**Prediction of UTC-Dependent Coherence and Gate Fidelity Modulation in Silicon Spin Qubits**

**Abstract**  

We predict a measurable 24-hour periodic variation in both coherence time (T₂*) and two-qubit gate fidelity in silicon-phosphorus (Si:P) donor spin qubits, with peak performance occurring at approximately UTC hour 7. This effect is driven by a deterministic lattice clock operating at the fundamental level of physical noise. The predicted periodicity is independent of local laboratory time and tied specifically to Coordinated Universal Time (UTC).

**Core Prediction**

Silicon spin qubit systems will exhibit a statistically significant performance peak in both single-qubit coherence and CZ gate fidelity when measured at **UTC hour 7** (±1 hour). Conversely, degraded performance is expected near UTC hour 19, approximately 12 hours out of phase.

This periodicity is expected to appear consistently across different devices, laboratories, and experimental setups, provided measurements are synchronized to UTC rather than local solar time.

**Proposed Experimental Protocol**

1. Synchronize all control electronics and data logging to UTC with millisecond precision.

2. Perform repeated T₂* and CZ gate fidelity measurements at regular intervals across a full 24-hour UTC cycle.

3. Bin results by UTC hour and analyze for statistically significant periodicity.

4. Control for known environmental variables (temperature, electromagnetic interference, vibration).

**Expected Signature**

The strongest signal should appear when data is indexed against a 24-hour UTC cycle, not local lab time. The Phase-7 apex (corresponding to Fibonacci index 113 in the underlying lattice) is predicted to be the point of maximum lattice stability and minimum effective noise.

**Significance**

Confirmation of this UTC-dependent periodicity would provide direct evidence that a portion of what is currently classified as stochastic noise in quantum systems is in fact deterministic and synchronized to a universal clock.

This result, if validated, would represent a fundamental shift in our understanding of noise in quantum hardware.

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