Many believe that quantum computers as practical tools for extremely complex predictive analysis are what we need to solve all those problems that today’s conventional computers can not. And it isn’t hard to understand why so much hope is being pinned on such computers who through their exceptional computing capabilities can solve hugely enormous, complex problems in a reasonable amount of time.
Classical computing makes use of ‘bits’ that can exist in either of two states — 0 or 1. On the other hand, quantum computing makes use of quantum bits (qubits for short) which can exist in more than one state — 0, 1, or 0 and 1 at the same time through those weird quantum concepts known as superpositioning and entanglement.
It is this capability of being in two states at once that gives quantum computers their extraordinary computing power. The question is: how fast can a quantum computer actually do its calculations? According to theorist Stephen Jordan of the National Institute of Standards and Technology (NIST), it will be extremely fast, of course. And contrary to what has been believed, there aren’t as many speed limitations as previously thought.
Jordan’s findings — which he describes as a ‘thought experiment’ — has to do with how fast the switches in a PC’s processor can flip from one state to another. In terms of conventional computers, that flipping is equivalent to the ‘clock speed’ of its processors. When it comes to quantum computers, it’s the qubits which function as switches. And based on what we know about physics and quantum mechanics, the rate at which a qubit can flip (or change from one state to another) is dependent and limited by the amount of energy it has.
While Jordan believes there may be some truth to this limitation, he has his doubts too. He says that though it’s logical for ‘switches’ to ‘flip’ more times as more logic operations are performed, with the inherent weirdness of the quantum world, the same shouldn’t necessarily hold true for quantum computers. He also notes that with the right design, ‘the computer could perform an arbitrarily large number of logic operations while only hopping through a constant number of distinct states.’ This would suggest that the number of logic operations carried out per second might in fact be bigger than the rate at which qubits can be flipped. This also implies that the speed of a quantum computer isn’t limited by energy.
If this is true, then it would mean that quantum computers are even more incredible than what we imagine them to be, making us believe that the hype about these machines being perhaps the solution to humanity’s most critical problems – cure disease or end war – does have reasonable basis. Think about it, quantum computers have the ability to whizz through calculations that would take a classical computer billions of years, or consume only seconds instead of years to break the encryption currently used to send secure online communications. Additionally, quantum computing is enabling scientific breakthroughs in business and science and solve problems that were previously unsolvable. That’s basically the power that a machine using quantum rules has, in a nutshell.
To be clear, Jordan isn’t saying that the speed at which a quantum computer can calculate isn’t limitless. He simply argues that it isn’t the availability of energy that’s limiting its speed.
Jordan’s work was recently published through the journal ‘Physical Review A‘ under the title ‘Fast quantum computation at arbitrarily low energy’.