The science of quantum mechanics, otherwise known as quantum field theory or a wave mechanical model, is not a time travel method as seen in the 1980s TV show, Quantum Leap. Neither is it technique to ‘phase’ through solid objects as seen in The Flash comic books. Despite the magical properties attributed to this branch of physics in pop culture, quantum mechanics is essentially the study of the strange behaviours of subatomic particles like electrons and photons in our universe.
In recent years though, the principles behind quantum mechanics have open the doors for the development of quantum computers, which, theoretically, would be thousands of times more powerful than modern supercomputers.
Classical computing is basically built on the concept of integrated circuits, which switches between the binary states of 1 and 0 to carry a single piece of information, called bit, defined by Boolean Algebra. By incorporating transistors into the process, a larger number of binary state shifts can be performed within an integrated circuit. Over time, the transistors became increasingly smaller before it was eventually built inside microprocessors.
By the time personal computers began to dominate the landscape, manufacturers like Intel and AMD have patented methods to create tiny microprocessors with huge numbers of tiny silicon transistors. With every new version, the number of transistors became exponentially larger. The current Intel Xeon 8181 processors, for instance, comes with approximately eight billion transistors, while Graphcore’s IPU(used in enterprise datacentres) is packed with a mind boggling 23.6 billion transistors.
However, there is a hard limit on the number of transistors which can be built inside processors. You can only reduce the size of transistors to a certain level based on current miniaturisation technology. This is before we even consider the data delivery, power requirement and heat management aspects. As such, the growth of classical computing power will always be incremental.
Principally, the biggest difference between quantum computing and classical computing lies in the absence of transistors. Instead, quantum computing relies on subatomic particles. Further, quantum computing does not rely on binary switches. Since subatomic particles can exist in more than a single state at a time (particles can literally leap out of existence between shifts in states), a superposition and entanglement of values can occur, allowing a far larger volume of information (known as qubits) to be defined through linear algebra over Hilbert space at any and every given instance.
Currently (as of 2019), no commercial quantum computers exists. There are probably prototypes being built around the world as we speak. However, scientists must still overcome challenges in hardware and software required to harness the potential of quantum computing. In fact, no one is even certain yet of the physical shape and size of quantum computer.
Nevertheless, quantum computers are not very far away. Google announced in 2017 that they are planning on commercialising quantum technology by 2022. NASA, meanwhile, spent $15 million in January 2019 to purchase an experimental quantum computer that reportedly has no product applications. Yes, NASA spent millions on a quantum computer which can’t be used for anything. On a far more positive note, IBM, Microsoft, Intel and a dozen other companies have reported varying levels of success in quantum computing hardware and software.
It will take a few more years still, - probably a decade before you can purchase one commercially – but when they are available, they will make existing personal computers look like pocket calculators in sheer computing power.