Colloquium: Photons and electrons as emergent phenomena

  title={Colloquium: Photons and electrons as emergent phenomena},
  author={Michael Levin and Xiao-Gang Wen},
  journal={Reviews of Modern Physics},
Recent advances in condensed-matter theory have revealed that new and exotic phases of matter can exist in spin models (or more precisely, local bosonic models) via a simple physical mechanism, known as ``string-net condensation.'' These new phases of matter have the unusual property that their collective excitations are gauge bosons and fermions. In some cases, the collective excitations can behave just like the photons, electrons, gluons, and quarks in our vacuum. This suggests that photons… 

Quantum ether: photons and electrons from a rotor model

We give an example of a purely bosonic model--a rotor model on the 3D cubic lattice--whose low energy excitations behave like massless U(1) gauge bosons and massless Dirac fermions. This model can be

Modern Physics of the Condensed State: Strong Correlations and Quantum Topology

The theme of this survey is the application of new ideas of uncommon quantum states to the physics of the condensed state, in particular, of solids, in the context of the contemporary field theory. A

Light-induced gauge fields for ultracold atoms

Different realized and proposed techniques for creating gauge potentials-both Abelian and non-Abelian-in atomic systems and their implication in the context of quantum simulation are reviewed.

Emergent gauge symmetries: making symmetry as well as breaking it

  • S. Bass
  • Physics
    Philosophical Transactions of the Royal Society A
  • 2021
Recent thinking on possible emergent gauge symmetries in particle physics is discussed, commenting also on Higgs phenomena and the vacuum energy or cosmological constant puzzle inEmergent gauge systems.

Atomic quantum simulation of dynamical gauge fields coupled to fermionic matter: from string breaking to evolution after a quench.

Using a Fermi-Bose mixture of ultracold atoms in an optical lattice, a quantum simulator is constructed for a U(1) gauge theory coupled to fermionic matter to investigate string breaking as well as the real-time evolution after a quench in gauge theories, which are inaccessible to classical simulation methods.

Topological Order : From Long-Range Entangled Quantum Matter to a Unified Origin of Light and Electrons

We review the progress in the last 20–30 years, duringwhichwe discovered that there aremany newphases ofmatter that are beyond the traditional Landau symmetry breaking theory. We discuss new

Ultracold quantum gases and lattice systems: quantum simulation of lattice gauge theories

Abelian and non‐Abelian gauge theories are of central importance in many areas of physics. In condensed matter physics, Abelian U(1) lattice gauge theories arise in the description of certain quantum

Quantum simulation of gauge potentials with cold atoms in optical lattices: a tunable platform for relativistic fermions and axions

We offer here a brief introduction to the idea of quantum simulations with cold atomic gases, with focus on the recent efforts towards artificial gauge potentials and fields. This is mainly intended

Symmetry Protected Topological phases of Quantum Matter

We describe recent progress in our understanding of the interplay between interactions, symmetry, and topology in states of quantum matter. We focus on a minimal generalization of the celebrated



Quantum order from string net condensations and origin of light and massless fermions

Recently, it was pointed out that quantum orders and the associated projective symmetry groups can produce and protect massless gauge bosons and massless fermions in local bosonic models. In this

Fermions, strings, and gauge fields in lattice spin models

We investigate the general properties of lattice spin models with emerging fermionic excitations. We argue that fermions always come in pairs and their creation operator always has a stringlike

String-net condensation: A physical mechanism for topological phases

We show that quantum systems of extended objects naturally give rise to a large class of exotic phases---namely topological phases. These phases occur when extended objects, called ``string-nets,''

Origin of gauge bosons from strong quantum correlations.

  • X. Wen
  • Physics
    Physical review letters
  • 2002
Through models, it is shown that the existence of light can simply be a phenomenon of quantum coherence in a system with many degrees of freedom.

Gauge Theory of elementary particle physics

This is a practical introduction to the principal ideas in gauge theory and their applications to elementary particle physics. It explains technique and methodology with simple exposition backed up

Quantum Mechanics of Fractional-Spin Particles

Composites formed from charged particles and vortices in (2+1)-dimensional models, or flux tubes in three-dimensional models, can have any (fractional) angular momentum. The statistics of these

Phase transitions in Abelian lattice gauge theories

Field theory of strings as a collective field theory of U(N) gauge fields

We develop a collective field theory of a U(N) gauge field, which involves gauge-invariant operators only. We treat gauge-invariant path-ordered phase factors as collective fields on string space.

Pyrochlore photons: The U ( 1 ) spin liquid in a S = 1 2 three-dimensional frustrated magnet

We study the $S=1/2$ Heisenberg antiferromagnet on the pyrochlore lattice in the limit of strong easy-axis exchange anisotropy. We find, using only standard techniques of degenerate perturbation