Inhomogeneous quenches as state preparation in two-dimensional conformal field theories
Masahiro Nozaki, Kotaro Tamaoka, Mao Tian Tan
Abstract
The nonequilibrium process where the system does not evolve to the featureless state, that without quantum properties, is one of the new central objects in the nonequilibrium phenomena. In this paper, starting from the short-range entangled state in the two-dimensional conformal field theories (2D CFTs), the boundary state with a regularization, we evolve the system with the inhomogeneous Hamiltonians called Möbius/sine-square-deformed (SSD) ones. Regardless of the details of CFTs considered in this paper, during the Möbius evolution, the entanglement entropy exhibits the periodic motion called quantum revival. During SSD time evolution, except for some subsystems, in the large time regime, entanglement entropy and mutual information are approximated by those for the vacuum state. We argue the time regime for the subsystem to cool down to vacuum one is <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>t</a:mi><a:mn>1</a:mn></a:msub><a:mo>≫</a:mo><a:mi mathvariant="script">O</a:mi><a:mo stretchy="false">(</a:mo><a:mi>L</a:mi><a:msqrt><a:msub><a:mi>l</a:mi><a:mi>A</a:mi></a:msub></a:msqrt><a:mo stretchy="false">)</a:mo></a:math>, where <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:msub><f:mi>t</f:mi><f:mn>1</f:mn></f:msub></f:math>, <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mi>L</h:mi></h:math>, and <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:msub><j:mi>l</j:mi><j:mi>A</j:mi></j:msub></j:math> are time, system, and subsystem sizes. This finding suggests the inhomogeneous quench induced by the SSD Hamiltonian may be used as the preparation for the approximately vacuum state. We propose the gravity dual of the systems considered in this paper, furthermore, and generalize it. In addition to them, we discuss the relation between the inhomogeneous quenches and continuous multiscale entanglement renormalization ansatz (cMERA). Published by the American Physical Society 2024