Speaker: Orion Ciftja

When: 12:00pm, Sep 15, 2021

Where: webinar/Zoom

Recording: [watch]


It has been conjectured that the Pauli Exclusion Principle alone may be responsible for a particular geometric arrangement of confined systems of identical fermions even when there is no interaction between them. These geometric structures, called Pauli crystals, are predicted for a two-dimensional (2D) system of free fermions under harmonic confinement. In this work, we pursue the possibility of this outcome. To this effect, we consider a theoretical model that may capture both qualitatively and quantitatively the key features of the abovementioned setup. The results for N = 3 and 6 particles show that the minimum energy configuration corresponds to and is in good quantitative agreement with the reported values of Pauli crystals seen in single-shot imaging data obtained via the configuration density technique. Numerical results for larger systems of N = 15 and 30 particles show that the crystalline configurations observed are not the same as the Pauli crystals. They are not even classical Wigner crystal structures that emerge should the confined charged particles interact with a Coulomb potential. This means that the current results raise doubts on the overall concept of Pauli fermions. An important question floated is whether such crystalline structures do really exist in a quantum system or whether they are artifacts of the methods used to analyze them.

Speaker Bio

Dr. Orion Ciftja is a Professor with the Department of Physics at Prairie View A&M University (PVAMU), where he leads the research efforts in Theoretical Condensed Matter Physics and Computational Physics. He received his Diploma degree from the International Centre of Theoretical Physics (ICTP), Trieste, Italy and both M.S. and Ph.D. degree from the International School of Advanced Studied (SISSA/ISAS), Trieste, Italy. Before joining PVAMU, he was a Postdoctoral Research Fellow at Ames Laboratory, Iowa State University and the University of Missouri, Columbia as well as a Visiting Assistant Professor at Texas A&M University (TAMU), College Station. Dr. Ciftja’s research interests include: 1) Strongly correlated electron systems, 2) Fractional quantum Hall effect, 3) Nanoscale semiconductor quantum dots, 4) Monte Carlo algorithms for quantum many-body systems, and 5) Nanoscale molecular magnetism. Dr. Ciftja has established several vigorous, externally funded, research programs covering a wide range of subjects pertaining to the research areas mentioned above while being at PVAMU. The current research was funded from NSF grants DMR-1705084 and DMR-2001980.