Shinsei Ryu
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View article: Discrete time crystals detected by time-translation twist
Discrete time crystals detected by time-translation twist Open
We introduce a boundary condition twisted by time translation as a novel probe to characterize dynamical phases in periodically driven (Floquet) quantum systems. Inspired by twisted boundary conditions in equilibrium systems, this approach…
View article: Driven nonunitary dynamics of quantum critical systems
Driven nonunitary dynamics of quantum critical systems Open
We investigate the interplay between unitary and non-unitary driven many-body dynamics in (1+1)-dimensional quantum critical systems described by conformal field theory (CFT). By formulating a coherent state approach, we demonstrate that t…
View article: Higher-Form Anomalies on Lattices
Higher-Form Anomalies on Lattices Open
Higher-form symmetry in a tensor product Hilbert space is always emergent: the symmetry generators become genuinely topological only when the Gauss law is energetically enforced at low energies. In this paper, we present a general method f…
View article: Wilson-Loop-Ideal Bands and General Idealization
Wilson-Loop-Ideal Bands and General Idealization Open
Quantum geometry is universally bounded from below by Wilson-loop windings. In this work, we define an isolated set of bands to be Wilson-loop-ideal, if their quantum metric saturates the Wilson-loop lower bound. The definition naturally i…
View article: Non-equilibrating a black hole with inhomogeneous quantum quench
Non-equilibrating a black hole with inhomogeneous quantum quench Open
A bstract We study quantum quench processes in (1+1)-dimensional conformal field theory (CFT) in which the initial thermal equilibrium (Gibbs) state is time-evolved by spatially inhomogeneous Hamiltonians, the so-called Möbius and sine-squ…
View article: Higher Structures on Boundary Conformal Manifolds: Higher Berry Phase and Boundary Conformal Field Theory
Higher Structures on Boundary Conformal Manifolds: Higher Berry Phase and Boundary Conformal Field Theory Open
We introduce the notion of higher Berry connection and curvature in the space of conformal boundary conditions in (1+1)d conformal field theories (CFT), related to each other by exactly marginal boundary deformations, forming a "boundary c…
View article: Entanglement transitions in structured and random nonunitary Gaussian circuits
Entanglement transitions in structured and random nonunitary Gaussian circuits Open
We study measurement-induced phase transitions in quantum circuits consisting of kicked Ising models with postselected weak measurements, whose dynamics can be mapped onto a classical dynamical system. For a periodic (Floquet) non-unitary …
View article: Monotonicity of the RG flow in an emergent dual holography of a worldsheet nonlinear <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>σ</mml:mi></mml:math> model
Monotonicity of the RG flow in an emergent dual holography of a worldsheet nonlinear model Open
Based on the renormalization group (RG) flow of worldsheet bosonic string theory, we construct an effective holographic dual description of the target space theory identifying the RG scale with the emergent extra dimension. This results in…
View article: Non-linear sigma models for non-Hermitian random matrices in symmetry classes AI <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mo>†</mml:mo> </mml:msup> </mml:mrow> </mml:math> and AII <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mo>†</mml:mo> </mml:msup> </mml:mrow> </mml:math>
Non-linear sigma models for non-Hermitian random matrices in symmetry classes AI and AII Open
Symmetry of non-Hermitian matrices underpins many physical phenomena. In particular, chaotic open quantum systems exhibit universal bulk spectral correlations classified on the basis of time-reversal symmetry (TRS ), coinciding wit…
View article: Chiral Instabilities in Driven-Dissipative Quantum Liquids
Chiral Instabilities in Driven-Dissipative Quantum Liquids Open
We investigate the nonequilibrium dynamics of periodically driven Tomonaga-Luttinger liquids (TLLs) coupled to a thermal bath using a Floquet-Lindblad approach. When the coupling to the bath satisfies detailed balance, we obtain a conditio…
View article: Gauge theory and mixed state criticality
Gauge theory and mixed state criticality Open
In mixed quantum states, the notion of symmetry is divided into two types: strong and weak symmetry. While spontaneous symmetry breaking (SSB) for a weak symmetry is detected by two-point correlation functions, SSB for a strong symmetry is…
View article: Field theory of non-Hermitian disordered systems
Field theory of non-Hermitian disordered systems Open
The interplay between non-Hermiticity and disorder gives rise to unique universality classes of Anderson transitions. Here, we develop a field-theoretical description of non-Hermitian disordered systems based on fermionic replica nonlinear…
View article: Non-linear sigma models for non-Hermitian random matrices in symmetry classes AI$^{\dagger}$ and AII$^{\dagger}$
Non-linear sigma models for non-Hermitian random matrices in symmetry classes AI$^{\dagger}$ and AII$^{\dagger}$ Open
Symmetry of non-Hermitian matrices underpins many physical phenomena. In particular, chaotic open quantum systems exhibit universal bulk spectral correlations classified on the basis of time-reversal symmetry$^{\dagger}$ (TRS$^{\dagger}$),…
View article: Multi wavefunction overlap and multi entropy for topological ground states in (2+1) dimensions
Multi wavefunction overlap and multi entropy for topological ground states in (2+1) dimensions Open
Multi-wavefunction overlaps -- generalizations of the quantum mechanical inner product for more than two quantum many-body states -- are valuable tools for studying many-body physics. In this paper, we investigate the multi-wavefunction ov…
View article: Bridging two quantum quench problems — local joining quantum quench and Möbius quench — and their holographic dual descriptions
Bridging two quantum quench problems — local joining quantum quench and Möbius quench — and their holographic dual descriptions Open
A bstract We establish an equivalence between two different quantum quench problems, the joining local quantum quench and the Möbius quench, in the context of (1 + 1)-dimensional conformal field theory (CFT). Here, in the former, two initi…
