Phase transitions as a manifestation of spontaneous unitarity violation

• URL: http://arxiv.org/abs/2209.04272v1
• Date: Fri, 9 Sep 2022 12:32:13 GMT
• Title: Phase transitions as a manifestation of spontaneous unitarity violation
• Authors: Jasper van Wezel
• Abstract summary: We argue that singling out a global choice for the ordered state is in fact forbidden under unitary time evolution. We argue that the observation of phase transitions in our everyday world presents a manifestation of the unitarity of quantum dynamics itself being spontaneously broken.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Spontaneous symmetry breaking is well understood under equilibrium conditions as a consequence of the singularity of the thermodynamic limit. How a single global orientation of the order parameter dynamically emerges from an initially symmetric state during a phase transition, however, is not captured by this paradigm. Here, we present a series of symmetry arguments suggesting that singling out a global choice for the ordered state is in fact forbidden under unitary time evolution, even in the presence of an environment and infinitesimal symmetry breaking perturbrations. We thus argue that the observation of phase transitions in our everyday world presents a manifestation of the unitarity of quantum dynamics itself being spontaneously broken. We argue that this agrees with the observation that Schr\"odinger's time dependent equation is rendered unstable for macroscopic objects owing to the same singular thermodynamic limit that affects equilibrium configurations.

Related papers

• Measurement-induced entanglement transition in chaotic quantum Ising chain [42.87502453001109]
  We study perturbations that break the integrability and/or the symmetry of the model, as well as modifications in the measurement protocol, characterizing the resulting chaos and lack of integrability through the Dissipative Spectral Form Factor (DSFF) We show that while the measurement-induced phase transition and its properties appear broadly insensitive to lack of integrability and breaking of the $bbZ$ symmetry, a modification of the measurement basis from the transverse to the longitudinal direction makes the phase transition disappear altogether.
  arXiv  Detail & Related papers  (2024-07-11T17:39:29Z)
• Entanglement phase transition due to reciprocity breaking without measurement or post-selection [59.63862802533879]
  EPT occurs for a system undergoing purely unitary evolution. We analytically derive the entanglement entropy out of and at the critical point for the $l=1$ and $l/N ll 1$ case.
  arXiv  Detail & Related papers  (2023-08-28T14:28:59Z)
• General theory for discrete symmetry-breaking equilibrium states [0.0]
  Spontaneous symmetry-breaking in phase transitions occurs when the system Hamiltonian is symmetric under a certain transformation. We show that when a discrete symmetry is spontaneously broken in a quantum system, the time evolution necessarily conserves two additional and non-commuting quantities.
  arXiv  Detail & Related papers  (2023-03-31T12:52:36Z)
• 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)
• Spontaneous symmetry breaking in non-steady modes of open quantum many-body systems [0.0]
  We consider spontaneous symmetry breaking in non-steady modes of an open quantum many-body system. For a dissipative spin model, it is shown that the most coherent mode exhibits a transition from a disordered phase to a symmetry-broken ordered phase.
  arXiv  Detail & Related papers  (2022-12-19T09:45:44Z)
• Topological transitions with continuously monitored free fermions [68.8204255655161]
  We show the presence of a topological phase transition that is of a different universality class than that observed in stroboscopic projective circuits. We find that this entanglement transition is well identified by a combination of the bipartite entanglement entropy and the topological entanglement entropy.
  arXiv  Detail & Related papers  (2021-12-17T22:01:54Z)
• Observation of Time-Crystalline Eigenstate Order on a Quantum Processor [80.17270167652622]
  Quantum-body systems display rich phase structure in their low-temperature equilibrium states. We experimentally observe an eigenstate-ordered DTC on superconducting qubits. Results establish a scalable approach to study non-equilibrium phases of matter on current quantum processors.
  arXiv  Detail & Related papers  (2021-07-28T18:00:03Z)
• Quotient symmetry protected topological phenomena [0.0]
  We show that topological phenomena can be stable over a large part of parameter space even when the bulk is strictly speaking in a trivial phase of matter. Although the Haldane phase is then adiabatically connected to a product state, we show that characteristic phenomena -- edge modes, entanglement degeneracies and bulk phase transitions -- remain parametrically stable.
  arXiv  Detail & Related papers  (2021-02-17T19:00:04Z)
• Exceptional Dynamical Quantum Phase Transitions in Periodically Driven Systems [0.0]
  We show that spontaneous symmetry breaking can occur at a short-time regime. Our results open up research for hitherto unknown phases in short-time regimes.
  arXiv  Detail & Related papers  (2020-12-22T04:04:56Z)
• Analog cosmological reheating in an ultracold Bose gas [58.720142291102135]
  We quantum-simulate the reheating-like dynamics of a generic cosmological single-field model in an ultracold Bose gas. Expanding spacetime as well as the background oscillating inflaton field are mimicked in the non-relativistic limit. The proposed experiment has the potential of exploring the evolution up to late times even beyond the weak coupling regime.
  arXiv  Detail & Related papers  (2020-08-05T18:00:26Z)
• Deconstructing effective non-Hermitian dynamics in quadratic bosonic Hamiltonians [0.0]
  We show that stability-to-instability transitions may be classified in terms of a suitably generalized $mathcalPmathcalT$ symmetry. We characterize the stability phase diagram of a bosonic analogue to the Kitaev-Majorana chain under a wide class of boundary conditions. Our analysis also reveals that boundary conditions that support Majorana zero modes in the fermionic Kitaev chain are precisely the same that support stability in the bosonic chain.
  arXiv  Detail & Related papers  (2020-03-06T19:30:51Z)

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.