quantrs2_core/
complex_ext.rs

1//! Extended complex number operations for quantum computing
2//!
3//! This module provides enhanced complex number operations by leveraging
4//! SciRS2's type conversion and complex number utilities.
5
6use num_complex::Complex64;
7
8/// Extension trait for Complex64 that adds quantum-specific operations
9pub trait QuantumComplexExt {
10    /// Calculate the probability (squared magnitude) of a quantum amplitude
11    fn probability(&self) -> f64;
12
13    /// Normalize the complex number to have unit magnitude
14    fn normalize(&self) -> Complex64;
15
16    /// Check if two complex numbers are approximately equal within tolerance
17    fn approx_eq(&self, other: &Complex64, tolerance: f64) -> bool;
18
19    /// Calculate the fidelity between two quantum amplitudes
20    fn fidelity(&self, other: &Complex64) -> f64;
21}
22
23impl QuantumComplexExt for Complex64 {
24    fn probability(&self) -> f64 {
25        self.norm_sqr()
26    }
27
28    fn normalize(&self) -> Complex64 {
29        let mag = self.norm();
30        if mag > 0.0 {
31            self / mag
32        } else {
33            Complex64::new(0.0, 0.0)
34        }
35    }
36
37    fn approx_eq(&self, other: &Complex64, tolerance: f64) -> bool {
38        (self - other).norm() < tolerance
39    }
40
41    fn fidelity(&self, other: &Complex64) -> f64 {
42        (self.conj() * other).norm()
43    }
44}
45
46/// Helper functions for creating common quantum states
47pub mod quantum_states {
48    use super::*;
49
50    /// Create a complex number representing the |0⟩ state amplitude
51    pub fn zero_state() -> Complex64 {
52        Complex64::new(1.0, 0.0)
53    }
54
55    /// Create a complex number representing the |1⟩ state amplitude
56    pub fn one_state() -> Complex64 {
57        Complex64::new(0.0, 0.0)
58    }
59
60    /// Create a complex number representing the |+⟩ state amplitude component
61    pub fn plus_state_component() -> Complex64 {
62        Complex64::new(1.0 / std::f64::consts::SQRT_2, 0.0)
63    }
64
65    /// Create a complex number representing the |-⟩ state amplitude component
66    pub fn minus_state_component() -> Complex64 {
67        Complex64::new(1.0 / std::f64::consts::SQRT_2, 0.0)
68    }
69
70    /// Create a phase factor e^(i*theta)
71    pub fn phase_factor(theta: f64) -> Complex64 {
72        Complex64::new(theta.cos(), theta.sin())
73    }
74}
75
76#[cfg(test)]
77mod tests {
78    use super::*;
79
80    #[test]
81    fn test_probability() {
82        let c = Complex64::new(0.6, 0.8);
83        assert!((c.probability() - 1.0).abs() < 1e-10);
84    }
85
86    #[test]
87    fn test_normalize() {
88        let c = Complex64::new(3.0, 4.0);
89        let normalized = c.normalize();
90        assert!((normalized.norm() - 1.0).abs() < 1e-10);
91    }
92
93    #[test]
94    fn test_approx_eq() {
95        let c1 = Complex64::new(1.0, 0.0);
96        let c2 = Complex64::new(1.0000001, 0.0);
97        assert!(c1.approx_eq(&c2, 1e-6));
98        assert!(!c1.approx_eq(&c2, 1e-8));
99    }
100
101    #[test]
102    fn test_phase_factor() {
103        use std::f64::consts::PI;
104        let phase = quantum_states::phase_factor(PI / 2.0);
105        assert!(phase.re.abs() < 1e-10);
106        assert!((phase.im - 1.0).abs() < 1e-10);
107    }
108}
quantrs2_core/complex_ext.rs

quantrs2_core/
complex_ext.rs
