Arianna Montorsi - Politecnico di Torino #
Hidden order beneath the gapped phases of low dimensional fermionic systems #
<p>The parity order hidden in the Mott insulating phase of 1D bosonic gases was 
observed 
via 
high-resolution imaging in optical lattices  [1]. In the fermionic case, it was shown 
in [2] 
that spin and charge parity orders characterize the two gapped phases of the 1D 
Hubbard 
model, suggesting also the possible detection of pairs of fermions with opposite 
spins  on 
neighboring sites in the Luther Emery phase. The discoveries can be casted into a 
general 
result obtained in [3], stating that long-range order is present in every gapped 
phase of one 
dimensional fermionic systems. It is captured by two-point correlators of appropriate 
charge 
and/or spin operators of nonlocal type. At least one of them remains asymptotically 
finite in 
each gapped phase, vanishing at the transition.</p>
<p>
We discuss the above findings and give some preliminary result about their 
generalization to the two-dimensional case.
</p>
<br/>
In collaboration with M. Roncaglia
<br/>
<br/>
<b>References</b>
<p>[1] M. Endres et al., Science 334 200 (2011)</p>
<p>[2] A. Montorsi, and M. Roncaglia, Phys. Rev. Lett. 109, 236404 (2012)</p>
<p>[3] L. Barbiero, A. Montorsi, and M. Roncaglia, "How hidden orders 
generate gaps in 1D fermionic systems", preprint arxiv:1302.6136</p>