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Expose apply to allow arbitrary unitary application #208

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Dec 4, 2024
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Expose apply to allow arbitrary unitary application #208

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fa91218
Expose `apply` to allow arbitrary unitary application
swernli Dec 3, 2024
c5e8a4e
Fix fmt
swernli Dec 4, 2024
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111 changes: 110 additions & 1 deletion sparsesim/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,9 +16,10 @@ mod nearly_zero;
mod matrix_testing;

use crate::nearly_zero::NearlyZero;
use ndarray::{s, Array2};
use num_bigint::BigUint;
use num_complex::Complex64;
use num_traits::{One, Zero};
use num_traits::{One, ToPrimitive, Zero};
use rand::{rngs::StdRng, Rng, SeedableRng};
use rustc_hash::{FxHashMap, FxHashSet};
use std::{cell::RefCell, f64::consts::FRAC_1_SQRT_2, fmt::Write};
Expand Down Expand Up @@ -1194,6 +1195,114 @@ impl QuantumSim {

self.mcrotation(ctls, theta, target, true);
}

/// Applies the given unitary to the given targets, extending the unitary to accomodate controls if any.
/// # Panics
///
/// This function will panic if given ids in either targets or optional controls that do not correspond to allocated
/// qubits, or if there is a duplicate id in targets or controls.
/// This funciton will panic if the given unitary matrix does not match the number of targets provided.
/// This function will panic if the given unitary is not square.
/// This function will panic if the total number of targets and controls too large for a `u32`.
pub fn apply(
&mut self,
unitary: &Array2<Complex64>,
targets: &[usize],
controls: Option<&[usize]>,
) {
let mut targets = targets.to_vec();
let mut unitary = unitary.clone();

assert!(
unitary.ncols() == unitary.nrows(),
"Application given non-square matrix."
);

assert!(
targets.len() == unitary.ncols() / 2,
"Application given incorrect number of targets; expected {}, given {}.",
unitary.ncols() / 2,
targets.len()
);

if let Some(ctrls) = controls {
// Add controls in order as targets.
ctrls
.iter()
.enumerate()
.for_each(|(index, &element)| targets.insert(index, element));

// Extend the provided unitary by inserting it into an identity matrix.
unitary = controlled(&unitary, ctrls.len().try_into().unwrap());
}
Self::check_for_duplicates(&targets);

self.flush_queue(&targets, FlushLevel::HRxRy);

targets
.iter()
.rev()
.enumerate()
.for_each(|(target_loc, target)| {
let loc = *self
.id_map
.get(target)
.unwrap_or_else(|| panic!("Unable to find qubit with id {target}"));
let swap_id = *self
.id_map
.iter()
.find(|(_, &value)| value == target_loc)
.unwrap()
.0;
self.swap_qubit_state(loc, target_loc);
*(self.id_map.get_mut(&swap_id).unwrap()) = loc;
*(self.id_map.get_mut(target).unwrap()) = target_loc;
});

let op_size = unitary.nrows();
self.state = self
.state
.drain()
.fold(SparseState::default(), |mut accum, (index, val)| {
let i = &index / op_size;
let l = (&index % op_size)
.to_usize()
.expect("Cannot operate on more than 64 qubits at a time.");
for j in (0..op_size).filter(|j| !unitary.row(*j)[l].is_nearly_zero()) {
let loc = (&i * op_size) + j;
if let Some(entry) = accum.get_mut(&loc) {
*entry += unitary.row(j)[l] * val;
} else {
accum.insert((&i * op_size) + j, unitary.row(j)[l] * val);
}
if accum
.get(&loc)
.map_or_else(|| false, |entry| (*entry).is_nearly_zero())
{
accum.remove(&loc);
}
}
accum
});
assert!(
!self.state.is_empty(),
"State vector should never be empty."
);
}
}

/// Extends the given unitary matrix into a matrix corresponding to the same unitary with a given number of controls
/// by inserting it into an identity matrix.
#[must_use]
pub fn controlled(u: &Array2<Complex64>, num_ctrls: u32) -> Array2<Complex64> {
let mut controlled_u = Array2::eye(u.nrows() * 2_usize.pow(num_ctrls));
controlled_u
.slice_mut(s![
(controlled_u.nrows() - u.nrows())..,
(controlled_u.ncols() - u.ncols())..
])
.assign(u);
controlled_u
}

