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Introduction To Quantum Mechanics Quantum mechanics Quantum mechanics is the science of the very small. It explains the behavior of matter and its interactions with energy on the scale of atoms and subatomic particles. By contrast, classical physics only explains matter and energy on a scale familiar to human experience, including the behavior of astronomical bodies such as the Moon. Classical physics Classical physics is still used in much of modern science and technology [...More...]  "Introduction To Quantum Mechanics" on: Wikipedia Yahoo 

Qubit In quantum computing, a qubit (/ˈkjuːbɪt/) or quantum bit (sometimes qbit) is a unit of quantum information—the quantum analogue of the classical binary bit. A qubit is a twostate quantummechanical system, such as the polarization of a single photon: here the two states are vertical polarization and horizontal polarization. In a classical system, a bit would have to be in one state or the other [...More...]  "Qubit" on: Wikipedia Yahoo 

Vacuum State In quantum field theory, the quantum vacuum state (also called the quantum vacuum or vacuum state) is the quantum state with the lowest possible energy. Generally, it contains no physical particles. Zeropoint field is sometimes used as a synonym for the vacuum state of an individual quantized field. According to presentday understanding of what is called the vacuum state or the quantum vacuum, it is "by no means a simple empty space".[1][2] According to quantum mechanics, the vacuum state is not truly empty but instead contains fleeting electromagnetic waves and particles that pop into and out of existence.[3][4][5] The QED vacuum QED vacuum of quantum electrodynamics (or QED) was the first vacuum of quantum field theory to be developed [...More...]  "Vacuum State" on: Wikipedia Yahoo 

Quantum Foam Quantum foam (also referred to as spacetime foam) is a concept in quantum mechanics devised by John Wheeler in 1955.[1]Contents1 Background 2 Experimental results2.1 Constraints and limits2.1.1 Random diffusion model 2.1.2 Holographic model3 Relation to other theories 4 See also 5 Notes 6 ReferencesBackground[edit] With an incomplete theory of quantum gravity, it is impossible to be certain what spacetime would look like at small scales. However, there is no reason that spacetime needs to be fundamentally smooth [...More...]  "Quantum Foam" on: Wikipedia Yahoo 

Quantum Fluctuation In quantum physics, a quantum fluctuation (or vacuum state fluctuation or vacuum fluctuation) is the temporary change in the amount of energy in a point in space,[1] as explained in Werner Heisenberg's uncertainty principle. This allows the creation of particleantiparticle pairs of virtual particles. The effects of these particles are measurable, for example, in the effective charge of the electron, different from its "naked" charge. Quantum fluctuations may have been very important in the origin of the structure of the universe: according to the model of expansive inflation the ones that existed when inflation began were amplified and formed the seed of all current observed structure [...More...]  "Quantum Fluctuation" on: Wikipedia Yahoo 

Quantum Noise In physics, quantum noise refers to the uncertainty of a physical quantity that is due to its quantum origin. In certain situations, quantum noise appears as shot noise; for example, most optical communications use amplitude modulation, and thus, the quantum noise appears as shot noise only. For the case of uncertainty in the electric field in some lasers, the quantum noise is not just shot noise; uncertainties of both amplitude and phase contribute to the quantum noise. This issue becomes important in the case of noise of a quantum amplifier, which preserves the phase [...More...]  "Quantum Noise" on: Wikipedia Yahoo 

Spin (physics) In quantum mechanics and particle physics, spin is an intrinsic form of angular momentum carried by elementary particles, composite particles (hadrons), and atomic nuclei.[1][2] Spin is one of two types of angular momentum in quantum mechanics, the other being orbital angular momentum. The orbital angular momentum operator is the quantummechanical counterpart to the classical angular momentum of orbital revolution: it arises when a particle executes a rotating or twisting trajectory (such as when an electron orbits a nucleus).[3][4] The existence of spin angular momentum is inferred from experiments, such as the Stern–Gerlach experiment, in which particles are observed to possess angular momentum that cannot be accounted for by orbital angular momentum alone.[5] In some ways, spin is like a vector quantity; it has a definite magnitude, and it has a "direction" (but quantization makes this "direction" different from the direction of an ordinary vector) [...More...]  "Spin (physics)" on: Wikipedia Yahoo 

Quantum System A quantum system is a portion of the whole Universe Universe (environment or physical world) which is taken under consideration to make analysis or to study for quantum mechanics pertaining to the waveparticle duality in that system. Everything outside this system (i.e. environment) is studied only to observe its effects on the system. A quantum system involves the wave function and its constituents, such as the momentum and wavelength of the wave for which wave function is being defined. See also[edit]Quantum Twostate quantum system Nonlinear system Dynamical system Thermodynamic system Physical system Quantum state Quantum number Ground state Excited state Energy levels Degenerate energy levelsThis quantum mechanicsrelated article is a stub [...More...]  "Quantum System" on: Wikipedia Yahoo 

