Hardware Validation — SCPN-Quantum-Control

33/33Jobs Successful

156Qubits Available

176K+Total Shots

20/20Experiments Passed

IBM Heron r2 (ibm_fez)

Hardware Specifications

156 fixed-frequency transmon qubits. Tunable couplers. Median CZ gate error: ~0.3%. T1 ≈ 300 µs. T2 ≈ 200 µs. Heavy-hex connectivity. Accessed via Qiskit Runtime with V2 Estimator and Sampler primitives.

Experiment Results

Experiment	Qubits	CZ Depth	Hardware Result	Exact Value	Relative Error
VQE ground state energy	4	12	−6.2998	−6.3030	0.05%
Kuramoto XY dynamics (1 Trotter rep)	4	85	R = 0.743	R = 0.802	7.3%
Kuramoto XY dynamics (3 Trotter reps)	4	255	R = 0.581	R = 0.802	27.6%
Qubit scaling test	6	147	R = 0.482	R = 0.532	9.3%
UPDE-16 snapshot	16	770	R = 0.332	R = 0.615	46%
Bell inequality (CHSH)	2	3	S = 2.165	S = 2√2	>8σ violation
BB84 QKD protocol	1	2	QBER = 5.5%	<11% threshold	Secure
State preparation fidelity	4	8	F = 0.946	F = 1.0	5.4%

Key Findings

Coherence Wall at Depth 250–400

Clear transition from quantum-dominated to noise-dominated regime. Single Trotter rep (depth 85) maintains 7.3% error; 3 reps (depth 255) degrades to 27.6%. UPDE-16 at depth 770 is fully noise-limited.

Error Mitigation Effectiveness

ZNE with Richardson extrapolation reduces VQE error from 2.1% to 0.05%. Z₂ parity post-selection discards ~15% of shots but improves fidelity by ~8%. Dynamical decoupling extends useful depth by ~20%.

Quantum Entanglement Certified

CHSH S = 2.165 exceeds classical limit 2.0 by >8 standard deviations. Proves genuine quantum correlations in synchronised oscillator states — not simulable classically.

QKD Below Security Threshold

BB84 quantum bit error rate of 5.5% is well below the 11% security threshold. Demonstrates that synchronisation-based quantum states can support cryptographic protocols.

Decoherence Analysis

Error Sources

Gate errors: Median CZ fidelity ~99.7%. Accumulates as 0.3% × N_CZ.
Readout errors: ~1% per qubit. Mitigated by readout error correction matrix.
Crosstalk: Heavy-hex topology minimises but does not eliminate simultaneous-gate crosstalk.
T1 relaxation: Circuit execution time < T1 for shallow circuits. Dominates at depth >400.
T2 dephasing: Phase coherence decays exponentially. Primary limit for phase-sensitive Kuramoto measurements.

Multi-Platform Support

IBM Quantum Production

Full support via qiskit-ibm-runtime. V2 Estimator + Sampler. Automatic transpilation. Error mitigation pipeline. Tested on Heron r2 (156q) and Eagle (127q).

Trapped-Ion Stable

Noise models for trapped-ion hardware. All-to-all connectivity. Higher gate fidelity, lower gate speed. Heating and motional dephasing models.

GPU Simulation Stable

CuPy + JAX backends for GPU-accelerated state vector simulation. Up to 30 qubits on A100. Useful for circuit development before hardware submission.

Circuit Cutting Experimental

Decomposes large circuits into subcircuits executable on smaller devices. Wire cutting and gate cutting. Polynomial overhead in post-processing.