### Abstract

We extend our earlier study of the ground state of a bosonic quasiparticle Hamiltonian by investigating the effect of a constant external velocity field. Below a critical velocity the ground state is a quasiparticle vacuum, corresponding to a pure superfluid phase at zero temperature. Beyond the critical velocity energy minimization leads to a macroscopic condensation of quasiparticles at a nonzero wave vector k_{v} parallel to the velocity v. Simultaneously, physical particles also undergo a condensation at k _{v} and, to a smaller extent, at -k_{v}. Together with the Bose-Einstein condensation at k=0, the three coexisting condensates give rise to density modulations of wave vectors k_{v} and 2k_{v}. For larger |v| our model predicts a bifurcation of k_{v} with corresponding two pure condensates and no density modulation.

Original language | English |
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Article number | 043640 |

Journal | Physical Review A |

Volume | 88 |

Issue number | 4 |

DOIs | |

Publication status | Published - okt. 29 2013 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

**Condensation of quasiparticles and density modulation beyond the superfluid critical velocity.** / Süto, András; Szépfalusy, P.

Research output: Article

*Physical Review A*, vol. 88, no. 4, 043640. https://doi.org/10.1103/PhysRevA.88.043640

}

TY - JOUR

T1 - Condensation of quasiparticles and density modulation beyond the superfluid critical velocity

AU - Süto, András

AU - Szépfalusy, P.

PY - 2013/10/29

Y1 - 2013/10/29

N2 - We extend our earlier study of the ground state of a bosonic quasiparticle Hamiltonian by investigating the effect of a constant external velocity field. Below a critical velocity the ground state is a quasiparticle vacuum, corresponding to a pure superfluid phase at zero temperature. Beyond the critical velocity energy minimization leads to a macroscopic condensation of quasiparticles at a nonzero wave vector kv parallel to the velocity v. Simultaneously, physical particles also undergo a condensation at k v and, to a smaller extent, at -kv. Together with the Bose-Einstein condensation at k=0, the three coexisting condensates give rise to density modulations of wave vectors kv and 2kv. For larger |v| our model predicts a bifurcation of kv with corresponding two pure condensates and no density modulation.

AB - We extend our earlier study of the ground state of a bosonic quasiparticle Hamiltonian by investigating the effect of a constant external velocity field. Below a critical velocity the ground state is a quasiparticle vacuum, corresponding to a pure superfluid phase at zero temperature. Beyond the critical velocity energy minimization leads to a macroscopic condensation of quasiparticles at a nonzero wave vector kv parallel to the velocity v. Simultaneously, physical particles also undergo a condensation at k v and, to a smaller extent, at -kv. Together with the Bose-Einstein condensation at k=0, the three coexisting condensates give rise to density modulations of wave vectors kv and 2kv. For larger |v| our model predicts a bifurcation of kv with corresponding two pure condensates and no density modulation.

UR - http://www.scopus.com/inward/record.url?scp=84887086533&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84887086533&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.88.043640

DO - 10.1103/PhysRevA.88.043640

M3 - Article

AN - SCOPUS:84887086533

VL - 88

JO - Physical Review A

JF - Physical Review A

SN - 2469-9926

IS - 4

M1 - 043640

ER -