Nearly perfect fluidity: from cold atomic gases to hot quark gluon plasmas
By T. Schaefer, D. Teaney. 2009
341 citations recorded by the source corpus.
Shear viscosity is a measure of the amount of dissipation in a simple fluid. In kinetic theory shear viscosity is related to the rate of momentum transport by quasi-particles, and the uncertainty relation suggests that the ratio of shear viscosity η to entropy density s in units of ℏ/kB is bounded by a constant. Here, ℏ is Planck's constant and kB is Boltzmann's constant. A specific bound has been proposed on the basis of string theory where, for a large class of theories, one can show that η/s ⩾ ℏ/(4πkB). We will refer to a fluid that saturates the string theory bound as a perfect fluid. In this review we summarize theoretical and experimental information on the properties of the three main classes of quantum fluids that are known to have values of η/s that are smaller than ℏ/kB. These fluids are strongly coupled Bose fluids, in particular liquid helium, strongly correlated ultracold Fermi gases and the quark gluon plasma. We discuss the main theoretical approaches to transport properties of these fluids: kinetic theory, numerical simulations based on linear response theory and holographic dualities. We also summarize the experimental situation, in particular with regard to the observation of hydrodynamic behavior in ultracold Fermi gases and the quark gluon plasma.
Subfields: Atomic and Molecular Physics, and Optics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/343e9001e4e06bb3e2731343ca2ca451c27616f6
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Citations in the corpus
- Gravity and hydrodynamics: lectures on the fluid-gravity correspondence (2009, background): “ject. The fluid-gravity correspondence [4] itself was motivated in part by these 3For a recent account of the nearly ideal fluids in encountered nature, such as the QCP and cold atoms at unitarity, see [24]. 5 studies and the attempts to construct the holographic dual of the so called Bjorken flow [45,”
- Stickiness of sound: An absolute lower limit on viscosity and the breakdown of second-order relativistic hydrodynamics (2011, background): “[18] T.”
- A Holographic View on Physics out of Equilibrium (2010, methodology): “Fits to data from the STAR detector at RHIC suggests that the QGP behaves close to the deconfinement transition in QCD as a nearly-ideal fluid with very low viscosity (see [73] for a discussion of near perfect fluidity in physical systems).”
- Strongly correlated quantum fluids: ultracold quantum gases, quantum chromodynamic plasmas and holographic duality (2012, background): “e quark-gluon plasma (QGP). This is a vast subject and we will not attempt to provide a comprehensive review here. Recent reviews of various issues related to quark matter and the QGP can be found in [180, 181, 182, 183, 20, 184] and the results from the experimental program at the Relativistic Heav”
- Gauge/String Duality, Hot QCD and Heavy Ion Collisions (2011, background): “~ Z(1) = z 2 ~ Z [2] (1) + z 3 ~ Z [3] (1) + .”
- Holographic Duality with a View Toward Many-Body Physics (2009, background): “The substances which come the closest [67] are cold atoms at unitarity ( s ∼ 1 2 [68]) and the fireball at RHIC ( s ∼ 0.”
- Lectures on hydrodynamic fluctuations in relativistic theories (2012, background): “The two main competitors for the most nearly-perfect fluid are the ultracold Fermi gases and the quark–gluon plasma, see [10] for a review.”