ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

május 13. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba
és
online a Microsoft Teams-ben
<https://teams.microsoft.com/l/meetup-join/19%3ae1a26210676841cdbb27bb01cf353392%40thread.tacv2/1652349290587?context=%7b%22Tid%22%3a%226a3548ab-7570-4271-91a8-58da00697029%22%2c%22Oid%22%3a%22c7eaf7d2-684b-4597-b217-6a9121400219%22%7d>

Dóra Balázs (BME Elm. Fiz.):
Correlations at PT-symmetric quantum critical point

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)

Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor