Natan Andrei
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View article: Two-channel Kondo behavior in the quantum XX chain with a boundary defect
Two-channel Kondo behavior in the quantum XX chain with a boundary defect Open
We demonstrate that a boundary defect in the single spin-$\frac{1}{2}$ quantum $XX$ chain exhibits two-channel Kondo physics. Due to the presence of the defect, the edge spin fractionalizes into two Majorana fermions, out of which one deco…
View article: Complete Boundary Phase Diagram of the Spin-$\frac{1}{2}$ XXZ Chain with Boundary Fields in the Anti-Ferromagnetic Gapped Regime
Complete Boundary Phase Diagram of the Spin-$\frac{1}{2}$ XXZ Chain with Boundary Fields in the Anti-Ferromagnetic Gapped Regime Open
We consider the spin $\frac{1}{2}$ XXZ chain with diagonal boundary fields and solve it exactly using Bethe ansatz in the gapped anti-ferromagnetic regime and obtain the complete phase boundary diagram. Depending on the values of the bound…
View article: Spin chain with non-Hermitian <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="script">PT</mml:mi></mml:math>-symmetric boundary couplings: Exact solution, dissipative Kondo effect, and phase transitions on the edge
Spin chain with non-Hermitian -symmetric boundary couplings: Exact solution, dissipative Kondo effect, and phase transitions on the edge Open
We construct an exactly solvable $\mathscr{PT}-$symmetric non-Hermitian model where a spin$-\frac{1}{2}$ isotropic quantum Heisenberg spin chain is coupled to two spin$-\frac{1}{2}$ Kondo impurities at its boundaries with coupling strength…
View article: Emergent boundary supersymmetry in a one dimensional superconductor
Emergent boundary supersymmetry in a one dimensional superconductor Open
The interplay between bulk properties and boundary conditions in one-dimensional quantum systems, gives rise to many intriguing phenomena. These include the emergence of zero energy modes which are of significant interest to a variety of f…
View article: Edge modes and boundary impurities in the anisotropic Heisenberg spin chain
Edge modes and boundary impurities in the anisotropic Heisenberg spin chain Open
We present a comprehensive analysis of boundary phenomena in a spin-$\frac{1}{2}$ anisotropic Heisenberg chain (XXZ-$\frac{1}{2}$) in the gapped antiferromagnetic phase, with a particular focus on the interplay between fractionalized spin-…
View article: The Kondo effect in the quantum XX spin chain
The Kondo effect in the quantum XX spin chain Open
We investigate the boundary phenomena that arise in a finite-size XX spin chain interacting through an XX interaction with a spin impurity located at its edge. Upon Jordan–Wigner transformation, the model is described by a quadratic …
View article: The Kondo effect in the quantum $XX$ spin chain
The Kondo effect in the quantum $XX$ spin chain Open
We investigate the boundary phenomena that arise in a finite-size $XX$ spin chain interacting through an $XX$ interaction with a spin$-\frac{1}{2}$ impurity located at its edge. Upon Jordan-Wigner transformation, the model is described by …
View article: Exact solution of a non-Hermitian PT -symmetric spin chain
Exact solution of a non-Hermitian PT -symmetric spin chain Open
We construct the exact solution of a non-Hermitian -symmetric isotropic Heisenberg spin chain with integrable boundary fields. We find that the system exhibits two types of phases named A and B . In the B type phase, the symmetry r…
View article: Exact solution of a non-Hermitian $\mathscr{PT}$-symmetric Heisenberg spin chain
Exact solution of a non-Hermitian $\mathscr{PT}$-symmetric Heisenberg spin chain Open
We construct the exact solution of a non-Hermitian $\mathscr{PT}$-symmetric isotropic Heisenberg spin chain with integrable boundary fields. We find that the system exhibits two types of phases we refer to as $A$ and $B$ phases. In the $B$…
View article: Boundary Quantum Phase Transitions in the Spin $\frac{1}{2}$ Heisenberg Chain with Boundary Magnetic Fields
Boundary Quantum Phase Transitions in the Spin $\frac{1}{2}$ Heisenberg Chain with Boundary Magnetic Fields Open
