Written in LUV, runs on light

luv 0.2
target SOLAR sim
field prime 11

let msg ← [3 1 4 1 5 9 2 6]
let cw  ← rs_encode msg
let back ← rs_decode cw          # syndrome check lands in rs_ok["back"]

gate F_d 10
shot seed 3
measure m0

Line-by-line:

field prime 11 — SOLAR is the only chip that uses a prime field instead of a power-of-2 field. The keyword prime tells the compiler to use GF(11) (integers mod 11) instead of GF(2^k). The number 11 is the prime modulus. SOLAR's 10-tooth frequency comb has 10 bins numbered 0–9, and the 11th element (0) wraps around — so arithmetic is modular division over 11 values.

let msg ← [3 1 4 1 5 9 2 6] — bind an array of 8 GF(11) symbols (the digits of pi!) to the variable msg. The arrow ← is LUV's assignment operator (APL-style). Each number must be 0–10 to be valid in GF(11).

rs_encode msg — apply Reed–Solomon encoding to the 8-symbol message, producing a 10-symbol codeword (RS(10,8) adds 2 parity symbols). This is how LUV does quantum error correction — the RS code protects the data across the comb's frequency bins.

rs_decode cw — decode the codeword back, checking for errors. The syndrome result (pass/fail) is stored in rs_ok["back"] — a JSON field the runtime can inspect.

gate F_d 10 — apply the quantum Fourier transform gate (F_d) over dimension 10 (SOLAR's 10 frequency bins). This is a QFP (Quantum Fourier Processor) unitary that rotates the quantum state across all 10 comb teeth simultaneously. The compiler lowers this to a spectral phase mask on SOLAR's AWG.

shot seed 3 — fire one heralded detection event (seed 3 for the random number generator). On SOLAR, this means pumping the 10-tooth comb and detecting which frequency bin clicks.

measure m0 — destructure the SPAD click pattern into a GF(11) symbol stored in variable m0. The detector saw bin #k click → m0 now holds the integer k. This is the measurement result you can branch on.

when m0 = 0 shift 1      # if the click landed in bin 0, advance the grid
when m0 = 5 gate Z_d 10  # if it landed in bin 5, apply a Z_d frame

Line-by-line:

when m0 = 0 shift 1 — this is a conditional feedforward instruction. After measuring, if the result m0 equals 0 (meaning the photon was detected in frequency bin 0), then execute shift 1 — which advances the frequency-bin grid by 1 position. This happens in hardware at the ~11.2 ns feedforward tier: the SPAD fires → TDC timestamps it → FPGA looks up the action in a BRAM table → TFLN electro-optic switch shifts the grid. The photon is held in a delay spiral during this entire ~11 ns loop.

when m0 = 5 gate Z_d 10 — if the measurement result was 5 (bin 5 clicked), apply a Z_d phase gate across all 10 frequency bins. Z_d is the diagonal phase gate in dimension d — it applies a phase rotation of e^(2πi·k/10) to each bin k. This corrects the quantum state based on which detector fired, enabling adaptive error correction in real time.

Each when line compiles to exactly one row in the FPGA's BRAM lookup table. The simulator models the same stall-and-branch semantics — making it the behavioral specification for future firmware.