All-optical background-free detection of ring currents by dynamical symmetry breaking high harmonic spectroscopy

Ofer Neufeld, Oren Cohen

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Excited atoms and molecules can carry long-lived currents that circulate in the microscopic media. From a quantum mechanical perspective, these currents can be understood as a coherent wave-packet comprising a superposition of bound-states that oscillates in time [1-3]. When the wave-packet has a non-zero angular momentum expectation value, ring-currents circulate in the medium. For instance, a hydrogen atom excited to a 2p-state with non-zero magnetic quantum number m (e.g. by interaction with circularly polarized light) carries a steady-state ring current [2]. More complex systems can also carry persistent ring currents, e.g. spin-orbit wave-packets in Xenon [4], or multi-electron wave-packets in larger molecules [1]. This phenomenon is general to any quantum system and is especially interesting because it occurs on the natural time-scale of electronic motion - attoseconds to femtoseconds. Understanding ring currents is thus fundamentally important for manipulating and controlling ultrafast processes on the nanoscale, including chemical bond formation and topologically protected surface currents [5], as well as for the generation of intense attosecond-duration magnetic fields [1,6]. However, ring currents are very difficult to detect, particularly in a time-resolved manner.

Original languageEnglish
Title of host publicationEuropean Quantum Electronics Conference, EQEC_2019
StatePublished - 2019
EventEuropean Quantum Electronics Conference, EQEC_2019 - Munich, United Kingdom
Duration: 23 Jun 201927 Jun 2019

Publication series

NameOptics InfoBase Conference Papers
VolumePart F143-EQEC 2019


ConferenceEuropean Quantum Electronics Conference, EQEC_2019
Country/TerritoryUnited Kingdom

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Mechanics of Materials


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