qoqo

qoqo is a toolkit to represent quantum circuits by HQS Quantum Simulations. The name “qoqo” stands for “Quantum Operation Quantum Operation,” making use of reduplication.

For a detailed introduction see the user documentation and the qoqo examples repository. Additionally, the API documentation is available.

What qoqo is:

• A toolkit to represent quantum programs including circuits and measurement information.

• A thin runtime to run quantum measurements.

• A way to serialize quantum circuits and measurement information.

• A set of optional interfaces to devices, simulators and toolkits (e.g. qoqo_quest, qoqo_qiskit, qoqo_for_braket, qoqo_iqm).

What qoqo is not:

• A decomposer translating circuits to a specific set of gates
• A quantum circuit optimizer
• A collection of quantum algorithms

If you are looking for a comprehensive package that integrates all these features, we invite you to explore our HQStage software.

This repository contains two components:

• qoqo: the python interface to roqoqo, described here.

• roqoqo: the core rust library. Further details are provided in the individual README file here.

Installation

On Linux, macOS and Windows on x86 precompiled packages can be found on PyPi and installed via

pip install qoqo

If no pre-built python wheel is available for your architecture, you can install qoqo from the source distribution using a rust toolchain as described here.

Create your first circuit in qoqo

The following code snippet can be used to create your first circuit in qoqo. For an expanded collection of examples please see the jupyter notebooks in the qoqo_examples repository.

from qoqo import Circuit
from qoqo import operations as ops
from qoqo_quest import Backend

circuit = Circuit()
circuit += ops.DefinitionBit(name="classical_reg", length=2, is_output=True)
circuit += ops.PauliX(qubit=0)
circuit += ops.CNOT(0,1)
circuit += ops.PragmaDamping(qubit=0, gate_time=0.1, rate=0.1)
circuit += ops.PragmaDamping(qubit=1, gate_time=0.1, rate=0.1)
circuit += ops.MeasureQubit(qubit=0, readout="classical_reg", readout_index=0)
circuit += ops.MeasureQubit(qubit=1, readout="classical_reg", readout_index=1)
circuit += ops.PragmaSetNumberOfMeasurements(number_measurements=1000, readout="classical_reg")

backend = Backend(number_qubits=2)
bit_registers, float_registers, complex_registers = backend.run_circuit(circuit)

Features

qoqo provides the following functionalities and features:

• A Circuit class to represent quantum circuits
• A QuantumProgram class to represent quantum programs
• Classes representing single-qubit, two-qubit, multi-qubit and measurement operations that can be executed (decomposed) on any universal quantum computer
• Classes representing so-called PRAGMA operations that only apply to certain hardware, simulators or annotate circuits with additional information
• Support for symbolic variables
• Readout based on classical registers
• Measurement classes for evaluating observable measurements based on raw readout date returned by quantum computer backends
• Serialization to json and deserialization from json for circuits and measurement information. Serialization support can easily be expanded to other targets with the help of the serde crate.

Support

This project has been partly supported by PlanQK and is partially supported by QSolid and PhoQuant.

Contribution

We welcome contributions to the project. If you want to contribute code, please have a look at CONTRIBUTE.md for our code contribution guidelines.

In order to facilitate the contribution of the addition of a new gate, please also have a look at add_new_gate.md to read a quick explanation of the main steps necessary.

Citation

If you use qoqo, please cite it by including the URL of this github repository, or using the provided BibTeX entry:

@misc{qoqo2021,
      title={qoqo - toolkit to represent quantum circuits},
      author={HQS Quantum Simulations GmbH},
      year={2021},
      url={https://github.com/HQSquantumsimulations/qoqo},
}