Abstract Recently, a non-trivial relation between the quasi-particle spectrum and entanglement entropy production was discovered in non-integrable quenches in the paramagnetic Ising quantum spin chain. Here we study the dynamics of analogous quenches in the quantum Potts spin chain. Tuning the parameters of the system, we observe a sudden increase in the entanglement production rate, which is shown to be related to the appearance of new quasiparticle excitations in the post-quench spectrum. Our results demonstrate the generality of the effect and support its interpretation as the non-equilibrium version of the well-known Gibbs paradox related to mixing entropy which appears in systems with a non-trivial quasi-particle spectrum.Abstract Recently, a non-trivial relation between the quasi-particle spectrum and entanglement entropy production was discovered in non-integrable quenches in the paramagnetic Ising quantum spin chain. Here we study the dynamics of analogous quenches in the quantum Potts spin chain. Tuning the parameters of the system, we observe a sudden increase in the entanglement production rate, which is shown to be related to the appearance of new quasiparticle excitations in the post-quench spectrum. Our results demonstrate the generality of the effect and support its interpretation as the non-equilibrium version of the well-known Gibbs paradox related to mixing entropy which appears in systems with a non-trivial quasi-particle spectrum.

arXiv:1810.05539Journal of Statistical Mechanics Theory and ExperimentJan 1, 201916 citations

Quantum Spin Chains with Residual Entropy

Bruno Nachtergaele

Springer eBooksJan 1, 19911 citation

Entanglement spreading after a geometric quench in quantum spin chains

Vincenzo Alba, Fabian Heidrich‐Meisner

We investigate the entanglement spreading in the anisotropic spin- $1/2$ Heisenberg $(XXZ)$ chain after a geometric quench. This corresponds to a sudden change of the geometry of the chain or, in the equivalent language of interacting fermions confined in a box trap, to a sudden increase of the trap size. The entanglement dynamics after the quench is associated with the ballistic propagation of a magnetization wave front. At the free fermion point ( $XX$ chain), the von Neumann entropy ${S}_{A}$ exhibits several intriguing dynamical regimes. Specifically, at short times a logarithmic increase is observed, similar to local quenches. This is accurately described by an analytic formula that we derive from heuristic arguments. At intermediate times partial revivals of the short-time dynamics are superposed with a power-law increase ${S}_{A}\ensuremath{\sim}{t}^{\ensuremath{\alpha}}$, with $\ensuremath{\alpha}<1$. Finally, at very long times a steady state develops with constant entanglement entropy, apart from oscillations. As expected, since the model is integrable, we find that the steady state is nonthermal, although it exhibits extensive entanglement entropy. We also investigate the entanglement dynamics after the quench from a finite to the infinite chain (sudden expansion). While at long times the entanglement vanishes, we demonstrate that its relaxation dynamics exhibits a number of scaling properties. Finally, we discuss the short-time entanglement dynamics in the $XXZ$ chain in the gapless phase. The same formula that describes the time dependence for the $XX$ chain remains valid in the whole gapless phase.We investigate the entanglement spreading in the anisotropic spin-$1/2$ Heisenberg $(XXZ)$ chain after a geometric quench. This corresponds to a sudden change of the geometry of the chain or, in the equivalent language of interacting fermions confined in a box trap, to a sudden increase of the trap size. The entanglement dynamics after the quench is associated with the ballistic propagation of a magnetization wave front. At the free fermion point ($XX$ chain), the von Neumann entropy ${S}_{A}$ exhibits several intriguing dynamical regimes. Specifically, at short times a logarithmic increase is observed, similar to local quenches. This is accurately described by an analytic formula that we derive from heuristic arguments. At intermediate times partial revivals of the short-time dynamics are superposed with a power-law increase ${S}_{A}\ensuremath{\sim}{t}^{\ensuremath{\alpha}}$, with $\ensuremath{\alpha}<1$. Finally, at very long times a steady state develops with constant entanglement entropy, apart from oscillations. As expected, since the model is integrable, we find that the steady state is nonthermal, although it exhibits extensive entanglement entropy. We also investigate the entanglement dynamics after the quench from a finite to the infinite chain (sudden expansion). While at long times the entanglement vanishes, we demonstrate that its relaxation dynamics exhibits a number of scaling properties. Finally, we discuss the short-time entanglement dynamics in the $XXZ$ chain in the gapless phase. The same formula that describes the time dependence for the $XX$ chain remains valid in the whole gapless phase.

