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quantum and computing
This technique is the most widespread method of computing amplitudes in quantum field theory today.
In quantum computing, a quantum bit or qubit is a quantum system that can exist in superposition of two bit values, " true " and " false ".
These newer concerns are among the many factors causing researchers to investigate new methods of computing such as the quantum computer, as well as to expand the usage of parallelism and other methods that extend the usefulness of the classical von Neumann model.
See the discussion on the relationship between key lengths and quantum computing attacks at the bottom of this page for more information.
The two best known quantum computing attacks are based on Shor's algorithm and Grover's algorithm.
According to Professor Gilles Brassard, an expert in quantum computing: " The time needed to factor an RSA integer is the same order as the time needed to use that same integer as modulus for a single RSA encryption.
Mainstream symmetric ciphers ( such as AES or Twofish ) and collision resistant hash functions ( such as SHA ) are widely conjectured to offer greater security against known quantum computing attacks.
* A discussion on how much time we have available before we must take steps to protect against quantum computing attacks
He believes that topological quantum computing is about to revolutionize computer science, and hopes that his teaching will help his students to understand its principles.
Since its inception it has broadened to find applications in many other areas, including statistical inference, natural language processing, cryptography, neurobiology, the evolution and function of molecular codes, model selection in ecology, thermal physics, quantum computing, plagiarism detection and other forms of data analysis.
Many areas of mathematics and computer science have been brought to bear on the problem, including elliptic curves, algebraic number theory, and quantum computing.
It was stated by Wootters, Zurek, and Dieks in 1982, and has profound implications in quantum computing and related fields.
Error correction is vital for practical quantum computing, and for some time this was thought to be a fatal limitation.
In 1995, Shor and Steane revived the prospects of quantum computing by independently devising the first quantum error correcting codes, which circumvent the no-cloning theorem.
* Orion quantum computing system
While this is extremely easy to implement on sufficiently simple theories, there are many situations where other methods of quantization yield more efficient procedures for computing quantum amplitudes.
The field of quantum computing was first introduced by Richard Feynman in 1982.
Although quantum computing is still in its infancy, experiments have been carried out in which quantum computational operations were executed on a very small number of qubits ( quantum bits ).
Both practical and theoretical research continues, and many national government and military funding agencies support quantum computing research to develop quantum computers for both civilian and national security purposes, such as cryptanalysis.

quantum and charge
In particle physics, antimatter is material composed of antiparticles, which have the same mass as particles of ordinary matter but have opposite charge and quantum spin.
Bader has demonstrated that these empirically useful models are connected with the topology of the quantum charge density.
In some contexts it is meaningful to speak of fractions of a charge ; for example in the charging of a capacitor, or in the fractional quantum Hall effect.
Unlike the electrically neutral photon of quantum electrodynamics ( QED ), gluons themselves carry color charge and therefore participate in the strong interaction in addition to mediating it, making QCD significantly harder to analyze than QED.
Like all subatomic particles, hadrons are assigned quantum numbers corresponding to the representations of the Poincaré group: J < sup > PC </ sup >( m ), where J is the spin quantum number, P the intrinsic parity ( or P-parity ), and C, the charge conjugation ( or C-parity ), and the particle's mass, m. Note that the mass of a hadron has very little to do with the mass of its valence quarks ; rather, due to mass – energy equivalence, most of the mass comes from the large amount of energy associated with the strong interaction.
Paul Dirac observed in 1931 that, because electricity and magnetism show a certain symmetry, just as quantum theory predicts that individual positive or negative electric charges can be observed without the opposing charge, isolated South or North magnetic poles should be observable.
Using quantum theory Dirac showed that if magnetic monopoles exist, then one could explain the quantization of electric charge --- that is, why the observed elementary particles carry charges that are multiples of the charge of the electron.
In 1972 he and Harald Fritzsch introduced the conserved quantum number " color charge ", and later along with Heinrich Leutwyler, they introduced quantum chromodynamics ( QCD ) as the gauge theory of the strong interaction ( cf.
Schrödinger himself initially did not understand the fundamental probabilistic nature of quantum mechanics, as he thought that the absolute square of the wave function of an electron should be interpreted as the charge density of an object smeared out over an extended, possibly infinite, volume of space.
* Quantum dot charge based semiconductor quantum computer ( qubit is the position of an electron inside a double quantum dot )
The three kinds of charge in QCD ( as opposed to one in quantum electrodynamics or QED ) are usually referred to as " color charge " by loose analogy to the three kinds of color ( red, green and blue ) perceived by humans.
For example, in quantum electrodynamics, these parameters are the charge and mass of the electron, as measured at a particular energy scale.
The theory of quantum chromodynamics explains that quarks carry what is called a color charge, although it has no relation to visible color.
In the context of quantum field theory, the indefinite density is understood to correspond to the charge density, which can be positive or negative, and not the probability density.
where is the quantum efficiency ( the conversion efficiency of photons to electrons ) of the detector for a given wavelength, is the electron charge, is the frequency of the optical signal, and is Planck's constant.
With q as the electronic charge, is the wavelength of interest, h is Planck's constant, c is the speed of light, k is Boltzmann's constant, T is the temperature of the detector, is the zero-bias dynamic resistance area product ( often measured experimentally, but also expressible in noise level assumptions ), is the quantum efficiency of the device, and is the total flux of the source ( often a blackbody ) in photons / sec / cm².
# in the other it corresponds to a probability distribution — specifically, the probability that the quantum of charge is located at any particular point within spatial dimensions.
However all other conserved quantum numbers ( angular momentum, electric charge, lepton number ) of the produced particles must sum to zero thus the created particles shall have opposite values of each other.
The laws of electromagnetism ( both classical and quantum ) are invariant under this transformation: if each charge q were to be replaced with a charge − q and the directions of the electric and magnetic fields were reversed, the dynamics would preserve the same form.

quantum and qubit
The Bloch sphere is a representation of a qubit, the fundamental building block of quantum computers.
A single qubit can represent a one, a zero, or, crucially, any quantum superposition of these two qubit states ; moreover, a pair of qubits can be in any quantum superposition of 4 states, and three qubits in any superposition of 8.
* Superconductor-based quantum computers ( including SQUID-based quantum computers ) ( qubit implemented by the state of small superconducting circuits ( Josephson junctions ))
* Trapped ion quantum computer ( qubit implemented by the internal state of trapped ions )
* electrically defined or self-assembled quantum dots ( e. g. the Loss-DiVincenzo quantum computer or ) ( qubit given by the spin states of an electron trapped in the quantum dot )
* Solid-state NMR Kane quantum computers ( qubit realized by the nuclear spin state of phosphorus donors in silicon )
* Electrons-on-helium quantum computers ( qubit is the electron spin )
* Cavity quantum electrodynamics ( CQED ) ( qubit provided by the internal state of atoms trapped in and coupled to high-finesse cavities )
* Fullerene-based ESR quantum computer ( qubit based on the electronic spin of atoms or molecules encased in fullerene structures )
* Diamond-based quantum computer < ref name =" Nizovtsevetal2004 "> ( qubit realized by the electronic or nuclear spin of Nitrogen-vacancy centers in diamond )
* Rare-earth-metal-ion-doped inorganic crystal based quantum computers ( qubit realized by the internal electronic state of dopants in optical fibers )
The most popular unit of quantum information is the qubit, a two-level quantum system.
A two-level quantum system can carry at most one qubit, in the same sense a classical binary digit can carry at most one classical bit.

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