Időpont:
2022. 05. 13. 10:15
Hely:
BME building F, seminar room of the Dept. of Theoretical Physics & Online
Előadó:
Balázs Dóra (BME)
A szeminárium részletei:
We consider a PT-symmetric Fermi gas with an exceptional point,
representing the critical point between PT-symmetric and symmetry
broken phases. The low energy spectrum remains linear in momentum
and is identical to that of a hermitian Fermi gas. The fermionic Green's
function decays in a power law fashion for large distances, as expected
from gapless excitations, albeit the exponent is reduced from −1 due to
the quantum Zeno effect. In spite of the gapless nature of the excitations,
the ground state entanglement entropy saturates to a finite value,
independent of the subsystem size due to the non-hermitian correlation
length intrinsic to the system. Attractive or repulsive interaction drives
the system into the PT-symmetry broken regime or opens up a gap and
protects PT-symmetry, respectively. Our results challenge the concept of
universality in non-hermitian systems, where quantum criticality can be
masked due to non-hermiticity.
[1]: B Dóra, D Sticlet, CP Moca: Phys. Rev. Lett. 128, 146804 (2022)