# Quantum-computing definition

A computer architecture based on quantum mechanics, the science of atomic structure and function. In the late 1990s, the feasibility of such a computer was demonstrated by MIT, the University of California at Berkeley and Stanford University. See quantum mechanics.

**The Computations Can Be Staggering**There are many problems that bog down even the fastest supercomputers because the number of computations are so staggering. The traveling salesman route is a classic example that seeks to find the most efficient round trip between cities. With 50 cities, the number of possible routes is 63 digits long. Whereas "classical" (non-quantum) computers may take days or even months to solve problems such as these, quantum computers are expected to come up with answers in mere minutes or seconds. See binary values and rice and chessboard legend.**Qubit Superposition and Entanglement**Quantum computing uses the "qubit," or quantum bit, comprising one or more electrons, and there are various approaches to their design. Quantum superposition is the condition that allows a qubit to be a 0 and 1 at the same time (see qubit). Entanglement is the property that allows one particle to relate to another over distance.Quantum annealing and gate model are the two major categories of quantum computers, and there is a lot of rivalry between them.**Quantum Annealing**D-Wave Systems in Canada offers the only commercial "quantum annealing" computer on the market. D-Wave computers are huge, refrigerated machines with up to 2,000 qubits that are used for optimization problems such as scheduling, financial analysis and medical research. Annealing is used to find the optimum route or the most efficient combination of settings to solve a problem.**Gate Model**Unlike the annealing method, gate model quantum computers use gates similar in concept to classical computers but with vastly different logic and entirely different architecture. Several companies are developing gate model machines, each with different qubit designs. The gates are actually created in real time by sending microwave pulses to the qubits. Gate model computers are expected to be able to factor huge numbers and should be able to crack cryptographic keys in a matter of seconds. This has foreboding implications if an attacker or enemy gains access to the technology.**IBM Q Experience in the Cloud**In 2016, IBM made a 5-qubit gate model quantum computer available in the cloud to allow scientists the opportunity of experimenting with gate model programming. A year later, the open source Qiskit development kit and a second machine with 16 qubits were added. The IBM Q Experience includes a library of educational materials.**A Lot Different Than Classical Computing**Inventing quantum hardware is a whole lot different than ordinary computers. The algorithms for solving real-world problems must be invented first, because new algorithms influence the design of the next generation of quantum architecture. There are hurdles to overcome with both annealing and gate model methods. However, scientists believe everyday quantum computing is just a matter of time. See also quantum cryptography.(computing) The use of quantum mechanical phenomena to transcend classical time complexity limitations in computing.

Quantum computing has the potential to break many previously unbreakable forms of encryption.

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