극저온 방사광 X-선 나노회절 기반 플럭소늄(Fluxonium) 초전도 큐비트 비조화성(Anharmonicity) 스위트 스팟 능동 서보 아키텍처 (.NET 9 C# SIMD)

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

namespace ZeliDesk.Quantum.SuperconductingQubits
{
    /// <summary>
    /// 플럭소늄(Fluxonium) 초전도 큐비트 비조화성 스위트 스팟 자속 서보
    /// GC 제로 할당 ref struct 및 AVX-256 SIMD 가속화
    /// </summary>
    public ref struct FluxoniumSweetSpotServo
    {
        private readonly ReadOnlySpan<float> _measuredFluxes;      // 실측 외부 자속 Phi_ext (Phi_0 단위)
        private readonly ReadOnlySpan<float> _anharmonicities;     // 실측 비조화성 alpha (GHz)
        private readonly Span<float> _fluxOffsets;                // 연산된 자속 편차 DeltaPhi
        private readonly Span<float> _coilCurrentCorrections;     // 초전도 코일 전류 보정값 (uA)

        private readonly float _sweetSpotFlux; // 0.5 Phi_0
        private readonly float _fluxGain;      // 자속 제어 게인 (uA/Phi_0)
        private readonly float _currentLimit;  // 최대 허용 보정 전류 (uA)

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public FluxoniumSweetSpotServo(
            ReadOnlySpan<float> measuredFluxes,
            ReadOnlySpan<float> anharmonicities,
            Span<float> fluxOffsets,
            Span<float> coilCurrentCorrections,
            float sweetSpotFlux = 0.5f,
            float fluxGain = 1250.0f,
            float currentLimit = 25.0f)
        {
            _measuredFluxes = measuredFluxes;
            _anharmonicities = anharmonicities;
            _fluxOffsets = fluxOffsets;
            _coilCurrentCorrections = coilCurrentCorrections;
            _sweetSpotFlux = sweetSpotFlux;
            _fluxGain = fluxGain;
            _currentLimit = currentLimit;
        }

        /// <summary>
        /// 8개 플럭소늄 큐비트 채널의 자속 편차를 SIMD 병렬 분석하여 코일 제어 전류 산출
        /// </summary>
        [MethodImpl(MethodImplOptions.AggressiveOptimization)]
        public void ExecuteSweetSpotLock()
        {
            int length = _measuredFluxes.Length;
            int simdLength = length - (length % 8);

            Vector256<float> vSweetSpot = Vector256.Create(_sweetSpotFlux);
            Vector256<float> vGain = Vector256.Create(_fluxGain);
            Vector256<float> vMaxI = Vector256.Create(_currentLimit);
            Vector256<float> vMinI = Vector256.Create(-_currentLimit);

            int i = 0;
            if (Avx2.IsSupported)
            {
                for (; i < simdLength; i += 8)
                {
                    Vector256<float> vFlux = Vector256.Create(MemoryMarshal.Cast<float, Vector256<float>>(_measuredFluxes.Slice(i, 8))[0]);

                    // 자속 편차 DeltaPhi = Phi - SweetSpot
                    Vector256<float> vDeltaPhi = Avx.Subtract(vFlux, vSweetSpot);

                    // 코일 전류 지령 = -Gain * DeltaPhi
                    Vector256<float> vIcoil = Avx.Multiply(Avx.Subtract(Vector256<float>.Zero, vDeltaPhi), vGain);
                    Vector256<float> vClampedI = Avx.Min(vMaxI, Avx.Max(vMinI, vIcoil));

                    vDeltaPhi.CopyTo(_fluxOffsets.Slice(i, 8));
                    vClampedI.CopyTo(_coilCurrentCorrections.Slice(i, 8));
                }
            }

            for (; i < length; i++)
            {
                float deltaPhi = _measuredFluxes[i] - _sweetSpotFlux;
                float icoil = Math.Clamp(-_fluxGain * deltaPhi, -_currentLimit, _currentLimit);
                _fluxOffsets[i] = deltaPhi;
                _coilCurrentCorrections[i] = icoil;
            }
        }
    }
}