README.md

QuantumGoose

An OCaml library for quantum computing

Requirements

The library has been tested to work with OCaml version 4.14.0.

OCaml/opam can be installed from the OCaml website.

Additionally, to compile the library, we rely on the following packages: opal, dune, and ppx_inline_test.

They can be installed using opam.

Install

Clone the repository, then...

cd Goose
opam install dune opal ppx_inline_test

Afterwards, the library can be compiled using

dune build

To run the library test suite:

dune runtest

Examples

Building a Quantum Circuit in the Goose IR

The following is a quantum circuit that computes GHZ states. This entangles the qubits such that when one is measured, the states of the others are immediately determined.

The following OCaml code generates an n-qubit entanglement circuit, which computes GHZ states.

let entanglement n = {
  qbits = n;
  gates = List.cons ({
    target = A 0;
    kind = H;
    controls = []
  }) (List.init (n - 1) (fun i -> {
    target = A (i + 1);
    kind = X;
    controls = [A 0]
  }))
}

C code emission

The above entanglement circuit can be compiled to C using the symbolic simulator:

open Quantumlib
open C_emitter

emitc (entanglement 3) (open_out "se_c_bin/ent3.c")

This produces the following C code for a 3-qubit entanglement circuit:

int main(int argc, char **argv) {
    cfloat *state = (cfloat *) malloc(N * sizeof(cfloat));

    // Initialize state
    for (int i = 0; i < N; i++) {
        state[i] = (cfloat) {0.0, 0.0};
    }
    state[0] = (cfloat) {1.0, 0.0};

    // Allocate output state buffer
    cfloat *out_state = (cfloat *) malloc(N * sizeof(cfloat));

    out_state[0] = cmul(SQRT1_2,cadd(state[0],state[1]));
    out_state[1] = cmul(SQRT1_2,csub(state[6],state[7]));
    out_state[2] = cmul(SQRT1_2,cadd(state[2],state[3]));
    out_state[3] = cmul(SQRT1_2,csub(state[4],state[5]));
    out_state[4] = cmul(SQRT1_2,cadd(state[4],state[5]));
    out_state[5] = cmul(SQRT1_2,csub(state[2],state[3]));
    out_state[6] = cmul(SQRT1_2,cadd(state[6],state[7]));
    out_state[7] = cmul(SQRT1_2,csub(state[0],state[1]));


    // Print state
    for (int i = 0; i < N; i++) {
        printf("|%d>: %f + %fi\n", i, out_state[i].real, out_state[i].imag);
    }

    return 0;
}