Classical computers, the computers we use today, are basically computational machines that perform calculations in binary form. The Binary number system uses 0 and 1 as the only digits in the number system. At a more fundamental level, these zeros and ones represent electrical signals which could be high (1) or low (0). Every calculation that a classical computer performs is simply the manipulation of these binary numbers to produce the desired result.
For years since the development of the transistor, computing power has continued to improve according to Moore’s law. Moore’s law states that the number of transistors in a dense integrated double about every two years. This doubling of the number of transistors entails a doubling in the computing power in a form factor. Over time Moore’s law will come to an end and it seems we are fast approaching the end of this law. Some experts even predict that the law may die as soon as 2020.
Researchers have looked into ways of sustaining the continued improvement of computing capability way after Moore’s law has faded. This has resulted in the adoption of various paradigms that seek to provide better computational capacity than what can be offered by the current semiconductor chips.
Quantum mechanics is a branch of physics that seeks to describe at the smallest scales of energy levels of atoms and sub-atomic particles. This branch of physics has proved to be one of the leading candidates for the development of a new form of computing that will take us into the future.
IBM and D-Wave Systems are some of the companies at the forefront of the quantum computing revolution. IBM offers a publicly available and functional quantum computer that anyone can use and have a feel of what the future feels like. The computer is a 5 qubit computer.
How quantum computers work
Classical computers use bits (short for binary digits) as the basic units of information. This is why all forms of computer memory are measured in some multiples of these bits (Kilobytes, Megabytes, Terabytes, etc). One byte consists of a set of 8 bits. As mentioned earlier, a bit can either be a 1 or a 0. Quantum computers make use of what are known as qubits (short for quantum bits). A qubit is mysterious. It can take values of 0, 1 or both. At the scale of quantum mechanics, things become weird and very hard to explain, for example, a particle can be in two places at the same time. This behavior is known as superposition.
The weird behaviour exhibited by quantum particles makes it possible for quantum computers to make calculations that would otherwise take forever for classical computers to solve. Certain problems such as modeling chemical compounds, the tower of Hanoi, travelling sales man problem and other problems that are considered to NP-complete (the set of all decision problems whose solutions can be verified in polynomial time) cannot be solved by classical computers infinite time (or at least a reasonable amount of time). Quantum computers will bring a dramatic shift in the way computers to solve such problems and will actually be able to solve some of these problems.
A quantum computer that is powerful enough could break the encryption algorithms that are used to secure online transactions and passwords online in a matter of hours or even minutes. Specialists say that a 50 qubit quantum computer will be powerful enough to be able to solve most of the encryption algorithms that are in use today and will thus render the entire internet insecure. A 50 qubit quantum computer will also open up other areas that humanity has struggled with for centuries.
When can we expect a 50 qubit quantum computer?
A 50 qubit quantum computer seems very much plausible but quantum computer are very difficult to make and maintain. This is due to decoherence. A quantum system cannot stay in a coherent state for a long time. The conditions under which these computers are meant to work are also very difficult to maintain. The most common type of quantum computer uses particles that are supercooled to near absolute zero temperatures and these temperatures are difficult to maintain. As a result of all these and other factors, quantum computers that will bring massive disruption to the current state of affairs are still very far off into the future.