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phase_rotation_operator

tensor4all_quanticstransform

Function phase_rotation_operator 

Source 
pub fn phase_rotation_operator(
    r: usize,
    theta: f64,
) -> Result<LinearOperator<TensorDynLen, usize>>
Expand description

Create a phase rotation operator: f(x) = exp(iθx) * g(x)

This MPO multiplies a function g(x) by the phase factor exp(iθx).

In quantics representation, x = Σ_n x_n * 2^(R-n), so: exp(iθx) = Π_n exp(iθ2^(R-n)*x_n)

Each site contributes an independent phase factor, making this a diagonal operator with bond dimension 1.

§Arguments

  • r - Number of bits (sites)
  • theta - Phase angle in radians

§Returns

LinearOperator representing the phase rotation

§Examples

use tensor4all_quanticstransform::phase_rotation_operator;
use std::f64::consts::PI;

// Create phase rotation by π/4 for 4-bit quantics
let op = phase_rotation_operator(4, PI / 4.0).unwrap();

// The operator has one MPO tensor per bit
assert_eq!(op.mpo.node_count(), 4);

// Phase rotation is a diagonal operator (bond dimension 1)
// Error on invalid input
assert!(phase_rotation_operator(0, 1.0).is_err());
assert!(phase_rotation_operator(4, f64::NAN).is_err());
assert!(phase_rotation_operator(4, f64::INFINITY).is_err());