Haldane phases with ultracold fermionic atoms in double-well optical lattices

International audienceWe propose to realize one-dimensional topological phases protected by SU(N) symmetry using alkali or alkaline-earth atoms loaded into a bichromatic optical lattice. We derive a realistic model for this system and investigate it theoretically. Depending on the parity of N, two different classes of symmetry-protected topological (SPT) phases are stabilized at half-filling for physical parameters of the model. For even N, the celebrated spin-1 Haldane phase and its generalization to SU(N) are obtained with no local symmetry breaking. In stark contrast, at least for N=3, a new class of SPT phases, dubbed chiral Haldane phases, that spontaneously break inversion symmetry, emerges with a twofold ground-state degeneracy. The latter ground states with open-boundary conditions are characterized by different left and right boundary spins, which are related by conjugation. Our results show that topological phases are within close reach of the latest experiments on cold fermions in optical lattices

Entangling Two Individual Atoms of Different Isotopes via Rydberg Blockade

Quantum entanglement is crucial for simulating and understanding exotic physics of strongly correlated many-body systems, such as high--temperature superconductors, or fractional quantum Hall states. The entanglement of non-identical particles exhibits richer physics of strong many-body correlations and offers more opportunities for quantum computation, especially with neutral atoms where in contrast to ions the interparticle interaction is widely tunable by Feshbach resonances. Moreover, the inter-species entanglement forms a basis for the properties of various compound systems, ranging from Bose-Bose mixtures to photosynthetic light-harvesting complexes. So far, the inter-species entanglement has only been obtained for trapped ions. Here we report on the experimental realization of entanglement of two neutral atoms of different isotopes. A ${}^{87}\mathrm{Rb}$ atom and a ${}^{85}\mathrm{Rb}$ atom are confined in two single--atom optical traps separated by 3.8 $\mu$m. Creating a strong Rydberg blockade, we demonstrate a heteronuclear controlled--NOT (C--NOT) quantum gate and generate a heteronuclear entangled state, with raw fidelities $0.73 \pm 0.01$ and $0.59 \pm 0.03$, respectively. Our work, together with the technologies of single--qubit gate and C--NOT gate developed for identical atoms, can be used for simulating any many--body system with multi-species interactions. It also has applications in quantum computing and quantum metrology, since heteronuclear systems exhibit advantages in low crosstalk and in memory protection.Comment: 11 pages, 6 figure

A toy model for the dipolar-induced resonance in quasi-one-dimensional systems

We discuss the properties of the effective dipolar interaction for two particles tightly confined along a one-dimensional tube, stressing the emergence of a single dipolar-induced resonance in a regime for which two classical dipoles would just repel each other. We present a toy-model potential reproducing the main features of the effective interaction: a non-zero-range repulsive potential competing with an attractive contact term. The existence of a single resonance is confirmed analytically. The toy model is than generalized to investigate the interplay between dipolar and contact interaction, giving an intuitive interpretation of the resonance mechanism

Achieving high molecular conversion efficiency via a magnetic field pulse train

We investigate the process of production of ultracold molecules in an ultracold bosonic system with particle interaction via designing a magnetic field pulse train near a Feshbach resonance. This technique offers a high conversion efficiency up to 100% by tuning the pulse durations appropriately. The molecular conversion efficiency is related to the duration of each pulse, which can be derived analytically. It is found that the conversion efficiency is insensitive to the first pulse, highly sensitive to the second one, and very insensitive to the third one. The effects of particle interaction on conversion process are discussed as well.Physics, Condensed MatterSCI(E)EI0ARTICLE6null8