Cosmology in the Laboratory: Defect Dynamics in Liquid Crystals
15 Mar 1991-Science (American Association for the Advancement of Science)-Vol. 251, Iss: 4999, pp 1336-1342
TL;DR: Experiments described here support the simple "one-scale" model for cosmic string evolution, as well as some qualitative predictions of string statistical mechanics.
Abstract: Liquid crystals are remarkably useful for laboratory exploration of the dynamics of cosmologically relevant defects. They are convenient to work with, they allow the direct study of the "scaling solution" for a network of strings, and they provide a model for the evolution of monopoles and texture. Experiments described here support the simple "one-scale" model for cosmic string evolution, as well as some qualitative predictions of string statistical mechanics. The structure of monopoles and their apparent cylindrical but not spherical symmetry is discussed. A particular kind of defect known as texture is described and is shown to have a dynamical instability—it can decay into a monopole-antimonopole pair. This decay process has been observed occurring in the liquid crystal, and studied with numerical simulations.
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TL;DR: In this paper, the authors give an overview of recent theoretical and experimental progress in the area of nonequilibrium dynamics of isolated quantum systems, particularly focusing on quantum quenches: the temporal evolution following a sudden or slow change of the coupling constants of the system Hamiltonian.
Abstract: This Colloquium gives an overview of recent theoretical and experimental progress in the area of nonequilibrium dynamics of isolated quantum systems There is particularly a focus on quantum quenches: the temporal evolution following a sudden or slow change of the coupling constants of the system Hamiltonian Several aspects of the slow dynamics in driven systems are discussed and the universality of such dynamics in gapless systems with specific focus on dynamics near continuous quantum phase transitions is emphasized Recent progress on understanding thermalization in closed systems through the eigenstate thermalization hypothesis is also reviewed and relaxation in integrable systems is discussed Finally key experiments probing quantum dynamics in cold atom systems are overviewed and put into the context of our current theoretical understanding
2,340 citations
Cites background from "Cosmology in the Laboratory: Defect..."
...Defect formation following a quench was first studied in the context of vortices in liquid crystals (Chuang et al., 1991)....
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TL;DR: The theory of phase-ordering dynamics that is the growth of order through domain coarsening when a system is quenched from the homogeneous phase into a broken-symmetry phase, with the emphasis on recent developments, is reviewed in this paper.
Abstract: The theory of phase-ordering dynamics that is the growth of order through domain coarsening when a system is quenched from the homogeneous phase into a broken-symmetry phase, is reviewed, with the emphasis on recent developments. Interest will focus on the scaling regime that develops at long times after the quench. How can one determine the growth laws that describe the time dependence of characteristic length scales, and what can be said about the form of the associated scaling functions? Particular attention will be paid to systems described by more complicated order parameters than the simple scalars usually considered, for example vector and tensor fields. The latter are needed, for example, to describe phase ordering in nematic liquid crystals, on which there have been a number of recent experiments. The study of topological defects (domain walls, vortices, strings and monopoles) provides a unifying framework for discussing coarsening in these different systems.
2,130 citations
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19 Nov 1994
TL;DR: Cosmic strings provide a bridge between the physics of the very small and the very large They are predicted by some unified theories of particle interactions If they exist, they may help to explain some of the largest-scale structures seen in the Universe today as mentioned in this paper.
Abstract: The topic of cosmic strings provides a bridge between the physics of the very small and the very large They are predicted by some unified theories of particle interactions If they exist, they may help to explain some of the largest-scale structures seen in the Universe today They are `topological defects' that may have been formed at phase transitions in the very early history of the Universe, analogous to those found in some condensed-matter systems --- vortex lines in liquid helium, flux tubes in type-II superconductors, or disclination lines in liquid crystals In this review, we describe what they are, why they have been hypothesized and what their cosmological implications would be The relevant background from the standard models of particle physics and cosmology is described in section 1 In section 2, we review the idea of symmetry breaking in field theories, and show how the defects formed are constrained by the topology of the manifold of degenerate vacuum states We also discuss the different types of cosmic strings that can appear in different field theories Section 3 is devoted to the dynamics of cosmic strings, and section 4 to their interaction with other fields The formation and evolution of cosmic strings in the early Universe is the subject of section 5, while section 6 deals with their observational implications Finally, the present status of the theory is reviewed in section 7
1,047 citations
TL;DR: Spontaneous symmetry breaking is explored in 87Rb spinor condensates, rapidly quenched across a quantum phase transition to a ferromagnetic state, and phase-sensitive in situ detection of spin vortices is demonstrated.
