PaperPanorama

Nuclear Theory·nucl-th

Friday·June 3, 2022

2 papers1 primary·1 cross-listed

  1. 01

    Equilibration and locality

    Marek Gazdzicki🇩🇪 · Mark Gorenstein🇺🇦 · Ivan Pidhurskyi🇩🇪 · Oleh Savchuk🇺🇦 · Leonardo Tinti🇩🇪

    Experiments motivated by predictions of quantum mechanics indicate non-trivial correlations between spacelike-separated measurements. The phenomenon is referred to as a violation of strong-locality and, after Einstein, called ghostly action at a distance. An intriguing and previously unasked question is how the evolution of an assembly of particles to equilibrium-state relates to strong-locality. More specifically, whether, with this respect, indistinguishable particles differ from distinguishable ones. To address the question, we introduce a Markov-chain based framework over a finite set of microstates. For the first time, we formulate conditions needed to obey the particle transport- and strong-locality for indistinguishable particles. Models which obey transport-locality and lead to equilibrium-state are considered. We show that it is possible to construct models obeying and violating strong-locality both for indistinguishable particles and for distinguishable ones. However, we find that only for distinguishable particles strongly-local evolution to equilibrium is possible without breaking the microstate-symmetry. This is the strongest symmetry one can impose and leads to the shortest equilibration time. We hope that the results presented here may provide a new perspective on a violation of strong-locality, and the developed framework will help in future studies. Specifically they may help to interpret results on high-energy nuclear collisions indicating a fast equilibration of indistinguishable particles.

    nucl-thhep-phquant-phActa Phys.Polon.B(2022)·1 citation
  2. 02

    Universal van der Waals Force Between Heavy Polarons in Superfluids

    Keisuke Fujii · Masaru Hongo · Tilman Enss

    We investigate the long-range behavior of the induced Casimir interaction between two spinless heavy impurities, or polarons, in superfluid cold atomic gases. With the help of effective field theory (EFT) of a Galilean invariant superfluid, we show that the induced impurity-impurity potential at long distance universally shows a relativistic van der Waals-like attraction () resulting from the exchange of two superfluid phonons. We also clarify finite temperature effects from the same two-phonon exchange process. The temperature introduces the additional length scale with the speed of sound . Leading corrections at finite temperature scale as for distances smaller than the thermal length. For larger distances the potential shows a nonrelativistic van der Waals behavior () instead of the relativistic one. Our EFT formulation applies not only to weakly coupled Bose or Fermi superfluids but also to that composed of strongly-coupled unitary fermions with a weakly coupled impurity. The sound velocity controls the magnitude of the van der Waals potential, which we evaluate for the fermionic superfluid in the BCS-BEC crossover.

    cond-mat.quant-gashep-thnucl-thPRL(2022)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE