Exited-state quantum phase transitions in constrained systems

• URL: http://arxiv.org/abs/2412.04240v1
• Date: Thu, 05 Dec 2024 15:23:08 GMT
• Title: Exited-state quantum phase transitions in constrained systems
• Authors: Jakub Novotný, Pavel Stránský, Pavel Cejnar,
• Abstract summary: We extend the standard theory of Exited-State Quantum Phase Transitions (ESQPTs) We adopt the method of Lagrange multipliers to find all stationary points and their properties directly from the Hamiltonian constrained by an arbitrary number of integrals of motion. We also elaborate the Holstein-Primakoff mapping, used to eliminate one degree of freedom in bosonic systems constrained by a conserved number of excitations.
• Score: 0.0
• License:
• Abstract: We extend the standard semiclassical theory of Exited-State Quantum Phase Transitions (ESQPTs), based on a classification of stationary points in the classical Hamiltonian, to constrained systems. We adopt the method of Lagrange multipliers to find all stationary points and their properties directly from the Hamiltonian constrained by an arbitrary number of integrals of motion, and demonstrate the procedure on an algebraic u(3) boson model with two independent constraints. We also elaborate the Holstein-Primakoff (HP) mapping, used to eliminate one degree of freedom in bosonic systems constrained by a conserved number of excitations, and address the fact that this mapping leads, in the classical limit, to a compact phase space with singular behaviour that conceals some stationary points at the phase space boundary. It is shown that the HP method reveals all ESQPTs only after constructing a complete atlas of different HP mappings.

Related papers

• Measurement phase transitions in the no-click limit as quantum phase transitions of a non-hermitean vacuum [77.34726150561087]
  We study phase transitions occurring in the stationary state of the dynamics of integrable many-body non-Hermitian Hamiltonians. We observe that the entanglement phase transitions occurring in the stationary state have the same nature as that occurring in the vacuum of the non-hermitian Hamiltonian.
  arXiv  Detail & Related papers  (2023-01-18T09:26:02Z)
• The frustration-free fully packed loop model [4.965221313169878]
  We consider a quantum fully packed loop model on the square lattice with a frustration-free projector Hamiltonian and ring-exchange interactions acting on plaquettes. We discuss how the boundary term fractures the Hilbert space into Krylov subspaces, and we prove that the Hamiltonian is ergodic within each subspace. We show that the spectrum is shown to be gapless in the thermodynamic limit with a trial state constructed by adding a twist to the ground state superposition.
  arXiv  Detail & Related papers  (2022-06-03T18:00:04Z)
• Non-Gaussian superradiant transition via three-body ultrastrong coupling [62.997667081978825]
  We introduce a class of quantum optical Hamiltonian characterized by three-body couplings. We propose a circuit-QED scheme based on state-of-the-art technology that implements the considered model.
  arXiv  Detail & Related papers  (2022-04-07T15:39:21Z)
• Topological fracton quantum phase transitions by tuning exact tensor network states [1.0753191494611891]
  Gapped fracton phases of matter generalize the concept of topological order. We employ an exact 3D quantum tensor-network approach to study a prototypical X cube fracton model.
  arXiv  Detail & Related papers  (2022-02-28T19:00:01Z)
• Excited-State Quantum Phase Transitions in the Anharmonic Lipkin-Meshkov-Glick Model I: Static Aspects [0.0]
  An anharmonic term in the Hamiltonian implies a second ESQPT of a different nature. We characterize this ESQPT using the mean field limit of the model. The new ESQPT, associated with the changes in the boundary of the finite Hilbert space of the system, can be properly described.
  arXiv  Detail & Related papers  (2022-02-23T10:53:05Z)
• Entanglement dynamics of spins using a few complex trajectories [77.34726150561087]
  We consider two spins initially prepared in a product of coherent states and study their entanglement dynamics. We adopt an approach that allowed the derivation of a semiclassical formula for the linear entropy of the reduced density operator.
  arXiv  Detail & Related papers  (2021-08-13T01:44:24Z)
• Quantum geometric tensor and quantum phase transitions in the Lipkin-Meshkov-Glick model [0.0]
  We build the classical Hamiltonian using Bloch coherent states and find its stationary points. They exhibit the presence of a ground state quantum phase transition, where a bifurcation occurs. For a sign change in one Hamiltonian parameter, the same phenomenon is observed in the highest energy state.
  arXiv  Detail & Related papers  (2021-05-24T21:48:34Z)
• Scaling limits of lattice quantum fields by wavelets [62.997667081978825]
  The renormalization group is considered as an inductive system of scaling maps between lattice field algebras. We show that the inductive limit of free lattice ground states exists and the limit state extends to the familiar massive continuum free field.
  arXiv  Detail & Related papers  (2020-10-21T16:30:06Z)
• Quantum and semi-classical aspects of confined systems with variable mass [0.3149883354098941]
  We explore the quantization of classical models with position-dependent mass terms constrained to a bounded interval in the canonical position. For a non-separable function $Pi(q,p)$, a purely quantum minimal-coupling term arises in the form of a vector potential for both the quantum and semi-classical models.
  arXiv  Detail & Related papers  (2020-05-28T18:50:24Z)
• Operator-algebraic renormalization and wavelets [62.997667081978825]
  We construct the continuum free field as the scaling limit of Hamiltonian lattice systems using wavelet theory. A renormalization group step is determined by the scaling equation identifying lattice observables with the continuum field smeared by compactly supported wavelets.
  arXiv  Detail & Related papers  (2020-02-04T18:04:51Z)
• From stochastic spin chains to quantum Kardar-Parisi-Zhang dynamics [68.8204255655161]
  We introduce the asymmetric extension of the Quantum Symmetric Simple Exclusion Process. We show that the time-integrated current of fermions defines a height field which exhibits a quantum non-linear dynamics.
  arXiv  Detail & Related papers  (2020-01-13T14:30:36Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.