Abstract: A central goal in condensed matter and modern atomic physics is the exploration of quantum phases of matter--in particular, how the universal characteristics of zero-temperature quantum phase transitions differ from those established for thermal phase transitions at non-zero temperature. Compared to conventional condensed matter systems, atomic gases provide a unique opportunity to explore quantum dynamics far from equilibrium. For example, gaseous spinor Bose-Einstein condensates (whose atoms have non-zero internal angular momentum) are quantum fluids that simultaneously realize superfluidity and magnetism, both of which are associated with symmetry breaking. Here we explore spontaneous symmetry breaking in 87Rb spinor condensates, rapidly quenched across a quantum phase transition to a ferromagnetic state. We observe the formation of spin textures, ferromagnetic domains and domain walls, and demonstrate phase-sensitive in situ detection of spin vortices. The latter are topological defects resulting from the symmetry breaking, containing non-zero spin current but no net mass current.
746 citations
TL;DR: In this paper, the authors review the key ideas behind cosmology-condensed matter connection and propose new experiments which could probe heretofore unaddressed aspects of the topological defect formation process.
714 citations
Cites background or methods from "Cosmology in the Laboratory: Defect..."
...…" quench experiments which were recently carried out in superfluid helium (Hendry et al., 1994; Hendry et al., 1995) and in liquid crystals (Chuang et al., 1991; Yurke, 1995; Bowick et al., 1994) and to propose further experiments which can shed a new light on the heretofore unaddressed…...
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...They were the first system in which a version of the experiment suggested for superfluid He 4 was carried out (Chuang et al., 1991; Bowick et al., 1994)....
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...…detection of vortex lines—while not as straightforward as it is for defects in liquid crystals, where they are visible almost with a naked eye (Chuang et al., 1991; Bowick et al., 1994; Yurke, 1995)—is also relatively simple, as it relies on the well-tested techniques of second sound…...
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...Following such a phase transition large densities of topological defects (especially the string-like disclination lines) were detected and studied (Chuang et al., 1991; Bowick et al., 1994)....
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References
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TL;DR: In this article, the possible domain structures which can arise in the universe in a spontaneously broken gauge theory are studied, and it is shown that the formation of domain wall, strings or monopoles depends on the homotopy groups of the manifold of degenerate vacua.
Abstract: The possible domain structures which can arise in the universe in a spontaneously broken gauge theory are studied. It is shown that the formation of domain wall, strings or monopoles depends on the homotopy groups of the manifold of degenerate vacua. The subsequent evolution of these structures is investigated. It is argued that while theories generating domain walls can probably be eliminated (because of their unacceptable gravitational effects), a cosmic network of strings may well have been formed and may have had important cosmological effects.
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TL;DR: In this article, the possible domain structures which can arise in the universe in a spontaneously broken gauge theory are studied, and it is shown that the formation of domain wall, strings or monopoles depends on the homotopy groups of the manifold of degenerate vacua.
Abstract: The possible domain structures which can arise in the universe in a spontaneously broken gauge theory are studied. It is shown that the formation of domain wall, strings or monopoles depends on the homotopy groups of the manifold of degenerate vacua. The subsequent evolution of these structures is investigated. It is argued that while theories generating domain walls can probably be eliminated (because of their unacceptable gravitational effects), a cosmic network of strings may well have been formed and may have had important cosmological effects.
2,274 citations
TL;DR: In this article, the authors estimate the rate of anomalous electroweak baryon-number nonconserving processes in the cosmic plasma and find that it exceeds the expansion rate of the universe at T > (a few) × 102 GeV.
2,079 citations