Giant number-parity effect leading to spontaneous symmetry breaking in finite-size quantum spin models

• URL: http://arxiv.org/abs/2412.15493v1
• Date: Fri, 20 Dec 2024 02:14:08 GMT
• Title: Giant number-parity effect leading to spontaneous symmetry breaking in finite-size quantum spin models
• Authors: Filippo Caleca, Saverio Bocini, Fabio Mezzacapo, Tommaso Roscilde,
• Abstract summary: Spontaneous symmetry breaking occurs in a many-body system governed by a symmetric Hamiltonian. We show that SSB can be observed in emphfinite-size quantum spin systems.
• Score: 0.0
• License:
• Abstract: Spontaneous symmetry breaking (SSB) occurs when a many-body system governed by a symmetric Hamiltonian, and prepared in a symmetry-broken state by the application of a field coupling to its order parameter $O$, retains a finite $O$ value even after the field is switched off. SSB is generally thought to occur only in the thermodynamic limit $N\to \infty$ (for $N$ degrees of freedom). In this limit, the time to restore the symmetry once the field is turned off, either via thermal or quantum fluctuations, is expected to diverge. Here we show that SSB can also be observed in \emph{finite-size} quantum spin systems, provided that three conditions are met: 1) the ground state of the system has long-range correlations; 2) the Hamiltonian conserves the (spin) parity of the order parameter; and 3) $N$ is odd. Using a combination of analytical arguments and numerical results (based on time-dependent variational Monte Carlo and rotor+spin-wave theory), we show that SSB on finite-size systems can be achieved via a quasi-adiabatic preparation of the ground state -- which, in U(1)-symmetric systems, is shown to require a symmetry breaking field vanishing over time scales $\tau \sim O(N)$. In these systems, the symmetry-broken state exhibits spin squeezing with Heisenberg scaling.

Related papers

• Controlling Symmetries and Quantum Criticality in the Anisotropic Coupled-Top Model [32.553027955412986]
  We investigate the anisotropic coupled-top model, which describes the interactions between two large spins along both $x-$ and $y-$directions. We can manipulate the system's symmetry, inducing either discrete $Z$ or continuous U(1) symmetry. The framework provides an ideal platform for experimentally controlling symmetries and investigating associated physical phenomena.
  arXiv  Detail & Related papers  (2025-02-13T15:14:29Z)
• Non-Abelian entanglement asymmetry in random states [0.0]
  We find that for any symmetry group, the average entanglement asymmetry vanishes in the thermodynamic limit when the subsystem is smaller than its complement. For larger subsystem sizes, the entanglement asymmetry displays a logarithmic scaling with a fixed coefficient by the dimension of the group.
  arXiv  Detail & Related papers  (2024-11-20T14:11:07Z)
• Exactly solvable models for fermionic symmetry-enriched topological phases and fermionic 't Hooft anomaly [33.49184078479579]
  The interplay between symmetry and topological properties plays a very important role in modern physics. How to realize all these fermionic SET (fSET) phases in lattice models remains to be a difficult open problem.
  arXiv  Detail & Related papers  (2024-10-24T19:52:27Z)
• Strong-to-weak spontaneous symmetry breaking meets average symmetry-protected topological order [17.38734393793605]
  We propose a new class of phases, termed the double ASPT phase, which emerges from a nontrivial extension of these two orders. This new phase is absent from prior studies and cannot exist in conventional closed systems.
  arXiv  Detail & Related papers  (2024-10-17T16:36:53Z)
• Entanglement asymmetry and quantum Mpemba effect in the XY spin chain [0.0]
  Entanglement asymmetry is a quantity introduced to measure how much a symmetry is broken in a part of an extended quantum system. We study the entanglement asymmetry at equilibrium taking the ground state of the XY spin chain. We find that the power law governing symmetry restoration depends discontinuously on whether the initial state is critical or not.
  arXiv  Detail & Related papers  (2023-10-11T14:10:53Z)
• Emergence of non-Abelian SU(2) invariance in Abelian frustrated fermionic ladders [37.69303106863453]
  We consider a system of interacting spinless fermions on a two-leg triangular ladder with $pi/2$ magnetic flux per triangular plaquette. Microscopically, the system exhibits a U(1) symmetry corresponding to the conservation of total fermionic charge, and a discrete $mathbbZ$ symmetry. At the intersection of the three phases, the system features a critical point with an emergent SU(2) symmetry.
  arXiv  Detail & Related papers  (2023-05-11T15:57:27Z)
• Scalable spin squeezing from spontaneous breaking of a continuous symmetry [0.0]
  In systems of $S=1/2$ or qubits, the combination of the suppression of fluctuations along one direction and of the persistence of transverse magnetization leads to spin squeezing. Our findings open the door to the adiabatic preparation of strongly spin-squeezed states in a large variety of quantum many-body devices including e.g. optical lattice clocks.
  arXiv  Detail & Related papers  (2022-02-17T11:41:30Z)
• SYK meets non-Hermiticity II: measurement-induced phase transition [16.533265279392772]
  We analytically derive the effective action in the large-$N$ limit and show that an entanglement transition is caused by the symmetry breaking in the enlarged replica space. We also verify the large-$N$ critical exponents by numerically solving the Schwinger-Dyson equation.
  arXiv  Detail & Related papers  (2021-04-16T17:55:08Z)
• Long-range-ordered phase in a quantum Heisenberg chain with interactions beyond nearest neighbors [0.0]
  cavity mediated infinite range interactions can induce fast scrambling in a Heisenberg $XXZ$ spin chain. We analyze the kaleidoscope of quantum phases that emerge in this system from the interplay of these interactions.
  arXiv  Detail & Related papers  (2021-03-07T05:20:52Z)
• Fermion and meson mass generation in non-Hermitian Nambu--Jona-Lasinio models [77.34726150561087]
  We investigate the effects of non-Hermiticity on interacting fermionic systems. We do this by including non-Hermitian bilinear terms into the 3+1 dimensional Nambu--Jona-Lasinio (NJL) model.
  arXiv  Detail & Related papers  (2021-02-02T13:56:11Z)
• Thermalization processes induced by quantum monitoring in multi-level systems [0.0]
  We study the heat statistics of a multi-level $N$-dimensional quantum system monitored by a sequence of projective measurements. The late-time, properties of the heat characteristic function are analyzed in the thermodynamic limit of a high, ideally infinite, number $M$ of measurements.
  arXiv  Detail & Related papers  (2020-12-30T16:14:05Z)

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.