nativ3 0.1.0

Topology-aware quantum circuit compiler with relay-bit fault isolation

Nativ3

Topology-aware quantum circuit compiler with fault isolation analysis.

Nativ3 treats circuit topology as the primitive, not the gate. It classifies every qubit by its role in the directed gate graph and provides exact fault isolation guarantees based on a single binary property: the relay bit.

The Relay-Bit Principle

A qubit propagates errors if and only if it serves as a CNOT control after serving as a target.

r(q) = 1  →  relay (target then control)  →  propagates errors
r(q) = 0  →  hub or spoke                 →  fault-isolated

Install

pip install -e .                    # core (analysis only, no Qiskit needed)
pip install -e ".[qiskit]"          # with Qiskit circuit generation

Usage

Python API

from nativ3 import star, chain, dual_hub, compile

# Star topology — all spokes fault-isolated
result = compile(star(hub=0, spokes=[1, 2, 3]))
print(result.report())

# Chain topology — WARNING: has relay qubits
result = compile(chain([0, 1, 2, 3]))
print(result.report())
# ⚠ q1 is a RELAY (target at t=0, control at t=1)
# ⚠ q2 is a RELAY (target at t=1, control at t=2)

# Dual-hub — total fault isolation, no relays anywhere
result = compile(dual_hub(hubs=[0, 4], spokes=[1, 2, 3]))
print(result.report())
# ✓ fully fault-isolated

# Tradeoff analysis
from nativ3 import analyze_tradeoff
tradeoff = analyze_tradeoff(chain([0, 1, 2, 3]), alpha=0.3)
print(tradeoff['recommendation'])

Command Line

nativ3 star 0 1,2,3                    # star with hub=q0
nativ3 chain 0,1,2,3                   # chain (shows relay warnings)
nativ3 dual_hub 0,4 1,2,3              # dual-hub (total isolation)
nativ3 tradeoff 0,1,2,3 --alpha 0.5    # chain→star cost analysis
nativ3 compare 0,1,2                   # compare star vs chain states

Three Theorems

Based on the paper: DOI 10.5281/zenodo.19210676

1. Non-transitivity: Star ≠ chain for non-trivial middleman states
2. Fidelity formula: F(star, chain) = cos⁴(α), independent of opening gate
3. Fault isolation: Star topologies exactly preserve hub-endpoint correlations under arbitrary TPCP noise on spoke qubits

Node Types

Type	Role	Relay Bit	Fault Behavior
Hub (H)	Control-only	0	Errors propagate TO targets
Spoke (S)	Target-only	0	Errors stay local — isolated
Relay (R)	Target→Control	1	Errors propagate downstream

License

MIT