방사광 X선 극저온 나노프로브 반도체 양자점 단일 광자 비구별성(Indistinguishability) HOM 간섭 서보 C# SIMD 엔진

3. Zero-Allocation C# SIMD 양자점 단일 광자 HOM 서보 엔진

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

namespace ZeliDesk.Stem.Synchrotron.QuantumDotHom
{
    public readonly ref struct HomInterferenceState
    {
        public readonly float HomVisibilityPct;
        public readonly float SpectralWavelengthJitterPm;
        public readonly float StarkGateVoltage;
        public readonly bool IndistinguishabilityLocked;

        public HomInterferenceState(float vis, float jitter, float volt, bool locked)
        {
            HomVisibilityPct = vis;
            SpectralWavelengthJitterPm = jitter;
            StarkGateVoltage = volt;
            IndistinguishabilityLocked = locked;
        }
    }

    public sealed class QuantumDotHomServoEngine
    {
        private const float SampleRateHz = 100000.0f;
        private const float Dt = 1.0f / SampleRateHz;

        // 목표 가시도 (98.0% 이상 유지)
        private const float TargetVisibilityPct = 98.0f;
        private const float CenterWavelengthNm = 920.0f;

        // PI 서보 제어 상태
        private float _wavelengthIntegral = 0.0f;
        private float _prevError = 0.0f;
        private const float KpGate = 0.45f;
        private const float KiGate = 65.0f;

        [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
        public HomInterferenceState LockIndistinguishability(
            float measuredWavelengthNm,
            float coincidenceCountsAtZeroDelay,
            float coincidenceCountsAtInfinity,
            float cryogenicTempK)
        {
            // 1. HOM 양자 간섭 가시도(%) 계산: V = (C_inf - C_0) / C_inf * 100
            float safeInf = MathF.Max(coincidenceCountsAtInfinity, 1.0f);
            float homVisibility = Math.Clamp(((safeInf - coincidenceCountsAtZeroDelay) / safeInf) * 100.0f, 0.0f, 100.0f);

            // 2. 기준 중심 파장 대비 지터 오차(Picometer 단위)
            float wavelengthErrorPm = (measuredWavelengthNm - CenterWavelengthNm) * 1000.0f;

            // 3. 적분 연산 및 윈드업 방지
            _wavelengthIntegral += wavelengthErrorPm * Dt;
            _wavelengthIntegral = Math.Clamp(_wavelengthIntegral, -0.5f, 0.5f);

            // 온도 상승에 따른 포논 디페이징 피드포워드 보정 (T^3 의존성)
            float phononDecoherence = MathF.Pow(MathF.Max(cryogenicTempK, 4.0f) / 4.0f, 3.0f) * 0.05f;

            float gateControlSignal = (KpGate * wavelengthErrorPm) + (KiGate * _wavelengthIntegral) + phononDecoherence;
            float finalGateVoltage = Math.Clamp(1.5f - gateControlSignal, 0.0f, 5.0f);

            bool isLocked = homVisibility >= TargetVisibilityPct && MathF.Abs(wavelengthErrorPm) < 0.5f;

            return new HomInterferenceState(
                vis: homVisibility,
                jitter: wavelengthErrorPm,
                volt: finalGateVoltage,
                locked: isLocked
            );
        }
    }
}