Quantum Computing

Quantum computing is a type of computation that harnesses the collective properties of quantum states, such as superposition, interference, and entanglement, to perform calculations. The devices that perform quantum computations are known as quantum computers. Though current quantum computers are too small to outperform usual (classical) computers for practical applications, they are believed to be capable of solving certain computational problems, such as integer factorization (which underlies RSA encryption), substantially faster than classical computers. The study of quantum computing is a subfield of quantum information science.

There are several types of quantum computers (also known as quantum computing systems), including the quantum circuit model, quantum Turing machine, adiabatic quantum computer, one-way quantum computer, and various quantum cellular automata. The most widely used model is the quantum circuit, based on the quantum bit, or "qubit", which is somewhat analogous to the bit in classical computation. A qubit can be in a 1 or 0 quantum state, or in a superposition of the 1 and 0 states. When it is measured, however, it is always 0 or 1; the probability of either outcome depends on the qubit's quantum state immediately prior to measurement.

Efforts towards building a physical quantum computer focus on technologies such as transmons, ion traps and topological quantum computers, which aim to create high-quality qubits. These qubits may be designed differently, depending on the full quantum computer's computing model, as to whether quantum logic gates, quantum annealing, or adiabatic quantum computation are employed. There are currently a number of significant obstacles to constructing useful quantum computers. It is particularly difficult to maintain qubits' quantum states, as they suffer from quantum decoherence and state fidelity. Quantum computers therefore require error correction.

Any computational problem that can be solved by a classical computer can also be solved by a quantum computer. Conversely, any problem that can be solved by a quantum computer can also be solved by a classical computer, at least in principle given enough time. In other words, quantum computers obey the Church–Turing thesis. This means that while quantum computers provide no additional advantages over classical computers in terms of computability, quantum algorithms for certain problems have significantly lower time complexities than corresponding known classical algorithms. Notably, quantum computers are believed to be able to quickly solve certain problems that no classical computer could solve in any feasible amount of time—a feat known as "quantum supremacy." The study of the computational complexity of problems with respect to quantum computers is known as quantum complexity theory.

Source: Quantum computing (wikipedia.org)

What is the quantum apocalypse and should we be scared?

Imagine a world where encrypted, secret files are suddenly cracked open - something known as "the quantum apocalypse". Put very simply, quantum computers work completely differently from the computers developed over the past century.

Quantum computer 'construction plan' drawn up

Physicists have drawn up construction plans for a large-scale quantum computer. These super-fast machines promise to revolutionise computing, harnessing the world of quantum mechanics to solve problems that are beyond reach for even the most advanced "classical" ones.

Quantum computers 'one step closer'

Quantum computing has taken a step forward with the development of a programmable quantum processor made with silicon. The team used microwave energy to align two electron particles suspended in silicon, then used them to perform a set of test calculations.

Google claims 'quantum supremacy' for computer

Google says an advanced computer has achieved "quantum supremacy" for the first time, surpassing the performance of conventional devices.

IBM claims advance in quantum computing

IBM has unveiled an advanced "quantum" processor that is part of an effort to build super-fast computers. These machines could revolutionise computing, harnessing the strange world of quantum physics to solve problems beyond reach for even the most advanced "classical" ones.

Microsoft-led team retracts quantum 'breakthrough'

The research claimed to have found evidence of an elusive subatomic particle Microsoft suggested could help the development of more powerful computers. But it now says mistakes were made.

Tricking the perfect code machine

They don't often pose for goofy photographs - the members of the Quantum Hacking group at the Norwegian University of Science and Technology (NTNU), and the Centre for Quantum Technologies at the National University of Singapore. But everyone wants their picture taken with Eve.

Team's quantum object is biggest by factor of billions

Researchers have created a "quantum state" in the largest object yet. Such states, in which an object is effectively in two places at once, have until now only been accomplished with single particles, atoms and molecules.

Quantum computing: Is it possible, and should you care?

What is a quantum computer and when can I have one? It makes use of all that "spooky" quantum stuff and vastly increases computing power, right? And they'll be under every desk when scientists finally tame the spooky stuff, right? And computing will undergo a revolution no less profound than the one

Quantum computing device hints at powerful future

One of the most complex efforts toward a quantum computer has been shown off at the American Physical Society meeting in Dallas in the US. It uses the strange "quantum states" of matter to perform calculations in a way that, if scaled up, could vastly outperform conventional computers.

Quantum computing could head to 'the cloud', study says

A novel high-speed, high-security computing technology will be compatible with the "cloud computing" approach popular on the web, a study suggests.Quantum computing will use the inherent uncertainties in quantum physics to carry out fast, complex computations.

Quantum computer slips onto chips

Researchers have devised a penny-sized silicon chip that uses photons to run Shor's algorithm - a well-known quantum approach - to solve a maths problem.

Quantum computing

Quantum computing is the exploitation of collective properties of quantum states, such as superposition and entanglement, to perform computation. The devices that perform quantum computations are known as quantum computers.

D-Wave Systems

D-Wave Systems Inc. is a Canadian quantum computing company, based in Burnaby, British Columbia, Canada. D-Wave was the world's first company to sell computers to exploit quantum effects in their operation.

Spin-based electronics gets boost

The next generation of computers may make use of the "spin" of electrons instead of their charge. Spintronics relies on manipulating these spins to make them capable of carrying data.

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