Investigation of the Bosonic Spectrum of Two-Dimensional Optical Graphene-Type Lattices. Superfluid Phase
DOI:
https://doi.org/10.15407/ujpe59.10.0993Keywords:
optical lattice, honeycomb lattice, phase transition, spectral density, hard-core bosons, Dirac pointsAbstract
The energy spectrum of a system of Bose atoms in the superfluid phase in an optical lattice of the graphene type has been studied. The dispersion laws for the energy bands and the single particle spectral densities are calculated in the random phase approximation and in the framework of the hard-core boson formalism, and their changes at the transition from the normal phase to the superfluid one are described. As a result of this transformation, the number of subbands doubles. In the case of the subband energetic equivalence, the Dirac points in the spectrum survive, and their number becomes twice as much. When the subbands are energetically nonequivalent, the Dirac points are absent. The shape of spectral densities is shown to be sensitive to the changes in the temperature and the chemical potential position.
References
I.V. Stasyuk, I.R. Dulepa, and O.V. Velychko, Ukr. J. Phys. 59, 888 (2014).
https://doi.org/10.15407/ujpe59.09.0888
M. Greiner, O. Mandel, T. Esslinger, T.W. H¨ansch, and I. Bloch, Nature 415, 39 (2002).
https://doi.org/10.1038/415039a
M. Greiner, O. Mandel, T.W. H¨ansch, and I. Bloch, Nature 419, 51 (2002).
https://doi.org/10.1038/nature00968
P. Soltau-Panahi, J. Struck, A. Bick, W. Plenkers, G. Meineke, C. Becker, P. Windpassinger, K. Sengstock, P. Hauke, and M. Lewenstein, Nature Physics 7, 434 (2011).
D.-S. L¨uhmann, Phys. Rev. A 87, 043619 (2013).
https://doi.org/10.1103/PhysRevA.87.043619
Q.-Q. Lu and J.-M. Hou, Commun. Theor. Phys. 53, 861 (2010).
https://doi.org/10.1088/0253-6102/53/5/14
P. Soltau-Panahi, D.-S. L¨uhmann, J. Struck, P. Windpassinger, and K. Sengstock, Nature Physics 8, 71 (2012).
E. Albus, X. Fernandez-Gonzalvo, J. Mur-Petit, J.J. Garcia-Ripoli, and J.K. Pachos, Ann. Phys. 328, 64 (2013).
https://doi.org/10.1016/j.aop.2012.10.005
M.P.A. Fisher, P.B. Weichman, G. Grinstein, and D.S. Fisher, Phys. Rev. B 40, 546 (1989).
https://doi.org/10.1103/PhysRevB.40.546
D. Jaksch, C. Bruder, J.I. Cirac, C.W. Gardiner, and P. Zoller, Phys. Rev. Lett. 81, 3108 (1998).
https://doi.org/10.1103/PhysRevLett.81.3108
Z. Chen and B. Wu, Phys. Rev. Lett. 107, 065301 (2011).
https://doi.org/10.1103/PhysRevLett.107.065301
S. Koghee, L.-K. Lim, M.O. Goerbig, and C. Morais-Smith, Phys. Rev. A 85, 023637 (2012).
https://doi.org/10.1103/PhysRevA.85.023637
R.T. Whitlock and P.R. Zilsel, Phys. Rev. 131, 2409 (1963).
https://doi.org/10.1103/PhysRev.131.2409
I.V. Stasyuk and O. Vorobyov, Condens. Matter Phys. 16, 23005 (2013).
https://doi.org/10.5488/CMP.16.23005
A.H. Castro Neto, F. Guinea, N.M.R. Peres, K.S. Novoselov, and A.K. Geim, Rev. Mod. Phys. 81, 109 (2009).
https://doi.org/10.1103/RevModPhys.81.109
N.N. Bogolyubov, Izv. Akad. Nauk SSSR Ser. Fiz. 11, 77 (1947).
H.B. Rosenstock, J. Chem. Phys. 21, 2064 (1953).
https://doi.org/10.1063/1.1698743
J.P. Hobson and W.A. Nierenberg, Phys. Rev. 89, 662 (1953).
Downloads
Published
How to Cite
Issue
Section
License
Copyright Agreement
License to Publish the Paper
Kyiv, Ukraine
The corresponding author and the co-authors (hereon referred to as the Author(s)) of the paper being submitted to the Ukrainian Journal of Physics (hereon referred to as the Paper) from one side and the Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, represented by its Director (hereon referred to as the Publisher) from the other side have come to the following Agreement:
1. Subject of the Agreement.
The Author(s) grant(s) the Publisher the free non-exclusive right to use the Paper (of scientific, technical, or any other content) according to the terms and conditions defined by this Agreement.
2. The ways of using the Paper.
2.1. The Author(s) grant(s) the Publisher the right to use the Paper as follows.
2.1.1. To publish the Paper in the Ukrainian Journal of Physics (hereon referred to as the Journal) in original language and translated into English (the copy of the Paper approved by the Author(s) and the Publisher and accepted for publication is a constitutive part of this License Agreement).
2.1.2. To edit, adapt, and correct the Paper by approval of the Author(s).
2.1.3. To translate the Paper in the case when the Paper is written in a language different from that adopted in the Journal.
2.2. If the Author(s) has(ve) an intent to use the Paper in any other way, e.g., to publish the translated version of the Paper (except for the case defined by Section 2.1.3 of this Agreement), to post the full Paper or any its part on the web, to publish the Paper in any other editions, to include the Paper or any its part in other collections, anthologies, encyclopaedias, etc., the Author(s) should get a written permission from the Publisher.
3. License territory.
The Author(s) grant(s) the Publisher the right to use the Paper as regulated by sections 2.1.1–2.1.3 of this Agreement on the territory of Ukraine and to distribute the Paper as indispensable part of the Journal on the territory of Ukraine and other countries by means of subscription, sales, and free transfer to a third party.
4. Duration.
4.1. This Agreement is valid starting from the date of signature and acts for the entire period of the existence of the Journal.
5. Loyalty.
5.1. The Author(s) warrant(s) the Publisher that:
– he/she is the true author (co-author) of the Paper;
– copyright on the Paper was not transferred to any other party;
– the Paper has never been published before and will not be published in any other media before it is published by the Publisher (see also section 2.2);
– the Author(s) do(es) not violate any intellectual property right of other parties. If the Paper includes some materials of other parties, except for citations whose length is regulated by the scientific, informational, or critical character of the Paper, the use of such materials is in compliance with the regulations of the international law and the law of Ukraine.
6. Requisites and signatures of the Parties.
Publisher: Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine.
Address: Ukraine, Kyiv, Metrolohichna Str. 14-b.
Author: Electronic signature on behalf and with endorsement of all co-authors.
.png){kind=small}
