Discrete breathers and negative-temperature states

Stefano Iubini, Roberto Franzosi, Roberto Livi, Gian-Luca Oppo, Antonio Politi

Research output: Contribution to journalLetter

24 Citations (Scopus)

Abstract

We explore the statistical behaviour of the discrete nonlinear Schrödinger equation as a test bed for the observation of negative-temperature (i.e. above infinite temperature) states in Bose–Einstein condensates in optical lattices and arrays of optical waveguides. By monitoring the microcanonical temperature, we show that there exists a parameter region where the system evolves towards a state characterized by a finite density of discrete breathers and a negative temperature. Such a state persists over very long (astronomical) times since the convergence to equilibrium becomes increasingly slower as a consequence of a coarsening process. We also discuss two possible mechanisms for the generation of negative-temperature states in experimental setups, namely, the introduction of boundary dissipations and the free expansion of wavepackets initially in equilibrium at a positive temperature.
LanguageEnglish
Article number023032
Number of pages13
JournalNew Journal of Physics
Volume15
Issue number2
DOIs
Publication statusPublished - 19 Feb 2013

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temperature
test stands
Bose-Einstein condensates
optical waveguides
nonlinear equations
dissipation
expansion

Keywords

  • discrete breathers
  • optical waveguides
  • BEC
  • negative temperatures

Cite this

Iubini, Stefano ; Franzosi, Roberto ; Livi, Roberto ; Oppo, Gian-Luca ; Politi, Antonio. / Discrete breathers and negative-temperature states. In: New Journal of Physics. 2013 ; Vol. 15, No. 2.
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Discrete breathers and negative-temperature states. / Iubini, Stefano; Franzosi, Roberto; Livi, Roberto; Oppo, Gian-Luca; Politi, Antonio.

In: New Journal of Physics, Vol. 15, No. 2, 023032, 19.02.2013.

Research output: Contribution to journalLetter

TY - JOUR

T1 - Discrete breathers and negative-temperature states

AU - Iubini, Stefano

AU - Franzosi, Roberto

AU - Livi, Roberto

AU - Oppo, Gian-Luca

AU - Politi, Antonio

PY - 2013/2/19

Y1 - 2013/2/19

N2 - We explore the statistical behaviour of the discrete nonlinear Schrödinger equation as a test bed for the observation of negative-temperature (i.e. above infinite temperature) states in Bose–Einstein condensates in optical lattices and arrays of optical waveguides. By monitoring the microcanonical temperature, we show that there exists a parameter region where the system evolves towards a state characterized by a finite density of discrete breathers and a negative temperature. Such a state persists over very long (astronomical) times since the convergence to equilibrium becomes increasingly slower as a consequence of a coarsening process. We also discuss two possible mechanisms for the generation of negative-temperature states in experimental setups, namely, the introduction of boundary dissipations and the free expansion of wavepackets initially in equilibrium at a positive temperature.

AB - We explore the statistical behaviour of the discrete nonlinear Schrödinger equation as a test bed for the observation of negative-temperature (i.e. above infinite temperature) states in Bose–Einstein condensates in optical lattices and arrays of optical waveguides. By monitoring the microcanonical temperature, we show that there exists a parameter region where the system evolves towards a state characterized by a finite density of discrete breathers and a negative temperature. Such a state persists over very long (astronomical) times since the convergence to equilibrium becomes increasingly slower as a consequence of a coarsening process. We also discuss two possible mechanisms for the generation of negative-temperature states in experimental setups, namely, the introduction of boundary dissipations and the free expansion of wavepackets initially in equilibrium at a positive temperature.

KW - discrete breathers

KW - optical waveguides

KW - BEC

KW - negative temperatures

U2 - 10.1088/1367-2630/15/2/023032

DO - 10.1088/1367-2630/15/2/023032

M3 - Letter

VL - 15

JO - New Journal of Physics

T2 - New Journal of Physics

JF - New Journal of Physics

SN - 1367-2630

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