We consider the spin $\frac{1}{2}$ Heisenberg chain with boundary magnetic fields and analyze it using a combination of Bethe ansatz and density matrix renormalization group (DMRG) techniques. We show that the system exhibits several diffe…
View article: Rise and fall of Yu-Shiba-Rusinov bound states in charge-conserving <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>s</mml:mi></mml:math>-wave one-dimensional superconductors
Rise and fall of Yu-Shiba-Rusinov bound states in charge-conserving -wave one-dimensional superconductors Open
We re-examine the problem of a magnetic impurity coupled to a superconductor focusing on the role of quantum fluctuations. We study in detail, a system that consists of a one-dimensional charge conserving spin-singlet superconductor couple…
View article: Multiparticle Quantum Walks and Fisher Information in One-Dimensional Lattices
Multiparticle Quantum Walks and Fisher Information in One-Dimensional Lattices Open
Recent experiments on quantum walks (QWs) demonstrated a full control over the statistics-dependent walks of single particles and two particles in one-dimensional lattices. However, little is known about the general characterization of QWs…
View article: Roadmap on Atomtronics: State of the art and perspective
Roadmap on Atomtronics: State of the art and perspective Open
Atomtronics deals with matter-wave circuits of ultracold atoms manipulated through magnetic or laser-generated guides with different shapes and intensities. In this way, new types of quantum networks can be constructed in which coherent fl…
View article: Many-body wavefunctions for quantum impurities out of equilibrium
Many-body wavefunctions for quantum impurities out of equilibrium Open
We present a method for calculating the time-dependent many-body wavefunction\nthat follows a local quench. We apply the method to the voltage-driven\nnonequilibrium Kondo model to find the exact time-evolving wavefunction\nfollowing a que…
View article: Many-body wavefunctions for quantum impurities out of equilibrium. II. Charge fluctuations
Many-body wavefunctions for quantum impurities out of equilibrium. II. Charge fluctuations Open
We extend the general formalism discussed in the previous paper [A. B. Culver\nand N. Andrei, Phys. Rev. B 103, 195106 (2021)] to two models with charge\nfluctuations: the interacting resonant level model and the Anderson impurity\nmodel. …
View article: Many-body wavefunctions for quantum impurities out of equilibrium. I. The nonequilibrium Kondo model
Many-body wavefunctions for quantum impurities out of equilibrium. I. The nonequilibrium Kondo model Open
We present here the details of a method [A. B. Culver and N. Andrei, Phys. Rev. B 103, L201103 (2021)] for calculating the time-dependent many-body wavefunction that follows a local quench. We apply the method to the voltage-driven nonequi…
View article: Edge modes in one-dimensional topological charge conserving spin-triplet superconductors: Exact results from Bethe ansatz
Edge modes in one-dimensional topological charge conserving spin-triplet superconductors: Exact results from Bethe ansatz Open
Charge conserving spin singlet and spin triplet superconductors in one\ndimension are described by the $U(1)$ symmetric Thirring Hamiltonian. We solve\nthe model with open boundary conditions on the a finite line segment by means\nof the B…
View article: Roadmap on Atomtronics
Roadmap on Atomtronics Open
Atomtronics is an emerging field of quantum technology dealing with matter-wave circuits of ultra-cold atoms manipulated in magnetic or laser-generated guides of different shapes and intensity. Atomtronic circuits are promised to define qu…
View article: Roadmap on Atomtronics: State of the art and perspective
Roadmap on Atomtronics: State of the art and perspective Open
Atomtronics deals with matter-wave circuits of ultra-cold atoms manipulated through magnetic or laser-generated guides with different shapes and intensities. In this way, new types of quantum networks can be constructed, in which coherent …
View article: State of the art and perspective on Atomtronics
State of the art and perspective on Atomtronics Open
