| 1. |
- Ahufinger, V., et al.
(författare)
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Disordered ultracold atomic gases in optical lattices : A case study of Fermi-Bose mixtures
- 2005
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 72:6
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Tidskriftsartikel (refereegranskat)abstract
- We present a review of properties of ultracold atomic Fermi-Bose mixtures in inhomogeneous and random optical lattices. In the strong interacting limit and at very low temperatures, fermions form, together with bosons or bosonic holes, composite fermions. Composite fermions behave as a spinless interacting Fermi gas, and in the presence of local disorder they interact via random couplings and feel effective random local potential. This opens a wide variety of possibilities of realizing various kinds of ultracold quantum disordered systems. In this paper we review these possibilities, discuss the accessible quantum disordered phases, and methods for their detection. The discussed quantum phases include Fermi glasses, quantum spin glasses, “dirty†superfluids, disordered metallic phases, and phases involving quantum percolation.
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| 2. |
- Diehl, S., et al.
(författare)
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Quantum states and phases in driven open quantum systems with cold atoms
- 2008
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Ingår i: Nature Physics. - : Nature Publishing Group. - 1745-2473 .- 1745-2481. ; 4:11, s. 878-883
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Tidskriftsartikel (refereegranskat)abstract
- An open quantum system, the time evolution of which is governed by a master equation, can be driven into a given pure quantum state by an appropriate design of the coupling between the system and the reservoir. This provides a route towards preparing many-body states and non-equilibrium quantum phases by quantum-reservoir engineering. Here, we discuss the example of a driven dissipative Bose–Einstein condensate of bosons and of paired fermions, where atoms in an optical lattice are coupled to a bath of Bogoliubov excitations and the atomic current represents local dissipation. In the absence of interactions, the lattice gas is driven into a pure state with long-range order. Weak interactions lead to a weakly mixed state, which in three dimensions can be understood as a depletion of the condensate, and in one and two dimensions exhibits properties reminiscent of a Luttinger liquid or a Kosterlitz–Thouless critical phase at finite temperature, with the role of the ’finite temperature’ taken by the interactions.
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| 3. |
- Kantian, A., et al.
(författare)
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Atomic Color Superfluid via Three-Body Loss
- 2009
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 103:24
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Tidskriftsartikel (refereegranskat)abstract
- Large three-body loss rates in a three-component Fermi gas confined in an optical lattice can dynamically prevent atoms from tunneling so as to occupy a lattice site with three atoms. This effective constraint not only suppresses the occurrence of actual loss events, but stabilizes BCS-pairing phases by suppressing the formation of trions. We study the effect of the constraint on the many-body physics using bosonization and density matrix renormalization group techniques, and also investigate the full dissipative dynamics including loss for the example of 6Li.
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| 4. |
- Kantian, A, et al.
(författare)
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Atomic lattice excitons : from condensates to crystals
- 2007
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 9:11, s. 407-407
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Tidskriftsartikel (refereegranskat)abstract
- We discuss atomic lattice excitons (ALEs), bound particle–hole pairs formed by fermionic atoms in two bands of an optical lattice. Such a system provides a clean set-up, with tunable masses and interactions, to study fundamental properties of excitons including exciton condensation. We also find that for a large effective mass ratio between particles and holes, effective long-range interactions can mediate the formation of an exciton crystal, for which superfluidity is suppressed. Using a combination of mean-field treatments, bosonized theory based on a Born–Oppenheimer approximation, and one-dimensional (1D) numerical computation, we discuss the properties of ALEs under varying conditions, and discuss in particular their preparation and measurement.
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| 5. |
- Kantian, A., et al.
(författare)
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η Condensate of Fermionic Atom Pairs via Adiabatic State Preparation
- 2010
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 104:24
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Tidskriftsartikel (refereegranskat)abstract
- We discuss how an η condensate, corresponding to an exact excited eigenstate of the Fermi-Hubbard model, can be produced with cold atoms in an optical lattice. Using time-dependent density matrix renormalization group methods, we analyze a state preparation scheme beginning from a band insulator state in an optical superlattice. This state can act as an important test case, both for adiabatic preparation methods and the implementation of the many-body Hamiltonian, and measurements on the final state can be used to help detect associated errors.
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| 6. |
- Kraus, B., et al.
(författare)
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Preparation of entangled states by quantum Markov processes
- 2008
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 78:4
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the possibility of using a dissipative process to prepare a quantum system in a desired state. We derive for any multipartite pure state a dissipative process for which this state is the unique stationary state and solve the corresponding master equation analytically. For certain states, such as the cluster states, we use this process to show that the jump operators can be chosen quasilocally, i.e. they act nontrivially only on a few, neighboring qubits. Furthermore, the relaxation time of this dissipative process is independent of the number of subsystems. We demonstrate the general formalism by considering arbitrary matrix-product states or projected entangled pair states. In particular, we show that the ground state of the Affleck-Kennedy-Lieb-Tasaki model can be prepared employing a quasi-local dissipative process.
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| 7. |
- Massel, F., et al.
(författare)
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Dynamics of an impurity in a one-dimensional lattice
- 2013
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 15:4
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Tidskriftsartikel (refereegranskat)abstract
- We study the non-equilibrium dynamics of an impurity in a harmonic trap that is kicked with a well-defined quasi-momentum, and interacts with a bath of free fermions or interacting bosons in a one-dimensional lattice configuration. Using numerical and analytical techniques we investigate the full dynamics beyond linear response, which allows us to quantitatively characterize states of the impurity in the bath for different parameter regimes. These vary from a tightly bound molecular state in a strongly interacting limit to a polaron (dressed impurity) and a free particle for weak interactions, with composite behaviour in the intermediate regime. These dynamics and different parameter regimes should be readily realizable in systems of cold atoms in optical lattices.
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| 8. |
- Morrison, S, et al.
(författare)
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Physical replicas and the Bose glass in cold atomic gases
- 2008
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- We study cold atomic gases in a disorder potential and analyse the correlations between different systems subjected to the same disorder landscape. Such independent copies with the same disorder landscape are known as replicas. While, in general, these are not accessible experimentally in condensed matter systems, they can be realized using standard tools for controlling cold atomic gases in an optical lattice. Of special interest is the overlap function which represents a natural order parameter for disordered systems and is a correlation function between the atoms of two independent replicas with the same disorder. We demonstrate an efficient measurement scheme for the determination of this disorder-induced correlation function. As an application, we focus on the disordered Bose–Hubbard model and determine the overlap function within the perturbation theory and a numerical analysis. We find that the measurement of the overlap function allows for the identification of the Bose-glass phase in certain parameter regimes.
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| 9. |
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| 10. |
- Sanpera, A., et al.
(författare)
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Atomic Fermi-Bose Mixtures in Inhomogeneous and Random Lattices : From Fermi Glass to Quantum Spin Glass and Quantum Percolation
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 93:4
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Tidskriftsartikel (refereegranskat)abstract
- We investigate strongly interacting atomic Fermi-Bose mixtures in inhomogeneous and random optical lattices. We derive an effective Hamiltonian for the system and discuss its low temperature physics. We demonstrate the possibility of controlling the interactions at local level in inhomogeneous but regular lattices. Such a control leads to the achievement of Fermi glass, quantum Fermi spin-glass, and quantum percolation regimes involving bare and/or composite fermions in random lattices.
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