Publications by Natalia Chepiga

Critical properties of the quantum Ashkin-Teller chain with chiral perturbations

We investigate the nature of the phase transitions in the quantum Ashkin-Teller chain in the presence of chiral perturbations. We locate the Lifshitz line separating a region of direct chiral transitions from the region where the transition is through an i ...

Amer Physical Soc2023

Emergent U(1) symmetry in non-particle-conserving one-dimensional models

Frédéric Mila, Natalia Chepiga, Mohamed Zakaria Jouini, Loïc Jean Pierre Herviou

The properties of stable Luttinger liquid phases in models with a nonconserved number of particles are investigated. We study the Luttinger liquid phases in one-dimensional models of hard-core boson and spinless fermion chains where particles can be create ...

Amer Physical Soc2023

Eight-vertex criticality in the interacting Kitaev chain

Frédéric Mila, Natalia Chepiga

We show that including pairing and repulsion into the description of one-dimensional spinless fermions, as in the domain wall theory of commensurate melting or the interacting Kitaev chain, leads, for strong enough repulsion, to a line of critical points i ...

AMER PHYSICAL SOC2023

From SU(2)5 to SU(2)3 Wess-Zumino-Witten transitions in a frustrated spin-52 chain

Frédéric Mila, Natalia Chepiga

We investigate the properties of a frustrated spin-5/2 chain with next-nearest-neighbor two- and three-site interactions, with two questions in mind: the nature of the transition into the dimerized phase induced by the three-site interaction, and the possi ...

2022

Conformal and chiral phase transitions in Rydberg chains

Frédéric Mila, Natalia Chepiga, Ivo Aguiar Maceira

Using density matrix renormalization group simulations on open chains, we map out the wave vector in the incommensurate disordered phase of a realistic model of Rydberg chains with 1/r6 interactions, and we locate and characterize the points along the comm ...

AMER PHYSICAL SOC2022

Kibble-Zurek exponent and chiral transition of the period-4 phase of Rydberg chains

Frédéric Mila, Natalia Chepiga

Chains of Rydberg atoms have emerged as an amazing playground to study quantum physics in 1D. Playing with inter-atomic distances and laser detuning, one can in particular explore the commensurate-incommensurate transition out of density waves through the ...

Nature Research2021

Lifshitz point at commensurate melting of chains of Rydberg atoms

Frédéric Mila, Natalia Chepiga

The recent investigation of chains of Rydberg atoms has brought back the problem of commensurateincommensurate transitions into the focus of current research. In two-dimensional classical systems or in one-dimensional quantum systems, the commensurate melt ...

2021

Floating, critical, and dimerized phases in a frustrated spin-3/2 chain

Frédéric Mila, Natalia Chepiga

We study spontaneous dimerization and emergent criticality in a spin-3/2 chain with antiferromagnetic nearestneighbor J(1), next-nearest-neighbor J(2), and three-site J(3) interactions. In the absence of three-site interaction J(3), we provide evidence tha ...

2020

Spinon confinement and deconfinement in spin-1 chains

Frédéric Mila, Natalia Chepiga, Elisabeth Wybo

Motivated by the rich phase diagrams recently unveiled in frustrated spin-1 chains with competing next-nearest-neighbor and four-spin interactions, we investigate the nature of the elementary excitations of spin-1 chains in the vicinity of phase transition ...

2020

Dimerization and effective decoupling in two spin-1 generalizations of the spin-1/2 Majumdar-Ghosh chain

Frédéric Mila, Natalia Chepiga

We perform a systematic DMRG investigation of the two natural spin-1 generalizations of the spin-1/2 Majumdar-Ghosh chain, the spin-1 J(1)-J(2) Heisenberg chain, where J(2) is a next-nearest-neighbor Heisenberg coupling, and the spin-1 J(1)-J(3) model, whe ...

2019

DMRG investigation of constrained models: from quantum dimer and quantum loop ladders to hard-boson and Fibonacci anyon chains

Frédéric Mila, Natalia Chepiga

Motivated by the presence of Ising transitions that take place entirely in the singlet sector of frustrated spin-1/2 ladders and spin-1 chains, we study two types of effective dimer models on ladders, a quantum dimer model and a quantum loop model. Buildin ...

2019

Floating Phase versus Chiral Transition in a 1D Hard-Boson Model

Frédéric Mila, Natalia Chepiga

We investigate the nature of the phase transition between the period-three charge-density wave and the disordered phase of a hard-boson model proposed in the context of cold-atom experiments. Building on a density-matrix renormalization group algorithm tha ...

2019

Rigorous decoupling between edge states in frustrated spin chains and ladders

Frédéric Mila, Natalia Chepiga

2018

Dimerization and exotic criticality in spin-S chains

Natalia Chepiga

In this thesis we have studied the emergence of spontaneously dimerized phases in frustrated spin-S chains, with emphasis on the nature of the critical lines between the dimerized and non-dimerized phases. The main numerical method used in this thesis is t ...

EPFL2017

Controlling the Topological Sector of Magnetic Solitons in Exfoliated Cr1/3NbS2 Crystals

Frédéric Mila, Fengping Li, Natalia Chepiga

We investigate manifestations of topological order in monoaxial helimagnet Cr1/3NbS2 by performing transport measurements on ultrathin crystals. Upon sweeping the magnetic field perpendicularly to the helical axis, crystals thicker than one helix pitch (48 ...

2017

Exact zero modes in frustrated Haldane chains

Frédéric Mila, Natalia Chepiga

2017

Excitation spectrum and density matrix renormalization group iterations

Frédéric Mila, Natalia Chepiga

We show that, in certain circumstances, exact excitation energies appear as locally site-independent (or flat) modes if one records the excitation spectrum of the effective Hamiltonian while sweeping through the lattice in the variational matrix-product-st ...

2017

Dimerization transitions in spin-1 chains

Frédéric Mila, Natalia Chepiga

We study spontaneous dimerization transitions in a Heisenberg spin-1 chain with additional next-nearest-neighbor and three-site interactions using extensive numerical simulations and a conformal field-theory analysis. We show that the transition can be sec ...

2016

Spontaneous dimerization, critical lines, and short-range correlations in a frustrated spin-1 chain

Frédéric Mila, Natalia Chepiga

We report on a detailed investigation of the spin-1 J1−J2−J3 Heisenberg model, a frustrated model with nearest-neighbor coupling J1, next-nearest neighbor coupling J2, and a three-site interaction J3[(Si−1⋅Si)(Si⋅Si+1)+H.c.] previously studied in [Phys. Re ...

2016

Comment on “Frustration and multicriticality in the antiferromagnetic spin-1 chain”

Frédéric Mila, Natalia Chepiga

The phase diagram of the spin-1 chain with bilinear-biquadratic and next-nearest-neighbor interactions, recently investigated by Pixley, Shashi, and Nevidomskyy [Phys. Rev. B 90, 214426 (2014)], has been revisited in the light of results we have recently o ...

2016