#[cfg(test)]
Expand Down
117 changes: 4 additions & 113 deletions sparsesim/src/matrix_testing.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,109 +2,12 @@
// Licensed under the MIT License.

use core::f64::consts::FRAC_1_SQRT_2;
use ndarray::{array, s, Array2};
use ndarray::{array, Array2};
use num_complex::Complex64;
use num_traits::One;
use num_traits::ToPrimitive;
use num_traits::Zero;

use crate::{nearly_zero::NearlyZero, FlushLevel, QuantumSim, SparseState};

impl QuantumSim {
/// Applies the given unitary to the given targets, extending the unitary to accomodate controls if any.
/// # Panics
///
/// This function will panic if given ids in either targets or optional controls that do not correspond to allocated
/// qubits, or if there is a duplicate id in targets or controls.
/// This funciton will panic if the given unitary matrix does not match the number of targets provided.
/// This function will panic if the given unitary is not square.
/// This function will panic if the total number of targets and controls too large for a `u32`.
pub(crate) fn apply(
&mut self,
unitary: &Array2<Complex64>,
targets: &[usize],
controls: Option<&[usize]>,
) {
let mut targets = targets.to_vec();
let mut unitary = unitary.clone();

assert!(
unitary.ncols() == unitary.nrows(),
"Application given non-square matrix."
);

assert!(
targets.len() == unitary.ncols() / 2,
"Application given incorrect number of targets; expected {}, given {}.",
unitary.ncols() / 2,
targets.len()
);

if let Some(ctrls) = controls {
// Add controls in order as targets.
ctrls
.iter()
.enumerate()
.for_each(|(index, &element)| targets.insert(index, element));

// Extend the provided unitary by inserting it into an identity matrix.
unitary = controlled(&unitary, ctrls.len().try_into().unwrap());
}
Self::check_for_duplicates(&targets);

self.flush_queue(&targets, FlushLevel::HRxRy);

targets
.iter()
.rev()
.enumerate()
.for_each(|(target_loc, target)| {
let loc = *self
.id_map
.get(target)
.unwrap_or_else(|| panic!("Unable to find qubit with id {target}"));
let swap_id = *self
.id_map
.iter()
.find(|(_, &value)| value == target_loc)
.unwrap()
.0;
self.swap_qubit_state(loc, target_loc);
*(self.id_map.get_mut(&swap_id).unwrap()) = loc;
*(self.id_map.get_mut(target).unwrap()) = target_loc;
});

let op_size = unitary.nrows();
self.state = self
.state
.drain()
.fold(SparseState::default(), |mut accum, (index, val)| {
let i = &index / op_size;
let l = (&index % op_size)
.to_usize()
.expect("Cannot operate on more than 64 qubits at a time.");
for j in (0..op_size).filter(|j| !unitary.row(*j)[l].is_nearly_zero()) {
let loc = (&i * op_size) + j;
if let Some(entry) = accum.get_mut(&loc) {
*entry += unitary.row(j)[l] * val;
} else {
accum.insert((&i * op_size) + j, unitary.row(j)[l] * val);
}
if accum
.get(&loc)
.map_or_else(|| false, |entry| (*entry).is_nearly_zero())
{
accum.remove(&loc);
}
}
accum
});
assert!(
!self.state.is_empty(),
"State vector should never be empty."
);
}
}
use crate::{nearly_zero::NearlyZero, QuantumSim};

/// Returns a unitary matrix representing the `X` operation.
#[must_use]
Expand Down Expand Up @@ -255,21 +158,9 @@ pub fn adjoint(u: &Array2<Complex64>) -> Array2<Complex64> {
u.t().map(Complex64::conj)
}

/// Extends the given unitary matrix into a matrix corresponding to the same unitary with a given number of controls
/// by inserting it into an identity matrix.
#[must_use]
pub fn controlled(u: &Array2<Complex64>, num_ctrls: u32) -> Array2<Complex64> {
let mut controlled_u = Array2::eye(u.nrows() * 2_usize.pow(num_ctrls));
controlled_u
.slice_mut(s![
(controlled_u.nrows() - u.nrows())..,
(controlled_u.ncols() - u.ncols())..
])
.assign(u);
controlled_u
}

mod tests {
use crate::controlled;

use super::*;
use core::f64::consts::PI;

Expand Down
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