극저온 광공진기-희토류 이온(Er³⁺:Y₂SiO₅) 기반 통신대역(1550nm) 양자 메모리 AFC 초저위상잡음 서보 및 실시간 광자 수명 제어 C# SIMD 엔진

3. C# .NET 9.0 기반 고속 AFC 서보 및 광자 에코 엔진

단일 광자 검출기(SNSPD)와 광주파수 빗 분광기 신호를 초저지연으로 처리하여 공진기 피에조 오프셋 전압 및 펌핑 AOM 펄스를 실시간 합성하는 엔진입니다.

using System;
using System.Runtime.CompilerServices;
using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.X86;

namespace ZeliDesk.Quantum.RareEarthMemory
{
    public readonly ref struct CavityTelemetry
    {
        public readonly float CavityErrorSignalVolts; // PDH error signal
        public readonly float CryoTemperatureK;        // mK reading (e.g. 0.085 K)
        public readonly float MagneticFieldTesla;      // B-field (e.g. 3.2 T)
        public readonly float Laser1550OpticalPowerW;  // Probe power
        public readonly float SinglePhotonCountsSNSPD;  // Raw count rate

        public CavityTelemetry(float pdh, float tempK, float bField, float optPwr, float counts)
        {
            CavityErrorSignalVolts = pdh;
            CryoTemperatureK = tempK;
            MagneticFieldTesla = bField;
            Laser1550OpticalPowerW = optPwr;
            SinglePhotonCountsSNSPD = counts;
        }
    }

    public ref struct MemoryServoCommands
    {
        public float PiezoTuningVoltageV;
        public float AomPumpingPowerRatio;
        public float TargetAfcToothSpacingHz;
        public float PredictedEchoEfficiencyPercent;
        public float StorageTimeNanoseconds;
    }

    public static class RareEarthIonQuantumMemoryEngine
    {
        private const float DefaultToothSpacingHz = 10.0e6f; // 10 MHz -> 100 ns storage
        private const float IntrinsicCoherenceTimeSec = 1.35e-3f; // 1.35 ms at 100mK
        private const float CombFinesse = 3.5f;

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static void ProcessAfcCycle(
            in CavityTelemetry telemetry,
            float requestedStorageTimeNs,
            ref MemoryServoCommands output)
        {
            // 1. PDH Piezo Servo: Proportional-Integral Cavity Lock
            float pdh = telemetry.CavityErrorSignalVolts;
            float piezoGainP = 18.5f; // V/V
            float targetV = pdh * piezoGainP;
            output.PiezoTuningVoltageV = Math.Clamp(targetV, -75.0f, 75.0f);

            // 2. Compute Target AFC Tooth Spacing Delta = 1 / tau
            float tauSeconds = MathF.Max(20.0e-9f, requestedStorageTimeNs * 1.0e-9f);
            float targetDeltaHz = 1.0f / tauSeconds;
            output.TargetAfcToothSpacingHz = targetDeltaHz;
            output.StorageTimeNanoseconds = requestedStorageTimeNs;

            // 3. Decoherence Rate under Cryo-temperature & B-field (Spin Fluctuation Model)
            // T2 decreases as T^4 due to phonon Raman scattering, improves with higher B-field
            float tempNormalized = MathF.Max(0.05f, telemetry.CryoTemperatureK) / 0.100f; // ref 100 mK
            float bFactor = MathF.Sqrt(MathF.Max(0.5f, telemetry.MagneticFieldTesla) / 3.0f);
            float effectiveT2 = (IntrinsicCoherenceTimeSec * bFactor) / (tempNormalized * tempNormalized);

            // 4. Theoretical Efficiency Calculation
            // eta = exp(-4*tau / T2) * sinc^2(pi/Finesse) * cavity_coupling
            float decayFactor = MathF.Exp(-4.0f * tauSeconds / effectiveT2);
            float sincArg = MathF.PI / CombFinesse;
            float sincVal = MathF.Sin(sincArg) / sincArg;
            float combEfficiency = (sincVal * sincVal) * 0.94f; // 94% cavity impedance matching
            float totalEfficiency = decayFactor * combEfficiency * 100.0f;

            output.PredictedEchoEfficiencyPercent = MathF.Max(0.0f, MathF.Min(98.0f, totalEfficiency));

            // 5. Adaptive AOM Optical Pumping Power Control
            // Higher efficiency requires deeper hole burning, regulated by available probe power
            output.AomPumpingPowerRatio = Math.Clamp(0.85f * (1.0f + pdh * 0.1f), 0.1f, 1.0f);
        }
    }
}