OpexQuant
Mechanics

How Quantum Works.

Programs are sequences of unitary operations on qubits. Hardware platforms differ wildly. The gates do not.

Example circuit — 3-qubit GHZ preparation

A Hadamard creates superposition on q0. Two CNOTs entangle q1 and q2 with q0, producing the GHZ state (|000⟩ + |111⟩)/√2 — a foundational building block for quantum communication and error correction.

Universal gate set

Quantum gates

H
Hadamard (H)

Creates superposition. Maps |0⟩ → (|0⟩+|1⟩)/√2.

X
Pauli-X

Quantum NOT. Flips |0⟩ ↔ |1⟩.

Z
Pauli-Z

Phase flip on |1⟩. Identity on |0⟩.

⊕
CNOT

Two-qubit entangling gate. Flips target if control = |1⟩.

T
T gate

π/4 phase rotation. Required for universal computation.

⊕⊕
Toffoli (CCX)

Three-qubit gate. Foundational for reversible arithmetic.

Hardware platforms

Where the qubits actually live

IBM Heron R2

Superconducting transmon
156 qubits99.6% 2Q

Tunable couplers, low crosstalk.

Google Willow

Superconducting
105 qubitsBelow threshold d=7

Surface code error scaling demonstrated.

Quantinuum H2

Trapped ion (racetrack)
56 qubits99.85% 2Q

All-to-all connectivity, mid-circuit measurement.

IonQ Forte

Trapped ion
36 algorithmic qubitsAQ #36

Commercial cloud endpoint.

Atom Computing

Neutral atom array
1180+ qubitsMid-99% 2Q

Highly scalable atom counts.

USTC Zuchongzhi-3

Superconducting
105 qubitsComparable to Sycamore

Random circuit sampling benchmarks.