View article: Entanglement entropy in lattice models with quantum metric
Entanglement entropy in lattice models with quantum metric Open
We revisit the connection between entanglement entropy and quantum metric in topological lattice systems, and provide an elegant and concise proof of this connection. In gapped two-dimensional lattice models with well-defined tight-binding…
View article: Higher Berry Phase from Projected Entangled Pair States in (2+1) dimensions
Higher Berry Phase from Projected Entangled Pair States in (2+1) dimensions Open
We consider families of invertible many-body quantum states in $d$ spatial dimensions that are parameterized over some parameter space $X$. The space of such families is expected to have topologically distinct sectors classified by the coh…
View article: Higher Berry Connection for Matrix Product States
Higher Berry Connection for Matrix Product States Open
In one spatial dimension, families of short-range entangled many-body quantum states, parameterized over some parameter space, can be topologically distinguished and classified by topological invariants built from the higher Berry phase --…
View article: Floquet engineered inhomogeneous quantum chaos in critical systems
Floquet engineered inhomogeneous quantum chaos in critical systems Open
We study universal chaotic dynamics of a large class of periodically driven critical systems described by spatially inhomogeneous conformal field theories. By employing an effective curved spacetime approach, we show that the onset of quan…
View article: Higher Hall conductivity from a single wave function: Obstructions to symmetry-preserving gapped edge of (2+1)D topological order
Higher Hall conductivity from a single wave function: Obstructions to symmetry-preserving gapped edge of (2+1)D topological order Open
A (2+1)D topological ordered phase with U(1) symmetry may or may not have a symmetric gapped edge state, even if both thermal and electric Hall conductivity are vanishing. It is recently discovered that there are "higher" versions of Hall …
View article: Monotonicity of RG flow in emergent dual holography of worldsheet nonlinear $σ$ model
Monotonicity of RG flow in emergent dual holography of worldsheet nonlinear $σ$ model Open
Based on the renormalization group (RG) flow of worldsheet bosonic string theory, we construct an effective holographic dual description of the target space theory identifying the RG scale with the emergent extra dimension. This results in…
View article: Scrambling and recovery of quantum information in inhomogeneous quenches in two-dimensional conformal field theories
Scrambling and recovery of quantum information in inhomogeneous quenches in two-dimensional conformal field theories Open
We study various quantum quench processes induced by the Möbius/sine-square deformation of the Hamiltonian in two-dimensional conformal field theories starting from the thermofield double state in the two copies of the Hilbert space. These…
View article: Multipartite entanglement in two-dimensional chiral topological liquids
Multipartite entanglement in two-dimensional chiral topological liquids Open
The multipartite entanglement structure for the ground states of two-dimensional (2D) topological phases is an interesting albeit not well-understood question. Utilizing the bulk-boundary correspondence, the calculation of tripartite entan…
View article: Higher bracket structure of density operators in Weyl fermion systems and topological insulators
Higher bracket structure of density operators in Weyl fermion systems and topological insulators Open
We study the algebraic structure of electron density operators in gapless Weyl fermion systems in $d=3,5,7,\cdots$ spatial dimensions and in topological insulators (without any protecting symmetry) in $d=4,6,8,\cdots$ spatial dimensions. T…
View article: Extracting Higher Central Charge from a Single Wave Function
Extracting Higher Central Charge from a Single Wave Function Open
A (2+1)D topologically ordered phase may or may not have a gappable edge, even if its chiral central charge c_ is vanishing. Recently, it was discovered that a quantity regarded as a "higher" version of chiral central charge gives a furthe…
View article: Spectral sum rules reflect topological and quantum-geometric invariants
Spectral sum rules reflect topological and quantum-geometric invariants Open
Topological invariants are fundamental characteristics reflecting global properties of quantum systems, yet their exploration has predominantly been limited to the static (DC) transport and transverse (Hall) channel. In this work, we exten…
View article: Nonequilibrium thermodynamics perspectives for the monotonicity of the renormalization group flow
Nonequilibrium thermodynamics perspectives for the monotonicity of the renormalization group flow Open
We investigate the monotonicity of the renormalization group (RG) flow from the perspectives of nonequilibrium thermodynamics. Applying the Martin-Siggia-Rose formalism to the Wilsonian RG transformation, we incorporate the RG flow equatio…
View article: Nonequilibrium thermodynamics perspectives for the monotonicity of the renormalization group flow
Nonequilibrium thermodynamics perspectives for the monotonicity of the renormalization group flow Open
We investigate the monotonicity of the renormalization group (RG) flow from the perspectives of nonequilibrium thermodynamics. Applying the Martin-Siggia-Rose formalism to the Wilsonian RG transformation, we incorporate the RG flow equatio…
View article: Bridging two quantum quench problems -- local joining quantum quench and Möbius quench -- and their holographic dual descriptions
Bridging two quantum quench problems -- local joining quantum quench and Möbius quench -- and their holographic dual descriptions Open
We establish an equivalence between two different quantum quench problems, the joining local quantum quench and the Möbius quench, in the context of $(1+1)$-dimensional conformal field theory (CFT). Here, in the former, two initially decou…
View article: Inhomogeneous Quantum Quenches of Conformal Field Theory with Boundaries
Inhomogeneous Quantum Quenches of Conformal Field Theory with Boundaries Open
We develop a method to calculate generic time-dependent correlation functions for inhomogeneous quantum quenches in (1+1)-dimensional conformal field theory (CFT) induced by sudden Hamiltonian deformations that modulate the energy density …