ITAMP Lunch Seminar

Speaker: Adrian Feiguin, (Northeastern University)

Date: Thursday, November 30th

Time: 12:00-1:00 pm

Includes Pizza.

Title: Spin incoherent behavior in strongly correlated low dimensional systems

Abstract: When electrons (or other quantum particles with an internal ``spin" degree of freedom) are confined in one spatial dimension, they loose their identity as individual particles. The excitations become collective modes carrying spin, and charge, with each degree of freedom being characterized by a different energy scale. While the basic theoretical understanding of spin-charge separation in one-dimension, known as ``Luttinger liquid theory'', has existed for some time, recently a previously unidentified regime of strongly interacting one-dimensional systems at finite temperature came to light: The ``spin-incoherent Luttinger liquid". This occurs when the temperature is larger than the characteristic spin energy scale. The key to establishing both Luttinger liquid behavior and spin-incoherent Luttinger liquid behavior in experiment is detailed knowledge of the spectral properties.

I will present a numerical study of the finite-temperature spectral properties of a one-dimensional fermionic gas in the spin-incoherent regime using the time-dependent density matrix renormalization group method.  This approach enables us to quantitatively handle the experimentally relevant and theoretically challenging ``crossover" regime between the Luttinger liquid and spin-incoherent Luttinger liquid limits. Finally, I will show that spin-incoherent behavior can be realized in the *ground-state* of model Hamiltonians, such as Hubbard ladders, and the Kondo lattice.

Location:  B-106 @ Center for Astrophysics (60 Garden Street)

Directions: After entering the lobby of the CfA, turn right to enter the hallway of the B building. In the hallway, turn right again, B-106 will be at the end of the hallway on the left side.