Universality in fast quantum quenches

Sumit R. Das, Damián A. Galante, Robert C. Myers

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


Abstract: We expand on the investigation of the universal scaling properties in the early time behaviour of fast but smooth quantum quenches in a general d-dimensional conformal field theory deformed by a relevant operator of dimension Δ with a time-dependent coupling. The quench consists of changing the coupling from an initial constant value λ1 by an amount of the order of δλ to some other final value λ2, over a time scale δt. In the fast quench limit where δt is smaller than all other length scales in the problem, δt ≪ λ1 1/(Δ − d), λ2 1/(Δ − d), δλ1/(Δ − d), the energy (density) injected into the system scales as δℰ ∼ (δλ)2(δt)d− 2Δ. Similarly, the change in the expectation value of the quenched operator at times earlier than the endpoint of the quench scales as (Formula presented.), with further logarithmic enhancements in certain cases. While these results were first found in holographic studies, we recently demonstrated that precisely the same scaling appears in fast mass quenches of free scalar and free fermionic field theories. As we describe in detail, the universal scaling refers to renormalized quantities, in which the UV divergent pieces are consistently renormalized away by subtracting counterterms derived with an adiabatic expansion. We argue that this scaling law is a property of the conformal field theory at the UV fixed point, valid for arbitrary relevant deformations and insensitive to the details of the quench protocol. Our results highlight the difference between smooth fast quenches and instantaneous quenches where the Hamiltonian abruptly changes at some time.

Original languageEnglish
Article number167
Pages (from-to)1-69
Number of pages69
JournalJournal of High Energy Physics
Issue number2
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2015, The Author(s).


  • Effective field theories
  • Gauge-gravity correspondence
  • Holography and condensed matter physics (AdS/CMT)

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


Dive into the research topics of 'Universality in fast quantum quenches'. Together they form a unique fingerprint.

Cite this