Three `species' of Schrödinger cat states in an infinite-range spin model

Abstract

We explore a transverse-field Ising model that exhibits both spontaneous symmetry-breaking and eigenstate thermalization. Within its ferromagnetic phase, the exact eigenstates of the Hamiltonian of any large but finite-sized system are all Schrödinger cat states: superpositions of states with `up' and `down' spontaneous magnetization. This model exhibits two dynamical phase transitions {\it within} its ferromagnetic phase: In the lowest-temperature phase the magnetization can macroscopically oscillate between up and down. The relaxation of the magnetization is always overdamped in the remainder of the ferromagnetic phase, which is divided in to phases where the system thermally activates itself {\it over} the barrier between the up and down states, and where it quantum tunnels.

7 pages, added numerical results

References in corpus (6)

• Many-Body Physics with Ultracold Gases
• Thermalization and its mechanism for generic isolated quantum systems
• The distribution of the ratio of consecutive level spacings in random matrix ensembles
• Localization protected quantum order
• The Hilbert-glass transition: new universality of temperature-tuned many-body dynamical quantum criticality
• Dynamical quantum phase transitions in random spin chains

Cited by in corpus (7)

• Eigenstate Thermalization in Systems with Spontaneously Broken Symmetry
• Open system quantum annealing in mean field models with exponential degeneracy
• Spectral Form Factor of a Quantum Spin Glass
• Eigenstate localization in a many-body quantum system
• Eigenstate Thermalization and Spontaneous Symmetry Breaking in the One-Dimensional Transverse-Field Ising Model with Power-Law Interactions
• Spontaneous Symmetry Breaking, Spectral Statistics, and the Ramp
• Distinct Critical Behaviors from the Same State in Quantum Spin and Population Dynamics Perspectives