spinachlang-algorithms

Popular quantum algorithms implemented in Spinach, covering everything from basic primitives to a full error-correction protocol.

Algorithms

File	Algorithm	Qubits	Key features
superposition.sph	Single-qubit superposition	1	H gate, measurement
entanglement.sph	Bell pair (entanglement)	2	H, FCX, wildcard *
interference.sph	Quantum interference	1	H, Z, H cancellation
deutsch.sph	Deutsch's algorithm	2	Phase kickback, oracle
deutsch_jozsa.sph	Deutsch-Jozsa (n=2)	3	Named instructions, H|FCX|H pipeline
bernstein_vazirani.sph	Bernstein-Vazirani (s=101)	4	Named instructions, oracle
grover.sph	Grover's search (2-qubit, target |11⟩)	2	Named instruction, reverse pipeline <-, CZ
half_adder.sph	Quantum half-adder	3	CCX (Toffoli), CX
qft.sph	Quantum Fourier Transform (3-qubit)	3	CU1 rotation gates, SWAP
phase_estimation.sph	Quantum Phase Estimation (1-bit)	2	Pipeline: H|CZ|H|M
swap_test.sph	Swap test (state fidelity)	3	CSWAP (Fredkin), H sandwich
teleportation.sph	Quantum teleportation	3	FCX, list measurement, if conditionals
superdense_coding.sph	Superdense coding ("11")	2	Long pipeline, Z|X encoding
ghz.sph	GHZ state	3	H, cascaded FCX
qec_bit_flip.sph	3-Qubit Bit-Flip QEC ★	5+ancilla	See below

Spotlight: qec_bit_flip.sph

The largest algorithm in the collection — a complete quantum error correction protocol that exercises every major Spinach feature in one program:

# Named instructions — encode, synmeas0, synmeas1
encode   : FCX(rep1) | FCX(rep2)
synmeas0 : CX(data) | CX(rep1)

# Reverse pipeline — adjoint of encode
data -> encode <-

# Classical bit logic — NOT / AND / OR
nots0  -> NOT(syn0)
corr1  -> AND(syn0, syn1)
anyerr -> OR(syn0, syn1)

# Conditional (if) — feedforward correction
rep1 -> X if corr1

# Conditional (if-else) — diagnostic phase tag
data -> S if anyerr else T

# List target + wildcard
[anc0, anc1] -> M
* -> BARRIER

The nine-stage protocol:

1. Prepare logical |+⟩ on data
2. Encode into 3-qubit repetition code via data -> encode
3. Inject a bit-flip error (rep1 -> X) to simulate noise
4. Syndrome measurement — two ancilla qubits reveal which qubit flipped
5. Classical decode — NOT/AND/OR bit arithmetic identifies the error
6. Feedforward correction — conditional X restores the damaged qubit
7. Diagnostic — if-else tags the execution path with a phase gate
8. Decode — data -> encode <- (reverse pipeline) uncomputes the encoding
9. Measure all — * -> M reads out the final state

QASM note: the classical bit operations in stages 5-7 exceed QASM 2.0. The .qasm companion captures stages 1-4 only. For the full corrected circuit:

spinachlang -l json qec_bit_flip.sph

Running the examples

# Compile any algorithm to QASM
spinachlang -l qasm spinachlang-algorithms/grover.sph

# Use JSON for circuits with classical post-processing
spinachlang -l json spinachlang-algorithms/qec_bit_flip.sph

# Pipe to stdout
cat spinachlang-algorithms/superposition.sph | spinachlang -l qasm -