The concept of confinement states that in certain systems the constituent particles are bound together by an interaction for which the strength increases with increasing particle separation. One of the consequences of this is that these individual particles cannot be observed directly. The most famous example of confinement is found in particle physics where baryons and mesons are produced by t...

We review our recent theoretical works on the the quantum spin Hall effect. First we compare edge states in various 2D systems, and see whether they are robust or fragile against perturbations. Through the comparisons we see the robust nature of edge states in 2D quantum spin Hall phases. We see how it is protected by the Z2 topological number, and reveal the nature of the Z2 topological number...

We treat the baryon as a composite system made out of a " core " of three quarks (as in the standard quark model) surrounded by a " sea " (of gluons and q ¯ q-pairs) which is specified by its total quantum numbers like flavor, spin and color. Specifically, we assume the sea to be a flavor octet with spin 0 but no color. The general wavefunction for spin 1/2 baryons with such a sea component is ...

We construct an exactly solvable spin-orbital model on a decorated square lattice that realizes an SU(2)-invariant Majorana spin liquid with parton Fermi surfaces, of the kind discussed recently by Biswas et al. [Phys. Rev. B 83, 245131 (2011)]. We find power-law spin correlations as well as power-law spin-nematic correlations with the same dominant 1/|r|3 envelope. The model is solvable also i...

The spin 1/2 baryons are pictured as a composite system made out of a " core " of three valence quarks (as in the simple quark model) surrounded by a " sea " (of gluon and q ¯ q pairs) which is specified by its total quantum numbers. We assume the sea is a SU (3) flavor octet with spin 0 or 1 but no color. This model, considered earlier, is used to obtain simultaneous fits for masses, magnetic ...

Recently, strong spin-orbit coupling with equal Rashba and Dresselhaus strength has been realized in neutral atomic Bose-Einstein condensates via a pair of Raman lasers. In this report, we investigate spin and field squeezing of the ground state in spin-orbit coupled Bose-Einstein condensate. By mapping the spin-orbit coupled BEC to the well-known quantum Dicke model, the Dicke type quantum pha...

We have observed sub-Poissonian spin correlations generated by collisionally induced spin mixing in a spin-1 Bose-Einstein condensate. We measure a quantum noise reduction of -7 dB (-10 dB corrected for detection noise) below the standard quantum limit for the corresponding coherent spin states. The spin fluctuations are detected as atom number differences in the spin states using fluorescent i...