Quantum phase transitions and the degree of nonidentity in the system with two different species of vector bosons

Abstract

We present new results for the system with two species of vector bosons in an optical lattice. In addition to the standard parameters characterizing such a system, we are dealing here with the 'degree of atomic nonidentity', manifesting itself in the difference of tunneling amplitudes and on-site Coulomb interactions. We obtain a cascade of quantum phase transitions occurring with the increase in the degree of atomic nonidentity. While in the system of nearly identical vector bosons only one phase transition between two phases occurs with the evolution of the interparticle interaction, atom nonidentity increases the number of possible phases to six and the resulting phase diagrams are so nontrivial that we can speculate about their evolution from the images similar to the 'JMiró-like paintings' to 'KMalewicz-like' ones.

The mixing-demixing phase diagram of ultracold heteronuclear mixtures in a ring trimer

“…In this prospective, 23 Na + 39 K constitutes an ideal mixture. The spin mixture | f = 1, m f = −1 Na + | f = 1, m f = −1 K , where f is the atomic total angular momentum and m f its projection on the quantization axis, has been recently doubly Bose-condensed and presents a favorable window of magnetic field (from 90 to 150 G) where the combination of two intra-and two inter-species resonances allow for a smooth tuning of the scattering lengths 43 (see left panel of Fig.…”

“…Fragmentation of bosonic mixtures in arrays of potential wells constitutes an important factor in determining their mixing properties and plays a crucial role, together with the repulsion between the mixture's components, in triggering spatial phase separation. A large amount of recent theoretical studies have revealed a colorful phenomenology ranging from phase separation mechanism 15,16 , demixing of dipolar mixtures 17 , and quantum emulsions 18,19 to the critical properties of quasiparticles spectrum across the transition 20 , thermal suppression 21 and the role of entanglement 22 in phase separation, and cascades of quantum phase transitions of vector bosons 23 .…”

“…Left panel: Intra-and inter-species scattering lengths for | f = 1, m f = −123 Na + | f = 1, m f = −1 39 K mixture given in the Bohr radii a 0 . Yellow dashed, red dotted and blue continuous line refer to sodium a Na , potassium a K and sodium-potassium a Na,K scattering lengths.…”

Quantum-Granularity Effect in the Formation of Supermixed Solitons in Ring Lattices

“…The behaviour of the latter is ruled by the competition among tunnelling processes (resulting from the spatial fragmentation of the condensates into separated wells), intra-and the inter-species couplings. Such interplay among different contributions in the overall energy balance of the system results, among the rest, in a rich scenario of mixing-demixing quantum phase transitions [5,6,7,8,9], in the emergence of novel quantum phases [10,11,12], in the possibility of entangling [13,14] the two bosonic species, and in that of triggering peculiar dynamical regimes [15,16].…”

Pathway toward the formation of supermixed states in ultracold boson mixtures loaded in ring lattices

“…Conversely, going out of region (13), the uniform solution ceases to be a local (and also the global) minimum of function (3), a circumstance which corresponds to the onset of the transition between phase M and phase PL. Remarkably, in the limit T a /(U a N a ) → 0 and T b /(U b N b ) → 0, inequalities (10), (11), (12) and (13) reduce to α > −1, the condition which was shown to constitute the border between phase M and PL in the thermodynamic limit (see Figure 1). In passing, one can observe that, for L = 2, the mismatch between inequalities (13) and (11) is only apparent, in that the former is referred to a system inherently featuring the ring geometry which is absent in the dimer.…”