Phase Diagram of a Quantum Lattice Gas with Repulsive Interaction.

We study a gas of strongly polarized cold fermions in an optical lattice when the excited $p$ bands are populated. We derive the relevant Hamiltonian and discuss the expected phase diagram for both repulsive and attractive interactions. In the parameter regime covered here, checkerboard antiferromagnetic ordering is found to be possible for repulsive interactions, while for attractive interactions, transitions between different types of paired phases are predicted.We study a gas of strongly polarized cold fermions in an optical lattice when the excited $p$ bands are populated. We derive the relevant Hamiltonian and discuss the expected phase diagram for both repulsive and attractive interactions. In the parameter regime covered here, checkerboard antiferromagnetic ordering is found to be possible for repulsive interactions, while for attractive interactions, transitions between different types of paired phases are predicted.

arXiv:0804.3280Physical Review AAug 5, 20086 citations

Phase diagram and momentum distribution of an interacting Bose gas in a bichromatic lattice

Xiaolong Deng, R. Citro, Anna Minguzzi +1 more

We determine the phase diagram and the momentum distribution for a one-dimensional Bose gas with repulsive short-range interactions in the presence of a two-color lattice potential, with an incommensurate ratio among the respective wavelengths, by using a combined numerical (density matrix renormalization group) and analytical (bosonization) analysis. The system displays a delocalized (superfluid) phase at small values of the intensity of the secondary lattice ${\mathit{V}}_{2}$ and a localized (Bose-glasslike) phase at larger intensity ${\mathit{V}}_{2}$ . We analyze the localization transition as a function of the height ${\mathit{V}}_{2}$ beyond the known limits of free and hard-core bosons. We find that weak repulsive interactions disfavor the localized phase, i.e., they increase the critical value of ${\mathit{V}}_{2}$ at which localization occurs. In the case of integer filling of the primary lattice, the phase diagram at fixed density displays, in addition to a transition from a superfluid to a Bose glass phase, a transition to a Mott-insulating state for not too large ${\mathit{V}}_{2}$ and large repulsion. We also analyze the emergence of a Bose-glass phase by looking at the evolution of the Mott-insulator lobes when increasing ${\mathit{V}}_{2}$ . The Mott lobes shrink and disappear above a critical value of ${\mathit{V}}_{2}$ . Finally, we characterize the superfluid phase by the momentum distribution, and show that it displays a power-law decay at small momenta typical of Luttinger liquids, with an exponent depending on the combined effect of the interactions and of the secondary lattice. In addition, we observe two side peaks that are due to the diffraction of the Bose gas by the second lattice. This latter feature could be observed in current experiments as characteristics of pseudo-random Bose systems.We determine the phase diagram and the momentum distribution for a one-dimensional Bose gas with repulsive short-range interactions in the presence of a two-color lattice potential, with an incommensurate ratio among the respective wavelengths, by using a combined numerical (density matrix renormalization group) and analytical (bosonization) analysis. The system displays a delocalized (superfluid) phase at small values of the intensity of the secondary lattice ${\mathit{V}}_{2}$ and a localized (Bose-glasslike) phase at larger intensity ${\mathit{V}}_{2}$. We analyze the localization transition as a function of the height ${\mathit{V}}_{2}$ beyond the known limits of free and hard-core bosons. We find that weak repulsive interactions disfavor the localized phase, i.e., they increase the critical value of ${\mathit{V}}_{2}$ at which localization occurs. In the case of integer filling of the primary lattice, the phase diagram at fixed density displays, in addition to a transition from a superfluid to a Bose glass phase, a transition to a Mott-insulating state for not too large ${\mathit{V}}_{2}$ and large repulsion. We also analyze the emergence of a Bose-glass phase by looking at the evolution of the Mott-insulator lobes when increasing ${\mathit{V}}_{2}$. The Mott lobes shrink and disappear above a critical value of ${\mathit{V}}_{2}$. Finally, we characterize the superfluid phase by the momentum distribution, and show that it displays a power-law decay at small momenta typical of Luttinger liquids, with an exponent depending on the combined effect of the interactions and of the secondary lattice. In addition, we observe two side peaks that are due to the diffraction of the Bose gas by the second lattice. This latter feature could be observed in current experiments as characteristics of pseudo-random Bose systems.

arXiv:0803.3128Physical Review AJul 21, 200870 citations

Phase Diagram of a Charged Bose Gas (abstract Only)

J. P. Hansen, B. Jancovici, Daniel Schiff

Jan 1, 19740 citations

Quantum phases of dipolar bosons in one-dimensional optical lattices

Rebecca Kraus, Titas Chanda, Jakub Zakrzewski +1 more

We theoretically analyze the phase diagram of a quantum gas of bosons that interact via repulsive dipolar interactions. The bosons are tightly confined by an optical lattice in a quasi-one-dimensional geometry. In the single-band approximation, their dynamics is described by an extended Bose-Hubbard model where the relevant contributions of the dipolar interactions consist of density-density repulsion and correlated tunneling terms. We evaluate the phase diagram for unit density using numerical techniques based on the density-matrix renormalization group algorithm. Our results predict that correlated tunneling can significantly modify the parameter range of the topological insulator phase. At vanishing values of the onsite interactions, moreover, correlated tunneling promotes the onset of a phase with a large number of low-energy metastable configurations.We theoretically analyze the phase diagram of a quantum gas of bosons that interact via repulsive dipolar interactions. The bosons are tightly confined by an optical lattice in a quasi-one-dimensional geometry. In the single-band approximation, their dynamics is described by an extended Bose-Hubbard model where the relevant contributions of the dipolar interactions consist of density-density repulsion and correlated tunneling terms. We evaluate the phase diagram for unit density using numerical techniques based on the density-matrix renormalization group algorithm. Our results predict that correlated tunneling can significantly modify the parameter range of the topological insulator phase. At vanishing values of the onsite interactions, moreover, correlated tunneling promotes the onset of a phase with a large number of low-energy metastable configurations.

arXiv:2112.10386Physical review. B./Physical review. BJul 25, 202212 citations

We study a gas of strongly polarized cold fermions in an optical lattice when the excited

p

bands are populated. We derive the relevant Hamiltonian and discuss the expected phase diagram for both repulsive and attractive interactions. In the parameter regime covered here, checkerboard antiferromagnetic ordering is found to be possible for repulsive interactions, while for attractive interactions, transitions between different types of paired phases are predicted.

{\mathit{V}}_{2}

and a localized (Bose-glasslike) phase at larger intensity

{\mathit{V}}_{2}

. We analyze the localization transition as a function of the height

{\mathit{V}}_{2}

beyond the known limits of free and hard-core bosons. We find that weak repulsive interactions disfavor the localized phase, i.e., they increase the critical value of

{\mathit{V}}_{2}

at which localization occurs. In the case of integer filling of the primary lattice, the phase diagram at fixed density displays, in addition to a transition from a superfluid to a Bose glass phase, a transition to a Mott-insulating state for not too large

{\mathit{V}}_{2}

and large repulsion. We also analyze the emergence of a Bose-glass phase by looking at the evolution of the Mott-insulator lobes when increasing

{\mathit{V}}_{2}

. The Mott lobes shrink and disappear above a critical value of

{\mathit{V}}_{2}

. Finally, we characterize the superfluid phase by the momentum distribution, and show that it displays a power-law decay at small momenta typical of Luttinger liquids, with an exponent depending on the combined effect of the interactions and of the secondary lattice. In addition, we observe two side peaks that are due to the diffraction of the Bose gas by the second lattice. This latter feature could be observed in current experiments as characteristics of pseudo-random Bose systems.