Correlations at PT-Symmetric Quantum Critical Point

Area of Science:

• Quantum physics
• Condensed matter theory
• Non-Hermitian systems

Background:

• Investigating PT-symmetric quantum systems reveals unique phases and critical behaviors.
• Exceptional points mark transitions between PT-symmetric and symmetry-broken phases.
• Understanding Fermi gases in non-Hermitian settings is crucial for novel quantum phenomena.

Purpose of the Study:

• To analyze the properties of a PT-symmetric Fermi gas at an exceptional point.
• To explore the impact of non-Hermiticity on spectral properties and entanglement.
• To investigate the role of interactions in PT-symmetric Fermi gases.

Main Methods:

• Theoretical analysis of a PT-symmetric Fermi gas model.
• Calculation of low-energy spectrum and fermionic Green's function.
• Examination of ground state entanglement entropy and correlation length.

Main Results:

• The low-energy spectrum remains linear, mimicking Hermitian systems.
• Fermionic Green's function exhibits power-law decay, modified by the quantum Zeno effect.
• Ground state entanglement entropy saturates due to non-Hermitian correlation length.
• Interactions drive the system into PT-symmetry broken or protected phases.

Conclusions:

• Quantum criticality can be masked in non-Hermitian systems.
• The study challenges universality concepts in non-Hermitian quantum physics.
• Non-Hermitian effects significantly alter expected behaviors of Fermi gases.