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@ARTICLE{He:890689,
      author       = {He, Rongzheng and Li, Ning and Lu, Bing-Nan and Lee, Dean},
      title        = {{S}uperfluid condensate fraction and pairing wave function
                      of the unitary {F}ermi gas},
      journal      = {Physical review / A},
      volume       = {101},
      number       = {6},
      issn         = {2469-9926},
      address      = {Woodbury, NY},
      publisher    = {Inst.},
      reportid     = {FZJ-2021-01131},
      pages        = {063615},
      year         = {2020},
      abstract     = {The unitary Fermi gas is a many-body system of
                      two-component fermions with zero-range interactions tuned to
                      infinite scattering length. Despite much activity and
                      interest in unitary Fermi gases and its universal
                      properties, there have been great difficulties in performing
                      accurate calculations of the superfluid condensate fraction
                      and pairing wave function. In this work we present
                      auxiliary-field lattice Monte Carlo simulations using a
                      novel lattice interaction which accelerates the approach to
                      the continuum limit, thereby allowing for robust
                      calculations of these difficult observables. As a benchmark
                      test we compute the ground state energy of 33 spin-up and 33
                      spin-down particles. As a fraction of the free Fermi gas
                      energy $E_{FG}$, we find $E_0/E_{FG}=0.369(2),0.372(2)$,
                      using two different definitions of the finite-system energy
                      ratio, in agreement with the latest theoretical and
                      experimental results. We then determine the condensate
                      fraction by measuring off-diagonal long-range order in the
                      two-body density matrix. We find that the fraction of
                      condensed pairs is $α=0.43(2)$. We also extract the pairing
                      wave function and find the pair correlation length to be
                      $ζ_pk_F=1.8(3)ℏ$, where $k_F$ is the Fermi momentum.
                      Provided that the simulations can be performed without
                      severe sign oscillations, the methods we present here can be
                      applied to superfluid neutron matter as well as more exotic
                      P-wave and D-wave superfluids.},
      ddc          = {530},
      pnm          = {Nuclear Lattice Simulations $(jara0015_20200501)$},
      pid          = {$G:(DE-Juel1)jara0015_20200501$},
      typ          = {PUB:(DE-HGF)16},
      doi          = {10.1103/PhysRevA.101.063615},
      url          = {https://juser.fz-juelich.de/record/890689},
}