TY  - JOUR
AU  - Maluckov, Aleksandra
AU  - Gligorić, Goran
AU  - Hadžievski, Ljupčo
AU  - Malomed, Boris A.
AU  - Pfau, Tilman
PY  - 2013
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5319
AB  - We study normal modes propagating on top of the stable uniform background in arrays of dipolar Bose-Einstein condensate (BEC) droplets trapped in a deep optical lattice. Both the on-site mean-field dynamics of the droplets and their displacement due to the repulsive dipole-dipole interactions (DDIs) are taken into account. Dispersion relations for two modes, viz., high-and low-frequency counterparts of optical and acoustic phonon modes in condensed matter, are derived analytically and verified by direct simulations, for both cases of the repulsive and attractive contact interactions. The (counterpart of the) optical-phonon branch does not exist without the DDIs. These results are relevant in the connection to emerging experimental techniques enabling real-time imaging of the condensate dynamics and direct experimental measurement of phonon dispersion relations in BECs. DOI: 10.1103/PhysRevA.87.023623
T2  - Physical Review A
T1  - High- and low-frequency phonon modes in dipolar quantum gases trapped in deep lattices
VL  - 87
IS  - 2
DO  - 10.1103/PhysRevA.87.023623
ER  - 

@article{
author = "Maluckov, Aleksandra and Gligorić, Goran and Hadžievski, Ljupčo and Malomed, Boris A. and Pfau, Tilman",
year = "2013",
abstract = "We study normal modes propagating on top of the stable uniform background in arrays of dipolar Bose-Einstein condensate (BEC) droplets trapped in a deep optical lattice. Both the on-site mean-field dynamics of the droplets and their displacement due to the repulsive dipole-dipole interactions (DDIs) are taken into account. Dispersion relations for two modes, viz., high-and low-frequency counterparts of optical and acoustic phonon modes in condensed matter, are derived analytically and verified by direct simulations, for both cases of the repulsive and attractive contact interactions. The (counterpart of the) optical-phonon branch does not exist without the DDIs. These results are relevant in the connection to emerging experimental techniques enabling real-time imaging of the condensate dynamics and direct experimental measurement of phonon dispersion relations in BECs. DOI: 10.1103/PhysRevA.87.023623",
journal = "Physical Review A",
title = "High- and low-frequency phonon modes in dipolar quantum gases trapped in deep lattices",
volume = "87",
number = "2",
doi = "10.1103/PhysRevA.87.023623"
}

Maluckov, A., Gligorić, G., Hadžievski, L., Malomed, B. A.,& Pfau, T.. (2013). High- and low-frequency phonon modes in dipolar quantum gases trapped in deep lattices. in Physical Review A, 87(2).
https://doi.org/10.1103/PhysRevA.87.023623

Maluckov A, Gligorić G, Hadžievski L, Malomed BA, Pfau T. High- and low-frequency phonon modes in dipolar quantum gases trapped in deep lattices. in Physical Review A. 2013;87(2).
doi:10.1103/PhysRevA.87.023623 .

Maluckov, Aleksandra, Gligorić, Goran, Hadžievski, Ljupčo, Malomed, Boris A., Pfau, Tilman, "High- and low-frequency phonon modes in dipolar quantum gases trapped in deep lattices" in Physical Review A, 87, no. 2 (2013),
https://doi.org/10.1103/PhysRevA.87.023623 . .

TY  - JOUR
AU  - Maluckov, Aleksandra
AU  - Gligorić, Goran
AU  - Hadžievski, Ljupčo
AU  - Malomed, Boris A.
AU  - Pfau, Tilman
PY  - 2012
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/4357
AB  - Density-wave patterns in discrete media with local interactions are known to be unstable. We demonstrate that stable double-and triple-period patterns (DPPs and TPPs), with respect to the period of the underlying lattice, exist in media with nonlocal nonlinearity. This is shown in detail for dipolar Bose-Einstein condensates, loaded into a deep one-dimensional optical lattice. The DPP and TPP emerge via phase transitions of the second and first kind, respectively. The emerging patterns may be stable if the dipole-dipole interactions are repulsive and sufficiently strong, in comparison with the local repulsive nonlinearity. Within the set of the considered states, the TPPs realize a minimum of the free energy. Avast stability region for the TPPs is found in the parameter space, while the DPP stability region is relatively narrow. The same mechanism may create stable density-wave patterns in other physical media featuring nonlocal interactions.
T2  - Physical Review Letters
T1  - Stable Periodic Density Waves in Dipolar Bose-Einstein Condensates Trapped in Optical Lattices
VL  - 108
IS  - 14
DO  - 10.1103/PhysRevLett.108.140402
ER  - 

@article{
author = "Maluckov, Aleksandra and Gligorić, Goran and Hadžievski, Ljupčo and Malomed, Boris A. and Pfau, Tilman",
year = "2012",
abstract = "Density-wave patterns in discrete media with local interactions are known to be unstable. We demonstrate that stable double-and triple-period patterns (DPPs and TPPs), with respect to the period of the underlying lattice, exist in media with nonlocal nonlinearity. This is shown in detail for dipolar Bose-Einstein condensates, loaded into a deep one-dimensional optical lattice. The DPP and TPP emerge via phase transitions of the second and first kind, respectively. The emerging patterns may be stable if the dipole-dipole interactions are repulsive and sufficiently strong, in comparison with the local repulsive nonlinearity. Within the set of the considered states, the TPPs realize a minimum of the free energy. Avast stability region for the TPPs is found in the parameter space, while the DPP stability region is relatively narrow. The same mechanism may create stable density-wave patterns in other physical media featuring nonlocal interactions.",
journal = "Physical Review Letters",
title = "Stable Periodic Density Waves in Dipolar Bose-Einstein Condensates Trapped in Optical Lattices",
volume = "108",
number = "14",
doi = "10.1103/PhysRevLett.108.140402"
}

Maluckov, A., Gligorić, G., Hadžievski, L., Malomed, B. A.,& Pfau, T.. (2012). Stable Periodic Density Waves in Dipolar Bose-Einstein Condensates Trapped in Optical Lattices. in Physical Review Letters, 108(14).
https://doi.org/10.1103/PhysRevLett.108.140402

Maluckov A, Gligorić G, Hadžievski L, Malomed BA, Pfau T. Stable Periodic Density Waves in Dipolar Bose-Einstein Condensates Trapped in Optical Lattices. in Physical Review Letters. 2012;108(14).
doi:10.1103/PhysRevLett.108.140402 .

Maluckov, Aleksandra, Gligorić, Goran, Hadžievski, Ljupčo, Malomed, Boris A., Pfau, Tilman, "Stable Periodic Density Waves in Dipolar Bose-Einstein Condensates Trapped in Optical Lattices" in Physical Review Letters, 108, no. 14 (2012),
https://doi.org/10.1103/PhysRevLett.108.140402 . .