Quantum computing (QC) offers the possibility of super-fast execution of digital algorithms. QC is not so much a replacement for conventional computers as a replacement for today’s supercomputers. QC is expected to provide great value in commercial computing for applications such as pharmaceuticals design, stock price prediction, password cracking and for decrypting encrypted messages when the keys are unknown.
A Q-Bit carrying a value is a physical particle such as a photon that has acquired one of those value states. The quantum mechanics concepts of “entanglement” and “superposition,” plus logic, are used to specify data values and algorithms that are subjected to computations which lead to a solving problem. In QC, Q-Bits are used instead of binary bits. Q-Bits carry states of value representing on, off, or both on and off. The ability to carry multiple values is called superposition.
Another weird attribute of these particles is their “entanglement” with another similar particle at a great distance. For example, if the state of a photon is altered here, then the state of its entangled particle a great distance away can alter in a like manner. Distance does not seem to matter. In effect, the alteration moves at a speed greater than the speed of light. That caused Albert Einstein to describe entanglement as “spooky action at a distance.”
Measurement of the value the state holds can cause the state to change in value. Extra cautions need to be taken to avoid value instability, so that errors are not introduced into the computations. Circuitry to stabilize the Q-Bit’s state adds to the complexity needed in the quantum computer’s design. Programming a QC requires the thinking of an electronic engineer who would be comfortable pushing Q-Bits through quantum logic gates.
So far, QC computers with as few as 5 Q-Bits to 50 Q-Bits have been constructed. These have been called Noisy Intermediate Scale Quantum (NISQ) computers, due to the instability of the Q-Bit values (i.e. noise in the results). Google, Microsoft, IBM, Amazon and Intel have built QCs of varying scales. Each is trying to establish a dominant position in a corner of the QC field. By 2020, NISQ computers will be available for commercial use on tasks that involve relatively few variables and probably using iterative algorithms. We will need to wait until the 2030s before general purpose QCs will be available in the marketplace.
There are many applications for which QC is more suited than classical computers. Lockheed Martin plans to use QC for autopilot software that is currently too complex for ordinary computers to handle. Google is using a quantum computer to design software that can distinguish cars from landmarks. Chemical reactions are quantum in nature as they form highly entangled quantum superposition states; however, fully developed quantum computers would not have any difficulty evaluating even the most complex processes.
The U.S. Air Force regards quantum technology as “disruptive in data security and GPS navigation. QC is one area where the Pentagon worries that it is playing catchup while China continues to leap ahead.” The technology is being developed for many civilian applications, and the military sees it as potentially game-changing for information and space warfare.
Interest in QCs will not dwindle in the cyber security field. The prospect of enemies using QC to crack our encrypted messages will have the intelligence and military technicians busy around the clock.
Quantum computing may take years to arrive, but it will be worth the wait.