arXiv:1310.6350 · Physical Review A

Frustrated phase separation in the momentum distribution of field-driven light-heavy Fermi-Fermi mixtures of ultracold atoms

Herbert F. Fotso, J. Vicente, James K. Freericks

Published Nov 25, 2014• 1 citation

Abstract

Time-of-flight images are a common tool in ultracold atomic experiments, employed to determine the quasimomentum distribution of the interacting particles. If one introduces a constant artificial electric field, then the quasimomentum distribution evolves in time as Bloch oscillations are generated in the system and then are damped, showing a complex series of patterns. In different-mass Fermi-Fermi mixtures, these patterns are formed from a frustrated phase separation in momentum space that is driven by Mott physics for large electric fields which stabilize them for long times.

DOI: 10.1103/physreva.90.053630

Related papers

Pattern formation in time-of-flight images of heavy-light mixtures of atoms undergoing Bloch oscillations

James K. Freericks

Bulletin of the American Physical SocietyFeb 28, 20120 citations

Pattern Formation in Mixtures of Ultracold Atoms in Optical Lattices

Maciej M. Maśka, R. Lemański, James K. Freericks +1 more

Regular pattern formation is ubiquitous in nature; it occurs in biological, physical, and materials science systems. Here we propose a set of experiments with ultracold atoms that show how to examine different types of pattern formation. In particular, we show how one can see the analog of labyrinthine patterns (so-called quantum emulsions) in mixtures of light and heavy atoms (that tend to phase separate) by tuning the trap potential and we show how complex geometrically ordered patterns emerge (when the mixtures do not phase separate), which could be employed for low-temperature thermometry. The complex physical mechanisms for the pattern formation at zero temperature are understood within a theoretical analysis called the local density approximation.

arXiv:0802.3894Physical Review LettersAug 7, 200832 citations

Ultracold Bose gases in time-dependent one-dimensional superlattices: Response and quasimomentum structure

Markus Hild, Felix Schmitt, Ilona Türschmann +1 more

The response of ultracold atomic Bose gases in time-dependent optical lattices is discussed based on direct simulations of the time-evolution of the many-body state in the framework of the Bose-Hubbard model. We focus on small-amplitude modulations of the lattice potential as implemented in several recent experiments and study different observables in the region of the first resonance in the Mott-insulator phase. In addition to the energy transfer we investigate the quasimomentum structure of the system which is accessible via the matter-wave interference pattern after a prompt release. We identify characteristic correlations between the excitation frequency and the quasimomentum distribution and study their structure in the presence of a superlattice potential.

arXiv:0706.4260Physical Review ANov 16, 20075 citations

Spin-orbit-driven transitions between Mott insulators and finite-momentum superfluids of bosons in optical lattices

Mi Yan, Yinyin Qian, Hoi-Yin Hui +3 more

Synthetic spin-orbit coupling in ultracold atomic gases can be taken to extremes rarely found in solids. We study a two-dimensional Hubbard model of bosons in an optical lattice in the presence of spin-orbit coupling strong enough to drive direct transitions from Mott insulators to superfluids. Here we find phase-modulated superfluids with finite momentum that are generated entirely by spin-orbit coupling. We investigate the rich phase patterns of the superfluids, which may be directly probed using time-of-flight imaging of the spin-dependent momentum distribution.

Physical Review ANov 13, 201712 citations

Bloch Oscillations of Atoms in an Optical Potential

Maxime Dahan, E. Peik, Jakob Reichel +2 more

Ultracold cesium atoms are prepared in the ground energy band of the potential induced by an optical standing wave. We observe Bloch oscillations of the atoms driven by a constant inertial force. We measure the momentum distribution of Bloch states and effective masses different from the mass of the free atom.

Physical Review LettersJun 10, 1996958 citations

Emergent phenomena in quantum mixtures: from ultra-cold gases to light-matter systems

Matteo Caldara

Quantum mixtures of ultra-cold atoms are exceptional platforms which allow to investigate a huge variety of phenomena owing to the exquisite control of interactions between atoms. We present here a theoretical investigation of some distinctive phenomena emerging in these systems which highlight their quantum nature. Balanced mixtures at sufficiently low temperatures are superfluid and, when set into rotation, they display topological excitations in the form of quantum vortices. In many physical systems, especially in quantum mixtures, the scenario is richer as the vortex core is filled, either deliberately or accidentally, by particles and then stable massive vortices appear. The finite inertial mass has an unmistakable dynamical signature in the trajectory of vortices in two-dimensional superfluids. On the one hand, in bosonic mixtures massive vortices may appear in the immiscible regime where one (majority) component features topological excitations and the other (minority) component localizes at the vortex cores. On the other hand, in Fermi superfluids vortices are intrinsically massive, due to the presence of normal component at the vortex core. Together with dissipative effects, the core mass is expected to affect the collective properties of many-vortex systems, such as providing a stabilization mechanism for usual shear-flow instabilities that have been currently investigated in experiments. In the strongly imbalanced regime, quantum mixtures offer a unique viewpoint on the well-known impurity problem. In particular, the strongly-interacting system made of an impurity atom in a Fermi sea can be described in terms of a Fermi polaron, the prototypical realization of Landau's fundamental concept of quasiparticle. We study the behaviour of the moving Fermi polaron, finding a breakdown of the effective mass description at finite momentum which finds a solid confirmation in a cold-atom experiment. A novel type of quantum liquid may also appear in ultra-cold bosonic mixtures from a competition between interactions. When the mean-field attraction is balanced by a repulsion induced by quantum fluctuations, the system stabilizes into a self-bound configuration, known as quantum droplet. While this physics has been explored in the context of quantum gases, we predict here the existence of a similar droplet phase in a solid-state system with light-matter interactions. We consider a spin mixture of exciton-polaritons, hybrid light-matter quasiparticles formed from the strong coupling between excitons (bound electron-hole pairs) and photons in a semiconductor microcavity. This exotic phase could open an alternative avenue to achieve the long-sought quantum polaritonic regime.

Sep 12, 20250 citations