A quantum critical system described at low energy by a conformal field theory (CFT) and subjected to a time-periodic boundary drive displays multiple dynamical regimes, depending on the drive frequency. We compute the behavior of quantities including the entanglement entropy and Loschmidt echo, confirming analytic predictions from field theory by exact numerics on the transverse field Ising model and demonstrate universality by adding nonintegrable perturbations. The dynamics naturally separate into three regimes: a slow-driving limit, which has an interpretation as multiple quantum quenches with amplitude corrections from CFT; a fast-driving limit, in which the system behaves as though subject to a single quantum quench; and a crossover regime displaying heating. The universal Floquet dynamics in all regimes can be understood using a combination of boundary CFT and Kibble-Zurek scaling arguments.A quantum critical system described at low energy by a conformal field theory (CFT) and subjected to a time-periodic boundary drive displays multiple dynamical regimes, depending on the drive frequency. We compute the behavior of quantities including the entanglement entropy and Loschmidt echo, confirming analytic predictions from field theory by exact numerics on the transverse field Ising model and demonstrate universality by adding nonintegrable perturbations. The dynamics naturally separate into three regimes: a slow-driving limit, which has an interpretation as multiple quantum quenches with amplitude corrections from CFT; a fast-driving limit, in which the system behaves as though subject to a single quantum quench; and a crossover regime displaying heating. The universal Floquet dynamics in all regimes can be understood using a combination of boundary CFT and Kibble-Zurek scaling arguments.

arXiv:1701.05899Physical Review LettersJun 29, 201749 citations

Real-time correlation function of Floquet conformal fields

M. Skou Andersen, Frederik Nørfjand, Nikolaj Thomas Zinner

Conformal field theories (CFT) play an important role in quantum field theories as they allow for exact studies that are hard to access without the conformal symmetries in place. A remarkable recent development is the application of conformal field theory to periodically driven systems, the so-called Floquet-driven CFTs. A number of recent works have found that there are classes of periodically driven ( $1+1$ )-dimensional CFTs that can be analytically solved, and that show both heating and nonheating phases, as well as unusual properties in terms of information scrambling. Hitherto, most results have focused on the dynamics of such models at stroboscopic times, i.e., samples taken at each period of the time evolution. In this paper, we consider time evolution at arbitrary real times and derive formulas for the exact time propagation of heating and nonheating classes of Floquet-driven CFTs. This requires a subtle treatment of nonstroboscopic time that leads to different interpretations in terms of curved space-time dynamics in these systems compared to previous results in the literature.Conformal field theories (CFT) play an important role in quantum field theories as they allow for exact studies that are hard to access without the conformal symmetries in place. A remarkable recent development is the application of conformal field theory to periodically driven systems, the so-called Floquet-driven CFTs. A number of recent works have found that there are classes of periodically driven ($1+1$)-dimensional CFTs that can be analytically solved, and that show both heating and nonheating phases, as well as unusual properties in terms of information scrambling. Hitherto, most results have focused on the dynamics of such models at stroboscopic times, i.e., samples taken at each period of the time evolution. In this paper, we consider time evolution at arbitrary real times and derive formulas for the exact time propagation of heating and nonheating classes of Floquet-driven CFTs. This requires a subtle treatment of nonstroboscopic time that leads to different interpretations in terms of curved space-time dynamics in these systems compared to previous results in the literature.

arXiv:2011.08494Physical review. D/Physical review. D.Mar 10, 202117 citations

Nonunitary Conformal Field Theories with Boundary

양버들

Jan 1, 19970 citations

Non-relativistic Floquet Conformal Field Theory

Diptarka Das, Sumit R. Das, Arnab Kundu +1 more

We develop a formalism for studying Floquet dynamics for systems with non-relativistic conformal invariance in d spatial dimensions. Our analysis indicates the existence of two dynamical phases, hyperbolic and elliptic, separated by a parabolic transition surface. We demonstrate this by studying the fidelity of the driven state and the expectation value of a conformal generator in the many body ground state during the drive. Stroboscopically, they behave exponentially in the hyperbolic phase, show oscillatory behavior in the elliptic phase, and exhibit power-law on the transition surface. Our analysis is completely universal and can be directly applied to several systems including trapped fermions near unitarity and resonant anyons. The former can provide experimental signatures of these dynamical phases. We also comment on a holographic perspective of such driven non-relativistic CFTs and demonstrate that the hyperbolic phase is associated with a timelike stationary-limit surface, such as an ergosphere, in the bulk, while the parabolic phase corresponds to an extremal Killing horizon.We develop a formalism for studying Floquet dynamics for systems with non-relativistic conformal invariance in d spatial dimensions. Our analysis indicates the existence of two dynamical phases, hyperbolic and elliptic, separated by a parabolic transition surface. We demonstrate this by studying the fidelity of the driven state and the expectation value of a conformal generator in the many body ground state during the drive. Stroboscopically, they behave exponentially in the hyperbolic phase, show oscillatory behavior in the elliptic phase, and exhibit power-law on the transition surface. Our analysis is completely universal and can be directly applied to several systems including trapped fermions near unitarity and resonant anyons. The former can provide experimental signatures of these dynamical phases. We also comment on a holographic perspective of such driven non-relativistic CFTs and demonstrate that the hyperbolic phase is associated with a timelike stationary-limit surface, such as an ergosphere, in the bulk, while the parabolic phase corresponds to an extremal Killing horizon.

arXiv:2607.27668Jul 30, 20260 citations

Physics of conformal field theories

Yevgeny Kats

Jan 1, 20100 citations

1+1

)-dimensional CFTs that can be analytically solved, and that show both heating and nonheating phases, as well as unusual properties in terms of information scrambling. Hitherto, most results have focused on the dynamics of such models at stroboscopic times, i.e., samples taken at each period of the time evolution. In this paper, we consider time evolution at arbitrary real times and derive formulas for the exact time propagation of heating and nonheating classes of Floquet-driven CFTs. This requires a subtle treatment of nonstroboscopic time that leads to different interpretations in terms of curved space-time dynamics in these systems compared to previous results in the literature.