qpz-atomics 1.0.0

Quantum Protocol Zoo Atomic Functions Library

Overview

This library provides atomic functions implementations for easing the development of quantum networking protocols. The library provides functions in a simulation backend agnostic way thanks to a thin wrapping of their basic functionalities. The various atomic function implementations are dispatched in several submodules depending on their anticipated use. The surrent submodules classification is:

• mapping (the thing wrapper around a simulation backend)

• gate (everything that applies a fixed quantum unitary over 1 or 2 qubits)

• prep (operations related to prepare given sets of quantum states)

• meas (operations related to measure quantum subsystems according to some fixed POVM)

• test (operations related to testing that one or several quantum subsystems have a given property)

• util (useful operations that might not be directly related to a specific quantum operation but which are good to have)

• tran (transport layer protocols which might not be readily available for all backends or which would need to include more robust implementations)

Functionality tests are being developed for the atomic functions relying on the hypothesis package. The test tend to follow the cryptographic approach of “correctness”. The “security” part is usually not performed as this most of the times involves checking indistinguishability of probability distributions…

Status

Implemented atomic functions and planning

Name	Implementation	Doc string	Test	Submodule	Comment
Sending qubit (given by simulation backend)	DNE	OK	NA	simulaqron mapping
Receive qubit (given by simulation backend)	DNE	OK	NA	simulaqron mapping
Local Clifford Gates (CNOT, H, Pauli’s)	DNE	OK	NA	simulaqron mapping
Local non-Clifford Gates (T, Tinv)	DNE	OK	NA	simulaqron mapping
CZ gate	DNE	OK	TDO	gate	self inverse, and corresponds to classically controlled Z for comp. basis control
CSWAP gate	DNE	OK	TDO	gate
Creation Pauli eigenstates	DNE	OK	DNE	prep
Creation and broadcast of n-party GHZ state	DNE	OK	DNE	prep
Single qubit equatorial plane preparation	DNE	OK	TDO	prep
Creation and broadcast of n-party stabilizer states	NXT			prep
QFactory	LTR			prep
Projections onto Pauli eigenstates	DNE	OK	OK	meas
Single qubit equatorial plane measurement	TDO			meas
Multi qubit POVM	LTR			meas
Quantum One-Time-Pad encode / decode	DNE	OK	OK	pres
BB84 encode / decode is a subset of QOTP encode / decode	NA	NA	NA	NA
Collective BB84 encoding	DNG			pres
Swap Test	DNE	OK	TDO	test
Verification of stabilizer state				test
Quantum RNG	DNE	Check	TDO	util
Information reconciliation	LTR			util
Classical error correction	LTR			util
Quantum error correction	LTR			util
Privacy amplification	LTR			util
Quantum one-way function	NXT			util
Weak string erasure	NXT
Teleportation send	TDO			tran
Teleportation receive	TDO			tran
Quantum authenticated channel	LTR
Secure classical broadcast channel	LTR
Classical authenticated channel	LTR

Design principles

There exist many different quantum computing backends. The idea with this library was to abstract them away so that code running written using the library could be run on other backends, provided that the rest of the code not composed of functions defined by the library is not backend specific.

To do this, we instantiate the library by giving it a mapping and a node. The mapping is the translation of the backend specific way of calling elementary quantum operations, while the node is the actual quantum registers that are available to perform the computation. The node usually contains also some additional functions such as sending qubits to other nodes, receiving and sending entanglement etc. The differences have been abstracted away with the mappings for simulaqron and qunetsim . Other mappings have been considered and used but not yet made available most notably for Netsquid.

Feel free to add functions, or code new mappings by forking and pull-requesting insertion of your additions. Please keep us updated with your work so that we inform you of changes that could be breaking things.

Usage

Look at the examples/examples.py file. The library is instantiated for each node (as if the nodes were independent computers, each loading its version of the library).

Other sources of inspirations are the tests defined in the tests directory

New atomic functions will be added following the list established by extracting atomic functions from the Quantum Protocol Zoo.

Testing

Tests can be run using python setup.py test at the root of the repository.

The repository includes a tests directory that contains the file test_qpz_atomics.py which gathers all the tests implemented. It is using the pytest package to launch the tests and gather statistics, while being based on hypothesis for generating examples.

For the tests to run, you need to have a quatum network simulator available and running. We have chosen to implement the tests using simulaqron as a backend, hence requiring a running simulaqron instance. This can be done typing the following:

simulaqron set max-qubits 100
simulaqron start

Other backends could be used provided the tests are rewritten and the required backend is available and properly mapped in the library.

Acknowledgments

This project is part of Laboratoire d’Informatique Paris 6 - Sorbonne Université / CNRS - Quantum Information Team. It is funded and is part of the Quantum Internet Alliance European Project.