Struct QuantumNearestNeighbor 

pub struct QuantumNearestNeighbor { /* private fields */ }

Quantum-Enhanced Nearest Neighbor Search

This structure implements a quantum-inspired nearest neighbor search algorithm that uses quantum state representations and amplitude amplification to enhance search performance. The algorithm can operate in pure quantum mode or fall back to classical computation for compatibility.

Features

• Quantum state encoding of reference points
• Amplitude amplification using Grover-like algorithms
• Quantum fidelity-based distance computation
• Classical fallback for robustness

Example

use scirs2_core::ndarray::Array2;
use scirs2_spatial::quantum_inspired::algorithms::QuantumNearestNeighbor;

let points = Array2::from_shape_vec((3, 2), vec![0.0, 0.0, 1.0, 1.0, 2.0, 2.0]).unwrap();
let mut searcher = QuantumNearestNeighbor::new(&points.view())
    .unwrap()
    .with_quantum_encoding(true)
    .with_amplitude_amplification(true);

let query = scirs2_core::ndarray::arr1(&[0.5, 0.5]);
let (indices, distances) = searcher.query_quantum(&query.view(), 2).unwrap();

Implementations

impl QuantumNearestNeighbor

pub fn new(points: &ArrayView2<'_, f64>) -> SpatialResult<Self>

Create new quantum nearest neighbor searcher

Arguments

• points - Reference points for nearest neighbor search

Returns

A new QuantumNearestNeighbor instance with default configuration

pub fn with_quantum_encoding(self, enabled: bool) -> Self

Enable quantum encoding of reference points

When enabled, reference points are encoded as quantum states which can provide enhanced search performance through quantum parallelism.

Arguments

• enabled - Whether to enable quantum encoding

pub fn with_amplitude_amplification(self, enabled: bool) -> Self

Enable amplitude amplification (Grover-like algorithm)

Amplitude amplification can enhance search performance by amplifying the probability amplitudes of good solutions.

Arguments

• enabled - Whether to enable amplitude amplification

pub fn with_grover_iterations(self, iterations: usize) -> Self

Configure Grover iterations

Sets the number of Grover iterations used in amplitude amplification. More iterations can improve search quality but increase computation time.

Arguments

• iterations - Number of Grover iterations (typically 3-5 for best results)

pub fn query_quantum( &self, query_point: &ArrayView1<'_, f64>, k: usize, ) -> SpatialResult<(Vec<usize>, Vec<f64>)>

Perform quantum-enhanced nearest neighbor search

Finds the k nearest neighbors to a query point using quantum-enhanced distance computation when quantum encoding is enabled, otherwise falls back to classical Euclidean distance.

Arguments

• query_point - Point to search for neighbors
• k - Number of nearest neighbors to find

Returns

Tuple of (indices, distances) for the k nearest neighbors

pub fn len(&self) -> usize

Get number of reference points

pub fn is_empty(&self) -> bool

Check if searcher is empty

pub fn classical_points(&self) -> &Array2<f64>

Get reference to classical points

pub fn is_quantum_enabled(&self) -> bool

Check if quantum encoding is enabled

pub fn is_amplification_enabled(&self) -> bool

Check if amplitude amplification is enabled

Trait Implementations

impl Clone for QuantumNearestNeighbor

fn clone(&self) -> QuantumNearestNeighbor

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for QuantumNearestNeighbor

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.