The halon: a quasiparticle featuring critical charge fractionalization

Abstract

The halon is a special critical state of an impurity in a quantum-critical environment. The hallmark of the halon physics is that a well-defined integer charge gets fractionalized into two parts: a microscopic core with half-integer charge and a critically large halo carrying a complementary charge of $\pm 1/2$. The halon phenomenon emerges when the impurity--environment interaction is fine-tuned to the vicinity of a boundary quantum critical point (BQCP), at which the energies of two quasiparticle states with adjacent integer charges approach each other. The universality class of such BQCP is captured by a model of pseudo-spin-$1/2$ impurity coupled to the quantum-critical environment, in such a way that the rotational symmetry in the pseudo-spin $xy$-plane is respected, with a small local "magnetic" field along the pseudo-spin $z$-axis playing the role of control parameter driving the system away from the BQCP. On the approach to BQCP, the half-integer projection of the pseudo-spin on its $z$-axis gets delocalized into a halo of critically divergent radius, capturing the essence of the phenomenon of charge fractionalization. With large-scale Monte Carlo simulations, we confirm the existence of halons---and quantify their universal features---in O(2) and O(3) quantum critical systems.

arXiv comment18 pages, 13 figures

References in corpus (33)

• Many-Body Physics with Ultracold Gases
• Probing the Superfluid to Mott Insulator Transition at the Single Atom Level
• Experimental realization of a long-range antiferromagnet in the Hubbard model with ultracold atoms
• Observation of antiferromagnetic correlations in the Hubbard model with ultracold atoms
• Short-range quantum magnetism of ultracold fermions in an optical lattice
• The `Higgs' Amplitude Mode at the Two-Dimensional Superfluid-Mott Insulator Transition
• Fermi-Polaron: Diagrammatic Monte Carlo for Divergent Sign-Alternating Series
• Monte Carlo study of two-dimensional Bose-Hubbard model
• The superconductor-insulator transition in 2D dirty boson systems
• Visibility of the Amplitude (Higgs) Mode in Condensed Matter
• Quantum Impurity in a Nearly Critical Two Dimensional Antiferromagnet
• Ultra-precise holographic beam shaping for microscopic quantum control
• Impurity Quantum Phase Transitions
• Quantum impurity dynamics in two-dimensional antiferromagnets and superconductors
• Deconfined criticality flow in the Heisenberg model with ring-exchange interactions
• Spectral functions of the Higgs mode near two-dimensional quantum critical points
• Deconfined criticality, runaway flow in the two-component scalar electrodynamics and weak first-order superfluid-solid transitions
• The Higgs mode in a two-dimensional superfluid
• Spin-Excitation-Instability-Induced Quantum Phase Transitions in Double-Layer Quantum Hall Systems
• Quantum phase transitions in the Bose-Fermi Kondo model
• Fate of the Higgs mode near quantum criticality
• Phase Diagram of Commensurate Two-Dimensional Disordered Bose Hubbard Model
• Universal Conductivity in a Two-Dimensional Superfluid-to-Insulator Quantum Critical System
• Comprehensive quantum Monte Carlo study of the quantum critical points in planar dimerized/quadrumerized Heisenberg models
• Higgs amplitude mode in the vicinity of a $(2+1)$-dimensional quantum critical point
• Universal Properties of the Higgs Resonance in (2+1)-Dimensional U(1) Critical Systems
• Static hole in a critical antiferromagnet: field-theoretic renormalization group
• The Massive Goldstone (Higgs) mode in two-dimensional ultracold atomic lattice systems
• Trapping Collapse
• Trapping Centers at the Superfluid-Mott-insulator Criticality: Transition between Charge-quantized States
• Mobile impurity near the superfluid-Mott insulator quantum critical point in two dimensions
• Critical behavior of an impurity at the boson superfluid-Mott insulator transition
• Quantized Magnetic Flux and the Magneto-halon Effect in a Critical Superconductor

Cited by in corpus (4)

• Finite-size Scaling of O($n$) Systems at the Upper Critical Dimensionality
• Deconfined critical point in a doped random quantum Heisenberg magnet
• Graphical Representations and Worm Algorithms for the O($N$) Spin Model
• Even-Odd effect of an Spin-S impurity coupled to a quantum critical system