arXiv:1402.2299Physical Review BAug 26, 201488 citations

Generalized entropy of the Heisenberg spin chain

Alexander Rudol'fovich Its, V. E. Korepin

Theoretical and Mathematical PhysicsSep 1, 20108 citations

Entanglement entropy dynamics of disordered quantum spin chains

Ferenc Iglói, Zsolt Szatmári, Yu‐Cheng Lin

By means of free fermionic techniques we study the time evolution of the entanglement entropy $\mathcal{S}(t)$ of a block of spins in the random transverse-field Ising chain after a sudden change of the parameters of the Hamiltonian. We consider global quenches, when the parameters are modified uniformly in space, as well as local quenches, when two disconnected blocks are suddenly joined together. For a noncritical final state, the dynamical entanglement entropy is found to approach a finite limiting value for both types of quenches. If the quench is performed to the critical state, the entropy grows for an infinite block as $\mathcal{S}(t)\ensuremath{\sim}\mathrm{ln}\mathrm{ln}t$. This type of ultraslow increase is explained through the strong disorder renormalization group method.By means of free fermionic techniques we study the time evolution of the entanglement entropy $\mathcal{S}(t)$ of a block of spins in the random transverse-field Ising chain after a sudden change of the parameters of the Hamiltonian. We consider global quenches, when the parameters are modified uniformly in space, as well as local quenches, when two disconnected blocks are suddenly joined together. For a noncritical final state, the dynamical entanglement entropy is found to approach a finite limiting value for both types of quenches. If the quench is performed to the critical state, the entropy grows for an infinite block as $\mathcal{S}(t)\ensuremath{\sim}\mathrm{ln}\mathrm{ln}t$. This type of ultraslow increase is explained through the strong disorder renormalization group method.

arXiv:1201.3695Physical Review BMar 12, 201288 citations

Entropy Production in Quantum Spin Systems

David Pierre Ruelle

arXiv:math-ph/0006006Communications in Mathematical PhysicsNov 1, 200190 citations

We investigate the entanglement spreading in the anisotropic spin-

1/2

Heisenberg

(XXZ)

chain after a geometric quench. This corresponds to a sudden change of the geometry of the chain or, in the equivalent language of interacting fermions confined in a box trap, to a sudden increase of the trap size. The entanglement dynamics after the quench is associated with the ballistic propagation of a magnetization wave front. At the free fermion point (

XX

chain), the von Neumann entropy

{S}_{A}

exhibits several intriguing dynamical regimes. Specifically, at short times a logarithmic increase is observed, similar to local quenches. This is accurately described by an analytic formula that we derive from heuristic arguments. At intermediate times partial revivals of the short-time dynamics are superposed with a power-law increase ${S}_{A}\ensuremath{\sim}{t}^{\ensuremath{\alpha}}$, with $\ensuremath{\alpha}<1$. Finally, at very long times a steady state develops with constant entanglement entropy, apart from oscillations. As expected, since the model is integrable, we find that the steady state is nonthermal, although it exhibits extensive entanglement entropy. We also investigate the entanglement dynamics after the quench from a finite to the infinite chain (sudden expansion). While at long times the entanglement vanishes, we demonstrate that its relaxation dynamics exhibits a number of scaling properties. Finally, we discuss the short-time entanglement dynamics in the

XXZ

chain in the gapless phase. The same formula that describes the time dependence for the

XX

chain remains valid in the whole gapless phase.

By means of free fermionic techniques we study the time evolution of the entanglement entropy

\mathcal{S}(t)

of a block of spins in the random transverse-field Ising chain after a sudden change of the parameters of the Hamiltonian. We consider global quenches, when the parameters are modified uniformly in space, as well as local quenches, when two disconnected blocks are suddenly joined together. For a noncritical final state, the dynamical entanglement entropy is found to approach a finite limiting value for both types of quenches. If the quench is performed to the critical state, the entropy grows for an infinite block as $\mathcal{S}(t)\ensuremath{\sim}\mathrm{ln}\mathrm{ln}t$. This type of ultraslow increase is explained through the strong disorder renormalization group method.