Quantum computing Definition and 262 Threads

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. They are believed to be able to solve 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. Expansion is expected in the next few years as the field shifts toward real-world use in pharmaceutical, data security and other applications.Quantum computing began in 1980 when physicist Paul Benioff proposed a quantum mechanical model of the Turing machine. Richard Feynman and Yuri Manin later suggested that a quantum computer had the potential to simulate things a classical computer could not feasibly do. In 1994, Peter Shor developed a quantum algorithm for factoring integers with the potential to decrypt RSA-encrypted communications. Despite ongoing experimental progress since the late 1990s, most researchers believe that "fault-tolerant quantum computing [is] still a rather distant dream." In recent years, investment in quantum computing research has increased in the public and private sectors. On 23 October 2019, Google AI, in partnership with the U.S. National Aeronautics and Space Administration (NASA), claimed to have performed a quantum computation that was infeasible on any classical computer.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, whether quantum logic gates, quantum annealing, or adiabatic quantum computation. 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.

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  1. L

    How to use Quantum computing language (qcl5.0.)

    Can you show me how to use quantum computing language ? I have download qcl6.0 but i don't know how to use it ?:confused: and have you know any solfware can simulate quantum structure ? :biggrin: help me if you can
  2. C

    Nanotechnology and Quantum Computing

    Where do these fields overlap (if at all) and where do they differ? If one was doing Nanotechnology at the graduate level with a BSc in physics behind them, what kinds of courses would one be taking? What about for Quantum Computing?
  3. W

    Quantum Computing Simulation: Possibilities & Limitations

    Is it theoretically possible to simulate a quantum computer by a real one (ie a Turing machine equivalent) even approximately? Any comments? Sorry if this has already been discussed. :confused:
  4. S

    Quantum Computing Research: Find Info for School Report

    i have to do a report on quantum computing for school, and i was wondering if anyone knew any good places to find it
  5. S

    Top Quantum Computing Topics for Beginners | Expert Suggestions

    I am interested in quantum computing, but presently have no clue as to where should I start. Could you suggest some topics in the field for me to go ? Some simple ones that I can finish them in one year ? Could you ? Thanks a lot
  6. S

    Quantum Computing: What It Is & What It Can Do

    What is a quantum computer in short ? what does it look like ? Can it be as fast as a present super computer ? Another, beside crypto, what can quantum algorithms do ? Can they do something good like genetic algorithms ? :redface:
  7. B

    Programs Exploring Quantum Computing: Top Universities for Postgraduate Studies

    Hi Does anyone know which universities in england and US do post graduate study in Quantum Computing? Raj
  8. L

    Building the World's First Quantum Computer: Challenges & Ideas

    I have read with interest the previous post on this topic, but wonder, I recently read an article about the first quantum transistor, a small step on the path to a true quantum computer, and also some articles on using argon atoms and electrons as ram and a bus respectively; can anyone however...
  9. marcus

    Spin networks and quantum computing (curious link-up)

    this seems strange spin networks are the quantum states of gravity in one approach to it (LQG) this paper treats them as quantum computers I cannot tell if ...I can't tell anything about this. some remarkable diagrams way at the end, and nice numbers like the Catalan numbers...
  10. B

    What are the main algorithms used in quantum computing?

    I've been asked to take part in a project invloving reasearch into Q.C I've basically got to investigate algorithms and i was wondering which are the main algorithms that have been devloped? So far I have Shor's factoring, Grover's searching and Discrete Logarithm algorithms.. Are there any...
  11. M

    What Major Should You Choose for a Career in Quantum Computing Research?

    What is the best major for someone who wants to get into the field of quantum computing research? Right now I'm a sophmore doing Electrical Engineering with a minor in Computer Science. Is this the right path? Do I need to specialize in a master's degree program or somthing of the sort...
  12. C

    Quantum Computing and Entanglement

    This is probably not the best site to get scientific information from, but still: http://computer.howstuffworks.com/quantum-computer1.htm I don't understand the final bit - how does entanglement allow scientists to know the value of the qubits? I can understand how it could allow them to...
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