Cascades and Mapping Innovation, @HBR Contributor, - Learn more at — note: I use Amazon Affiliate links for books.