Symmetry Breaking This article needs attention from an expert in Physics. Please add a reason or a talk parameter to this template to explain the issue with the article. WikiProject Physics Physics may be able to help recruit an expert. (May 2014)A ball is initially located at the top of the central hill (C). This position is an unstable equilibrium: a very small perturbation will cause it to fall to one of the two stable wells left (L) or (R). Even if the hill is symmetric and there is no reason for the ball to fall on either side, the observed final state is not symmetric.In physics, symmetry breaking is a phenomenon in which (infinitesimally) small fluctuations acting on a system crossing a critical point decide the system's fate, by determining which branch of a bifurcation is taken. To an outside observer unaware of the fluctuations (or "noise"), the choice will appear arbitrary [...More...]  "Symmetry Breaking" on: Wikipedia Yahoo 

Spontaneous Symmetry Breaking Spontaneous symmetry breaking Spontaneous symmetry breaking is a spontaneous process of symmetry breaking, by which a physical system in a symmetric state ends up in an asymmetric state.[1][2][3] In particular, it can describe systems where the equations of motion or the Lagrangian obey symmetries, but the lowestenergy vacuum solutions do not exhibit that same symmetry. When the system goes to one of those vacuum solutions, the symmetry is broken for perturbations around that vacuum even though the entire Lagrangian retains that symmetry.Contents1 Overview 2 Examples [...More...]  "Spontaneous Symmetry Breaking" on: Wikipedia Yahoo 

Quantum Annealing Quantum annealing Quantum annealing (QA) is a metaheuristic for finding the global minimum of a given objective function over a given set of candidate solutions (candidate states), by a process using quantum fluctuations. Quantum annealing Quantum annealing is used mainly for problems where the search space is discrete (combinatorial optimization problems) with many local minima; such as finding the ground state of a spin glass.[1] It was formulated in its present form by T. Kadowaki and H. Nishimori (ja) in " Quantum annealing Quantum annealing in the transverse Ising model"[2] though a proposal in a different form had been made by A. B. Finilla, M. A. Gomez, C. Sebenik and J. D [...More...]  "Quantum Annealing" on: Wikipedia Yahoo 

Quantum Realm The quantum realm, also called the quantum scale, is a term of art in physics referring to scales where quantum mechanical effects become important when studied as an isolated system.[1][2][3] Typically, this means distances of 100 nanometers (10−9 meters) or less or at very low temperature. More precisely, it is where the action or angular momentum is quantized. While originating on the nanometer scale, such effects can operate on a macro level generating some paradoxes like in the Schrödinger's cat thought experiment. Two classical examples are electron tunneling and the doubleslit experiment. Most fundamental processes in molecular electronics, organic electronics and organic semiconductors also originate in the quantum realm. The quantum realm can also sometimes involve actions [...More...]  "Quantum Realm" on: Wikipedia Yahoo 

Quantum Levitation In quantum field theory, the Casimir effect Casimir effect and the Casimir–Polder force are physical forces arising from a quantized field [...More...]  "Quantum Levitation" on: Wikipedia Yahoo 

QCD Vacuum Th Quantum Chromodynamic Vacuum or QCD vacuum is the vacuum state of quantum chromodynamics (QCD). It is an example of a nonperturbative vacuum state[further explanation needed], characterized by nonvanishing condensates such as the gluon condensate and the quark condensate in the complete theory which includes quarks. The presence of these condensates characterizes the confined phase of quark matter.Unsolved problem in physics: QCD in the nonperturbative regime: confinement. The equations of QCD remain unsolved at energy scales relevant for describing atomic nuclei [...More...]  "QCD Vacuum" on: Wikipedia Yahoo 

QED Vacuum The Quantum Electrodynamic Vacuum or QED vacuum QED vacuum is the fieldtheoretic vacuum of quantum electrodynamics [...More...]  "QED Vacuum" on: Wikipedia Yahoo 

Photon Entanglement Photon Photon entanglement is a supplement to the article BohrEinstein debates and is designed to help clarify the discussion of the EinsteinPodolskyRosen argument in quantum theory which takes place in the previous article.Contents1 Entanglement 2 Applications 3 See also 4 References 5 External linksEntanglement[edit] A quantum system is described, at every instant, by a vector state which, according to the theory, represents the maximum amount of information that it is possible to have. To simplify discussion, taking the example of the state of polarization of a photon and associate with it the vector state 45 ⟩ displaystyle left45rightrangle The knowledge of the vector state, in fact, provides us exclusively with information on the possible results of measurements which we decide to carry out on the system [...More...]  "Photon Entanglement" on: Wikipedia Yahoo 