Atomtronics deals with matter-wave circuits of ultra-cold atoms manipulated through magnetic or laser-generated guides with different shapes and intensities. In this way, new types of quantum networks can be constructed, in which coherent …
View article: Nonperturbative Approach to the Nonequilibrium Kondo Model
Nonperturbative Approach to the Nonequilibrium Kondo Model Open
We present a nonperturbative method for calculating the time-dependent many body wavefunction that follows a local quench, and we use it to find the exact time evolution of the nonequilibrium Kondo model driven by a bias voltage. We show t…
View article: Nonperturbative approach to quench dynamics. II. Universal electric current of the nonequilibrium Kondo model
Nonperturbative approach to quench dynamics. II. Universal electric current of the nonequilibrium Kondo model Open
In the previous paper, we found a series expression for the average electric current following a quench in the nonequilibrium Kondo model driven by a bias voltage. Here, we evaluate the steady state current in the regimes of strong and wea…
View article: Nonperturbative approach to quench dynamics. II. Universal electric\n current of the nonequilibrium Kondo model
Nonperturbative approach to quench dynamics. II. Universal electric\n current of the nonequilibrium Kondo model Open
In the previous paper, we found a series expression for the average electric\ncurrent following a quench in the nonequilibrium Kondo model driven by a bias\nvoltage. Here, we evaluate the steady state current in the regimes of strong\nand …
View article: Nonperturbative approach to quench dynamics. I. Exact time evolution and steady state of the nonequilibrium Kondo model
Nonperturbative approach to quench dynamics. I. Exact time evolution and steady state of the nonequilibrium Kondo model Open
We present a nonperturbative method for calculating the time-dependent many body wavefunction that follows a local quench, and we use it to find the exact time evolution of the nonequilibrium Kondo model driven by a bias voltage. The metho…
View article: Quantum work of an optical lattice
Quantum work of an optical lattice Open
A classic example of a quantum quench concerns the release of a interacting\nBose gas from an optical lattice. The local properties of quenches such as this\nhave been extensively studied however the global properties of these\nnon-equilib…
View article: Loschmidt amplitude and work distribution in quenches of the sine-Gordon model
Loschmidt amplitude and work distribution in quenches of the sine-Gordon model Open
The Sine-Gordon - equivalently, the massive Thirring - Hamiltonian is ubiquitous in low-dimensional physics, with applications that range from cold atom and strongly correlated systems to quantum impurities. We study here its non-equilibri…
View article: Loschmidt Amplitude and Work Distribution in Quenches of the Sine-Gordon Model
Loschmidt Amplitude and Work Distribution in Quenches of the Sine-Gordon Model Open
The Sine-Gordon - equivalently, the massive Thirring - Hamiltonian is ubiquitous in low-dimensional physics, with applications that range from cold atom and strongly correlated systems to quantum impurities. We study here its non-equilibri…
View article: Quantum dot in interacting environments
Quantum dot in interacting environments Open
A quantum impurity attached to an interacting quantum wire gives rise to an\narray of of new phenomena. Using Bethe Ansatz we solve exactly models\ndescribing two geometries of a quantum dot coupled to an interacting quantum\nwire: a quant…
View article: Simplified Thermodynamics for Quantum Impurity Models
Simplified Thermodynamics for Quantum Impurity Models Open
Quantum impurity models play an important role in many areas of physics from condensed matter to AMO and quantum information. They are important models for many physical systems but also provide key insights to understanding much more comp…
View article: Quench Dynamics of the Gaudin-Yang Model
Quench Dynamics of the Gaudin-Yang Model Open
We study the quench dynamics of one dimensional bosons or fermion quantum gases with either attractive or repulsive contact interactions. Such systems are well described by the Gaudin-Yang model which turns out to be quantum integrable. We…