Tequila

Tequila is an Extensible Quantum Information and Learning Architecture where the main goal is to simplify and accelerate implementation of new ideas for quantum algorithms. It operates on abstract data structures allowing the formulation, combination, automatic differentiation and optimization of generalized objectives. Tequila can execute the underlying quantum expectation values on state of the art simulators as well as on real quantum devices.

You can get an overview from this presentation

Get started with our Tutorials

Quantum Backends

Currently supported

Tequila detects backends automatically if they are installed on your systems.
All of them are available over standard pip installation like for example pip install qulacs.
For best performance tt is recommended to have qulacs installed.

QuantumChemistry:

Tequila supports Psi4.
In a conda environment this can be installed with
conda install psi4 -c psi4

Installation

We recommend installing in editable mode with
git clone https://github.com/aspuru-guzik-group/tequila.git
cd tequila
pip install -e .

Do not install over PyPi (Minecraft lovers excluded)
~~pip install tequila~~

Recommended Python version is 3.7 or 3.6

Getting Started

Check out the tutorial notebooks provided in tutorials.

Tequila Hello World

# optimize a one qubit example

# define a variable
a = tq.Variable("a")
# define a simple circuit
U = tq.gates.Ry(angle=a*pi, target=0)
# define an Hamiltonian
H = tq.paulis.X(0)
# define an expectation value
E = tq.ExpectationValue(H=H, U=U)
# optimize the expectation value
result = tq.minimize(method="bfgs", objective=E**2)
# check out the optimized wavefunction
wfn = tq.simulate(U, variables=result.angles)
print("optimized wavefunction = ", wfn)
# plot information about the optimization
result.history.plot("energies")
result.history.plot("angles")
result.history.plot("gradients")

Chemistry Hello World

# define a molecule within an active space
active = {"a1": [1], "b1":[0]}
molecule = tq.quantumchemistry.Molecule(geometry="lih.xyz", basis_set='6-31g', active_orbitals=active, transformation="bravyi-kitaev")

# get the qubit hamiltonian
H = molecule.make_hamiltonian()

# make the UCCSD ansatz with cc2 ordering
U = molecule.make_uccsd_ansatz(initial_amplitudes="cc2", trotter_steps=1)

# define the expectationvalue
E = tq.ExpectationValue(H=H, U=U)

# compute reference energies
fci = molecule.compute_energy("fci")
cisd = molecule.compute_energy("detci", options={"detci__ex_level": 2})

# optimize
result = tq.minimize(objective=E, method="BFGS", gradient="2-point", method_options={"eps":1.e-3}, initial_values={k:0.0 for k in E.extract_variables()})

print("VQE : {:+2.8}f".format(result.energy))
print("CISD: {:+2.8}f".format(cisd))
print("FCI : {:+2.8}f".format(fci))

Dependencies

Support for additional optimizers can be activated by intalling them in your environment.
Tequila will then detect them automatically.
Currently those are: Phoenics and GPyOpt.

Documentation

You can build the documentation by navigating to docs and entering make html.
Open the documentation with a browser over like firefox docs/build/html/index.html

Troubleshooting

If you experience trouble of any kind or if you either want to implement a new feature or want us to implement a new feature that you need:
don't hesitate to contact us directly or raise an issue here on github

You will need cmake to install the qulacs simulator
pip install cmake
You don't need qulacs for tequila to run (although is is recommended)
To install without qulacs just remove the qulacs line from requirements.txt
It can be replaced by one (or many) of the other supported simulators.
Note that simulators can also be installed on a later point, they don't need to be installed with tequila.
As long as they are installed within the same python environment tequila can detect them.

Windows

You can in principle use tequila with windows as OS and have almost full functionality.
You will need to replace Jax with autograd for it to work.
In order to do so: Remove jax and jaxlib from setup.py and requirements.txt and add autograd instead.

In order to install qulacs you will need latest GNU compilers (at least gcc-7).
They can be installed for example over visual studio.

Mac OS

Tequila runs on Macs OSX.
You might get in trouble with installing qulacs since it currently does not work with Apple's clang compiler.
You need to install latest GNU compile (at least gcc-7 and g++7) and set them as default before installing qulacs over pip.

shukob/tequila