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The video of an experiment showing vacuum fluctuations (in the red ring) amplified by spontaneous parametric down-conversion.. If the quantum field theory can be accurately described through perturbation theory, then the properties of the vacuum are analogous to the properties of the ground state of a quantum mechanical harmonic oscillator, or more accurately, the ground state of a measurement ...
In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics. [ 1 ] : xi QFT is used in particle physics to construct physical models of subatomic particles and in condensed matter physics to construct models of quasiparticles .
In quantum field theory, correlation functions, often referred to as correlators or Green's functions, are vacuum expectation values of time-ordered products of field operators. They are a key object of study in quantum field theory where they can be used to calculate various observables such as S-matrix elements.
In quantum field theory, a false vacuum [1] is a hypothetical vacuum state that is locally stable but does not occupy the most stable possible ground state. [2] In this condition it is called metastable. It may last for a very long time in this state, but could eventually decay to the more stable one, an event known as false vacuum decay.
The Savvidy vacuum is a model of the QCD vacuum which at a basic level is a statement that it cannot be the conventional Fock vacuum empty of particles and fields. In 1977, George Savvidy showed [ 12 ] that the QCD vacuum with zero field strength is unstable, and decays into a state with a calculable non vanishing value of the field.
The QED vacuum is subject to fluctuations about a dormant zero average-field condition; [4] Here is a description of the quantum vacuum: The quantum theory asserts that a vacuum, even the most perfect vacuum devoid of any matter, is not really empty.
This concept is important for working with correlation functions in quantum field theory. It is also important in spontaneous symmetry breaking. Examples are: The Higgs field has a vacuum expectation value of 246 GeV. [1] This nonzero value underlies the Higgs mechanism of the Standard Model.
In quantum field theory in curved spacetime, there is a whole class of quantum states over a background de Sitter space which are invariant under all the isometries: the alpha-vacua. Among them there is a particular one whose associated Green functions verify a condition (Hadamard condition) consisting to behave on the light-cone as in flat space.