Jose L. Lado

Software

I develop scientific software of two kinds. The Python libraries solve families of Hamiltonians (tight-binding models, spin models) and can be used from any other Python code. The interactive programs are built on those libraries, so that a calculation can be set up by changing parameters in a window rather than by writing a script.

Everything is released under the GPL and is free to use in any project. Most of it is still under active development.

pyqula

Tight-binding models on quantum lattices, in any dimension: band structures, Fermi surfaces, spectral functions, topological invariants, mean-field interactions, superconductivity and non-collinear magnetism, with a few lines of Python each.

Six pyqula examples, each a few lines of code with its result: a non-unitary spin-triplet superconductor, a topological phase transition in an artificial superconductor, the bound state of a magnetic impurity in a superconductor, interaction-driven magnetism in a honeycomb nanoisland, the Hofstadter butterfly of a square lattice, and the Landau levels of a Dirac semimetal.
Six pyqula examples, each the full script and its result.

dmrgpy

Quantum many-body models with matrix product states, built on the ITensor library: ground states, excited states, and static and dynamical correlators of spin and fermionic chains.

Quantum Lattice

Tight-binding models, computed interactively: band structures, Fermi surfaces, spectral functions, topological invariants, local magnetization and local density of states, for systems with non-collinear magnetism, spin-orbit coupling, superconductivity and electronic interactions. Built on pyqula.

The Quantum Lattice system selection window, with buttons for 0D, 1D, 2D and 3D systems: islands, ribbons, Hofstadter butterflies, sheets, films, single impurities, multilayer graphene, transition metal dichalcogenides, twisted multilayer graphene and 3D crystals.
Quantum Lattice: choosing the system to compute.

SpinFlare

One-dimensional quantum many-body spin Hamiltonians, solved interactively with matrix product states: ground state magnetization, static and dynamical spin-spin correlators, and excited states. A chain of 100 quantum spins takes a few seconds.

The SpinFlare window beside a plot of the dynamical structure factor of a spin chain as a function of site and energy.
SpinFlare: the dynamical structure factor of an S=1 Heisenberg chain, showing the bulk spin gap and the fractionalized zero-energy edge modes.

Qutranpy

Quantum transport in a two-terminal geometry, with the Landauer and scattering matrix formalism. The Hamiltonians of the leads and of the scattering region can each be given exchange fields, a mass term, spin-orbit coupling or superconductivity. Built on the pygra library.

The Qutranpy window, with the parameters of the left lead, central region and right lead in columns, and sweeps in a Hamiltonian parameter, in energy and in the length of the scattering region.
Qutranpy: the parameters of the two leads and the central region.

Tranci

Electronic properties of transition metal atoms on surfaces, solved in the full many-body space of the d orbitals with the configuration interaction method, including crystal fields, spin-orbit coupling and electronic interactions. The results are written to a PDF: the operators projected onto the ground state manifold, the eigenstates, and how the levels evolve with each parameter.

The Tranci window: a single-shot or sweep calculation on the left, and the general, spin-orbit, crystal field and magnetic field parameters on the right.
Tranci: a single-shot calculation and its parameters.

Python libraries

pyqula

Tight-binding models on quantum lattices, in any dimension: band structures, Fermi surfaces, spectral functions, topological invariants, mean-field interactions, superconductivity and non-collinear magnetism, with a few lines of Python each.

Six pyqula examples, each a few lines of code with its result: a non-unitary spin-triplet superconductor, a topological phase transition in an artificial superconductor, the bound state of a magnetic impurity in a superconductor, interaction-driven magnetism in a honeycomb nanoisland, the Hofstadter butterfly of a square lattice, and the Landau levels of a Dirac semimetal.
Six pyqula examples, each the full script and its result.

dmrgpy

Quantum many-body models with matrix product states, built on the ITensor library: ground states, excited states, and static and dynamical correlators of spin and fermionic chains.

Interactive programs

Quantum Lattice

Tight-binding models, computed interactively: band structures, Fermi surfaces, spectral functions, topological invariants, local magnetization and local density of states, for systems with non-collinear magnetism, spin-orbit coupling, superconductivity and electronic interactions. Built on pyqula.

The Quantum Lattice system selection window, with buttons for 0D, 1D, 2D and 3D systems: islands, ribbons, Hofstadter butterflies, sheets, films, single impurities, multilayer graphene, transition metal dichalcogenides, twisted multilayer graphene and 3D crystals.
Quantum Lattice: choosing the system to compute.

SpinFlare

One-dimensional quantum many-body spin Hamiltonians, solved interactively with matrix product states: ground state magnetization, static and dynamical spin-spin correlators, and excited states. A chain of 100 quantum spins takes a few seconds.

The SpinFlare window beside a plot of the dynamical structure factor of a spin chain as a function of site and energy.
SpinFlare: the dynamical structure factor of an S=1 Heisenberg chain, showing the bulk spin gap and the fractionalized zero-energy edge modes.

Qutranpy

Quantum transport in a two-terminal geometry, with the Landauer and scattering matrix formalism. The Hamiltonians of the leads and of the scattering region can each be given exchange fields, a mass term, spin-orbit coupling or superconductivity. Built on the pygra library.

The Qutranpy window, with the parameters of the left lead, central region and right lead in columns, and sweeps in a Hamiltonian parameter, in energy and in the length of the scattering region.
Qutranpy: the parameters of the two leads and the central region.

Tranci

Electronic properties of transition metal atoms on surfaces, solved in the full many-body space of the d orbitals with the configuration interaction method, including crystal fields, spin-orbit coupling and electronic interactions. The results are written to a PDF: the operators projected onto the ground state manifold, the eigenstates, and how the levels evolve with each parameter.

The Tranci window: a single-shot or sweep calculation on the left, and the general, spin-orbit, crystal field and magnetic field parameters on the right.
Tranci: a single-shot calculation and its parameters.