All computing systems rely on a fundamental ability to store and manipulate information. Current computers manipulate individual bits, which store information as binary 0 and 1 states. Quantum computers leverage quantum mechanical phenomena to manipulate information. To do this, they rely on quantum bits, or qubits.
In contrast, a quantum computer employs quantum bits, or qubits, that can be both 0 and 1 at the same time, the equivalent of you sitting at both ends of your couch at once.
Mapping a qubit
Whereas an ordinary bit must be either 0 or 1, a qubit can be in any combination of 0 and 1 at the same time. Those two parts of the state mesh in a way described by an abstract angle, or phase. So the qubit’s state is like a point on a globe whose latitude reveals how much the qubit is 0 and how much it is 1, and whose longitude indicates the phase. Noise can jostle the qubit in two basic ways that knock the point around the globe.
Three quantum mechanical properties — superposition, entanglement, and interference — are used in quantum computing to manipulate the state of a qubit.
Superposition refers to a combination of states we would ordinarily describe independently. To make a classical analogy, if you play two musical notes at once, what you will hear is a superposition of the two notes.
Entanglement is a famously counter-intuitive quantum phenomenon describing behaviour we never see in the classical world. Entangled particles behave together as a system in ways that cannot be explained using classical logic.
3. Interference Finally, quantum states can undergo interference due to a phenomenon known as phase. Quantum interference can be understood similarly to wave interference; when two waves are in phase, their amplitudes add, and when they are out of phase, their amplitudes cancel.
Google’s claim on Quantum Computers
Google said that it had achieved a long-sought breakthrough called “quantum supremacy,” which could allow new kinds of computers to do calculations at speeds that are inconceivable with today’s technology.
A quantum machine could one day drive big advances in areas like artificial intelligence and make even the most powerful supercomputers look like toys. The Google device did in 3 minutes 20 seconds a mathematical calculation that supercomputers could not complete in under 10,000 years, the company said in its paper.
Facts about Quantum Computing
- Quantum computing is often described as “natural”. This is because although we don’t completely understand them, the mechanisms underpinning the real world (which have evolved through nature) clearly operate at a sub-atomic level. By simulating this with computers, we come a huge step closer to being able to simulate the natural world.
- At a quantum level, science fiction appears to become reality. Particles can travel backward or forwards in time and teleport (quantum tunnelling) between two positions.
- One possible explanation for why quantum computers work involves parallel universes. It has been theorised that qubits are able to exist in two states simultaneously because we are observing them in multiple universes simultaneously.
- Jeremy O’Brien, physicist and professorial research fellow at the University of Bristol: “In less than 10 years quantum computers will begin to outperform everyday computers, leading to breakthroughs in artificial intelligence, the discovery of new pharmaceuticals and beyond. The very fast computing power given by quantum computers has the potential to disrupt traditional businesses and challenge our cyber security.”