Cold Dipolar Gases in Optical Lattices - Frustration and Disorder
Lead Research Organisation:
University of Oxford
Department Name: Oxford Physics
Abstract
When atoms are cooled down to extremely low temperatures they start to show quantum mechanical properties on a macroscopic scale. The phenomenon of Bose-Einstein condensation (BEC) is one of the best known manifestations of this behavior. The recent experimental success in achieving a BEC in optical lattices, where the interactions among the atoms are larger than the energy of their motion, allows for a new possibility to control them. Because of the strong repulsion the atoms prefer to sit on different lattice sites and form a Mott-insulator where every site is occupied precisely by one atom. If these particles interact over long distances as is the case for dipolar chromium atoms, they can rearrange on the lattice to form very interesting checkerboard structures with the number of atoms changing from one site to another modulated by the period of the lattice. In addition they can form a supersolid which is a crystal with superfluid properties. If we create an optical lattice formed from periodically repeating triangles, the interaction between the particles on neighboring sites will give rise to frustration, the phenomenon which is extensively studied in applications to quantum magnets and superconductivity. It arises when there are many possible configurations of the particles on a lattice which have the same energy. Because of the frustration the atoms on the triangular lattice will show many interesting phases with novel properties. To study dipolar atoms on a lattice is not only of fundamental interest, chromium is a basic material in lithography processes and better understanding of its properties will provide a route towards smaller microchips and faster computers. Furthermore dipolar atoms are promising candidates in the development of robust quantum computers.
People |
ORCID iD |
Dmitry Kovrizhin (Principal Investigator) |
Publications
Kovrizhin Dmitry L.
(2007)
Excitation Spectra of Correlated Lattice Bosons in a Confining Trap
in arXiv e-prints
Matveenko S
(2009)
Vortex structures in rotating Bose-Einstein condensates
in Physical Review A
Kovrizhin D
(2009)
Exactly solved model for an electronic Mach-Zehnder interferometer
in Physical Review B
Kovrizhin D
(2006)
Bose-Einstein condensation of magnons in Cs 2 CuCl 4 : A dilute gas limit near the saturation magnetic field
in Physical Review B
Kovrizhin D
(2010)
Density matrix renormalization group for bosonic quantum Hall effect
in Physical Review B
Kovrizhin D
(2010)
Multiparticle interference in electronic Mach-Zehnder interferometers
in Physical Review B
Kovrizhin D
(2010)
Density matrix renormalization group for bosonic quantum Hall effect
in Physical Review B
Radu T
(2007)
Radu et al. Reply:
in Physical Review Letters
Kovrizhin D
(2009)
Multiparticle interference in electronic Mach-Zehnder interferometers
Kovrizhin D
(2009)
Density matrix renormalization group for bosonic quantum Hall effect
Description | 1. One of the main outcomes of my work on this grant was the theory of electronic Mach-Zehnder interferometers (MZIs), which I have developed together with my collaborator J.T. Chalker (Theoretical Physics, Oxford). In these, recently created mesoscopic systems one can manipulate electron wave-packets, and study electron coherence. Experiments with electronic MZIs showed puzzling behaviour in the non-equilibrium regime (under large applied bias voltage, or in other words when a large number of electrons entered interferometer). In our work we developed the theory which explained experimental puzzles. 2. We developed new theoretical methods of non-equilibrium bosonization which allows one to study exactly low-dimensional systems of interacting electrons under far from equilibrium conditions. These methods can be applied to a large variety of experimentally relevant systems. 3. With J.T. Chalker we have developed the theory of electron equilibration in quantum Hall edge states, which agreed qualitatively with the experimental observations by the LPN/CNRS group. A remarkable feature of these experiments was the formation of non-equilibrium steady states. Our theory provided a description of these states. 4. I have developed a new numerical DMRG-based method which allows one to study quantum Hall phases in systems of rotating bosons. This method makes it possible to do calculations with much larger systems then it is possible with exact diagonalization. Later I extended this method (in collaboration) to Fractional Chern insulators. 5. I have studied (in collaboration) the phase diagram of rotating bosons in a highly anisotropic trap, which shows transitions between different vortex-lattice states. |
Exploitation Route | the theoretical and numerical methods that I developed can be used to study other systems. |
Sectors | Other |
Description | the results of my work have benefited a research community working in the field of condensed matter and cold atom systems. |
Description | collaboration with Prof. J.T. Chalker, Oxford University |
Organisation | University of Oxford |
Department | Department of Physics |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | common papers, discussion |
Collaborator Contribution | common papers, discussions |
Impact | common papers, see publications |
Start Year | 2007 |
Description | partnership with LPN/CNRS group of F. Pierre |
Organisation | National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS) |
Country | France |
Sector | Academic/University |
PI Contribution | discussion with the members of the group of their experiments |
Collaborator Contribution | the group contributed experimental data, discussions |
Impact | publications related to experiments done by this group |
Start Year | 2009 |
Title | DMRG for quantum Hall effect |
Description | I have developed a new numerical method (based on DMRG) and software, which allows one to study quantum Hall physics in bosonic systems whose size is much larger than that can be studied using exact diagonalization methods. This software is free and currently available upon request. |
Type Of Technology | Physical Model/Kit |
Year Produced | 2007 |
Impact | Later we have extended my code (in collaboration with Zhao Liu and Emil Bergholtz) to study new states of matter - Fractional Chern Insulators and their excitations. Our work provided evidence for this phases in certain lattice models. Application of DMRG-based methods in quantum Hall systems has now become a standard technique. This is in part due to the fact that with my software I have been able to demonstrate the capability of these methods and their advantages in comparison to exact diagonalization. |