Even-harmonic generation through nonequilibrium steady-state symmetry breaking

• URL: http://arxiv.org/abs/2607.27847v1
• Date: Thu, 30 Jul 2026 08:25:45 GMT
• Title: Even-harmonic generation through nonequilibrium steady-state symmetry breaking
• Abstract summary: High-harmonic generation (HHG) in inversion-symmetric systems is typically restricted to odd harmonics by symmetry.<n>We show that this selection rule can be broken without modifying the underlying Hamiltonian.<n>Our results uncover a mechanism for even-harmonic generation that relies solely on nonequilibrium steady-state symmetry breaking.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: High-harmonic generation (HHG) in inversion-symmetric systems is typically restricted to odd harmonics by symmetry. Here, we show that this selection rule can be broken without modifying the underlying Hamiltonian. We investigate a boundary-driven Su-Schrieffer-Heeger (SSH) chain coupled to source and sink reservoirs and demonstrate that dissipative dynamics generates a nonequilibrium steady state carrying a finite DC current. While the SSH Hamiltonian retains inversion symmetry, the current-carrying steady-state density matrix does not, leading to the emergence of even harmonics in the emitted spectrum. Using a correlation-matrix approach based on the Lindblad master equation, we obtain the steady state and calculate the resulting HHG response. We find that the intensity of the even harmonics is directly controlled by the transport current, establishing a link between nonequilibrium charge transport and HHG selection rules. Our results uncover a mechanism for even-harmonic generation that relies solely on nonequilibrium steady-state symmetry breaking and provide a route to probing transport currents through ultrafast nonlinear spectroscopy in centrosymmetric quantum systems.

Related papers

• Symmetry Constrained Quantum Error Mitigation for the Schwinger Model [39.146761527401424]
  We exploit the parity and fermion-number symmetries of a gauge theory under depolarising noise.<n>We investigate symmetry verification under digital quantum simulation.
  arXiv  Detail & Related papers  (2026-08-21T13:49:11Z)
• Hydrodynamic tails in chaotic spin chains with quantum group symmetry [36.94429692322632]
  We show that quantum group symmetry provides a novel mechanism for anomalous hydrodynamics in chaotic systems.<n>We study the dynamics of local operators carrying $U(1)$ charge in non-integrable lattice models that also have quantum group symmetry.
  arXiv  Detail & Related papers  (2026-06-18T18:34:52Z)
• Magnetic domains stabilized by symmetry-protected zero modes [0.10923877073891443]
  We show strong non-ergodic behavior in the XX model on coupled chains.<n>Antiferromagnetic defects in the initial state and symmetry-breaking perturbations restore slow thermalization.<n>These results establish that degenerate, symmetry-protected subspaces can give rise to thermodynamically stable non-ergodic dynamics in experimentally accessible quantum systems.
  arXiv  Detail & Related papers  (2026-04-16T20:36:42Z)
• Average Equilibration Time for Gaussian Unitary Ensemble Hamiltonians [35.18016233072556]
  We study equilibration times in closed quantum systems using the framework of equilibration as dephasing.<n>We find that the equilibration time decreases with system size and timescales in the thermodynamic limit.<n>This unphysical result indicates that the true equilibration timescale of realistic chaotic many-body systems must be dominated by physical features not captured by random matrix ensembles.
  arXiv  Detail & Related papers  (2026-03-30T15:35:04Z)
• Asymmetric regularization mechanism for GAN training with Variational Inequalities [1.529943343419486]
  We formulate the training of generative adversarial networks (GANs) as a Nash equilibrium seeking problem.<n>We propose an asymmetric regularization mechanism based on the classic Tikhonov step and on a novel zero-centered gradient penalty.
  arXiv  Detail & Related papers  (2026-01-20T12:50:18Z)
• Nonlinear magnetization dynamics as a route to nonreciprocal phases, spin superfluidity, and analogue gravity [0.0]
  We show that balancing a dc drive against Gilbert damping stabilizes a chiral spin-superfluid limit cycle that spontaneously breaks spacetime-translation symmetry.<n>Long-wavelength magnons of opposite chirality acquire asymmetric dispersions and propagate direction-selectively, realizing a spin-supergravity diode.
  arXiv  Detail & Related papers  (2025-10-24T18:42:23Z)
• Realization of Trapped Ion Dynamics in the Strong-Field Regime and Non-Markovianity [33.781064984238775]
  We experimentally investigate the dynamics of a trapped ion where the Rabi frequency (Omega) approaches the vibrational mode frequency (nu)<n>Using quantum state tomography, we reconstruct the density matrix and track its evolution to assess non-Markovianity.<n>Our findings establish a pathway for using trapped-ion platforms to investigate non-Markovianity, coherent control, and the fundamental behavior of open quantum systems in extreme regimes.
  arXiv  Detail & Related papers  (2025-10-23T11:25:09Z)
• Parametric resonant enhancement of motional entanglement under optimal control: an analytical study [45.88028371034407]
  We study theoretically continuous-variable entanglement between the motional degrees of freedom of optically trapped massive particles coupled via the Coulomb interaction.<n>We perform a detailed analysis of the parametric resonance induced by temporal modulation of the coupling strength, based on the system's coupled nonlinear, nonhomogeneous dynamical equations.<n>We demonstrate that a stationary nonequilibrium entangled state is realized as a result of the competition between parametric gain and decoherence.
  arXiv  Detail & Related papers  (2025-10-21T09:01:19Z)
• A Clockwork Quantum: Symmetry, Noise, and the Emergence of Quantum Order [0.0]
  Noise-induced synchronization and coherence protection in open quantum systems is studied.<n>We show that symmetry in the noise correlations acts as a control parameter, protecting symmetric or antisymmetric modes.<n>These insights offer a unifying view of synchronization in classical and quantum regimes.
  arXiv  Detail & Related papers  (2025-07-25T14:59:03Z)
• Noise-resilient Edge Modes on a Chain of Superconducting Qubits [103.93329374521808]
  Inherent symmetry of a quantum system may protect its otherwise fragile states. We implement the one-dimensional kicked Ising model which exhibits non-local Majorana edge modes (MEMs) with $mathbbZ$ parity symmetry. MEMs are found to be resilient against certain symmetry-breaking noise owing to a prethermalization mechanism.
  arXiv  Detail & Related papers  (2022-04-24T22:34:15Z)
• Harmonic oscillator kicked by spin measurements: a Floquet-like system without classical analogous [62.997667081978825]
  The impulsive driving is provided by stroboscopic measurements on an ancillary degree of freedom. The dynamics of this system is determined in closed analytical form. We observe regimes with crystalline and quasicrystalline structures in phase space, resonances, and evidences of chaotic behavior.
  arXiv  Detail & Related papers  (2021-11-23T20:25:57Z)
• Fluctuation-Dissipation Relation from the Nonequilibrium Dynamics of a Nonlinear Open Quantum System [0.0]
  We show that equilibration implies an FDR for the anharmonic oscillator. We show that the net energy exchange vanishes after relaxation in the open system dynamics.
  arXiv  Detail & Related papers  (2020-02-18T16:18:25Z)

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.