• DOI:10.1126/science.1224953
• Corpus ID: 11544049

Relaxation and Prethermalization in an Isolated Quantum System

@article{Gring2012RelaxationAP,
  title={Relaxation and Prethermalization in an Isolated Quantum System},
  author={Michael P. Gring and Maximilian Kuhnert and Tim Langen and Takuya Kitagawa and Bernhard Rauer and Matthias Schreitl and Igor E. Mazets and Donald A. Smith and Eugene A. Demler and J{\"o}rg Schmiedmayer},
  journal={Science},
  year={2012},
  volume={337},
  pages={1318 - 1322}
}

• M. Gring, M. Kuhnert, +7 authors J. Schmiedmayer
• Published 30 November 2011
• Physics
• Science

Prethermalization When a physical system is subjected to a rapid change of conditions (for example, a gas of atoms is allowed to occupy a volume twice the size of the original container), it quickly achieves a new temperature (thermalizes) through collisions. However, in some quantum systems many conserved variables inhibit thermalization; understanding the phases the systems go through in the slowing process is of great interest to cosmologists and physicists. Gring et al. (p. 1318, published online 31 August) separate an ultracold one-dimensional gas of bosonic atoms into two nearly identical halves, and follow how local differences in phase between the halves evolve in time by examining their interference. Initially, the local phases are almost identical, but a rapid decoherence ensues, followed by a very slow further decay. The authors analyze the relative state reached after the initial fast decay and find that it can be described by an equilibrium function with an effective temperature several times less than the initial temperature. Because this cannot be the final state of the system, the authors term the initial process prethermalization. Two halves of a split ultracold gas of rubidium atoms retain memory of the initial state for an extended time. Understanding relaxation processes is an important unsolved problem in many areas of physics. A key challenge is the scarcity of experimental tools for the characterization of complex transient states. We used measurements of full quantum mechanical probability distributions of matter-wave interference to study the relaxation dynamics of a coherently split one-dimensional Bose gas and obtained comprehensive information about the dynamical states of the system. After an initial rapid evolution, the full distributions reveal the approach toward a thermal-like steady state characterized by an effective temperature that is independent from the initial equilibrium temperature of the system before the splitting process. We conjecture that this state can be described through a generalized Gibbs ensemble and associate it with prethermalization.