QURI SDK Architecture

QURI SDK is not a single library but three: QURI Parts, QURI Algo and QURI VM. This page explains why the SDK is shaped this way, how the pieces relate, and which one to reach for.

Why three libraries?

Quantum algorithm research happens at very different levels of abstraction. Some work is about circuits themselves: composing gates, preparing states, measuring operators. Some work is about whole algorithms: time evolution, phase estimation, variational loops. And in the (E)FTQC era, a growing share of the work is about questions like “how many logical qubits and how much runtime would this algorithm need on that architecture?”, questions that must be answered before the hardware exists.

A single library serving all three needs would force every user through every layer. QURI SDK instead separates the concerns:

• QURI Parts is the circuit level. It provides the building blocks (circuits, states, operators, samplers and estimators) with a design goal of hardware independence: the same code runs on simulators and real devices through interchangeable backends.

• QURI Algo is the algorithm level. It defines algorithms platform-independently and ships Early-FTQC algorithms ready to use, so that algorithm-level research does not have to wire circuits by hand.

• QURI VM is the evaluation level. It models quantum architectures and devices, transpiles circuits to error-corrected architectures, and estimates the resources an algorithm would consume: simulation and analysis for hardware that may not be available yet.

The reason for the split is the same as the reason compilers separate front ends from back ends: each layer can evolve independently, and users enter at the level that matches their problem.

How the pieces relate

The layers compose rather than compete. An algorithm assembled with QURI Algo is built out of QURI Parts components, and the result can be handed to QURI VM to evaluate its cost on a chosen architecture. A typical research workflow touches all three: build with Parts, assemble with Algo, evaluate with VM.

Which should I use?

I want to…	Start with
Build and simulate a quantum circuit	QURI Parts
Use a ready-made (Early-FTQC) algorithm	QURI Algo
Estimate resources / evaluate an algorithm on an architecture	QURI VM

If you are unsure, start with QURI Parts: the other two build on its concepts.

Related reading

• Quick Start: install and run your first circuit.

• Define your first qsub circuit: the FTQC-oriented circuit abstraction.

• For quantum chemistry, a suggested reading order: QURI Parts Tutorials → Introduction to Quantum Chemistry → Molecular Orbitals → Hamiltonian Generation.