Skip to content

Corrected CNOT success probability #38

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
DeDuckProject merged 2 commits into from
Jul 15, 2025
Merged

Corrected CNOT success probability #38

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
3c917ed
Corrected CNOT success probability
Lavi101 Jul 14, 2025
be5d859
No code duplicate fix
Lavi101 Jul 14, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
20 changes: 10 additions & 10 deletions src/engine/operations.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -99,23 +99,23 @@ export const bilateralCNOT = (control: DensityMatrix, target: DensityMatrix): {
// In the BBPSSW protocol with |Φ⁺⟩ as the target state after exchange,
// the success probability depends on the fidelity F
const f = control.get(0, 0).re;

// Calculate improved fidelity after successful purification
// F' = (f^2 + (1-f)^2/9) / (f^2 + 2f(1-f)/3 + 5(1-f)^2/9)
const numerator = f * f + Math.pow(1 - f, 2) / 9;
const denominator = f * f + 2 * f * (1 - f) / 3 + 5 * Math.pow(1 - f, 2) / 9;
// Handle potential division by zero or NaN
const fPrime = denominator === 0 ? 0 : numerator / denominator;

// Success probability is p_success = f^2 + (1-f)^2/9
const successProbability = f * f + (1 - f) * (1 - f) / 9;
// Success probability is p_success = f^2 + 2 f (1-f) / 3 + 5 (1-f)^2 /9
const successProbability = denominator

// Determine success based on probability
const successful = Math.random() < successProbability;

let controlPair: DensityMatrix;

if (successful) {
// Calculate improved fidelity after successful purification
// F' = (f^2 + (1-f)^2/9) / (f^2 + 2f(1-f)/3 + 5(1-f)^2/9)
const numerator = f * f + Math.pow(1 - f, 2) / 9;
const denominator = f * f + 2 * f * (1 - f) / 3 + 5 * Math.pow(1 - f, 2) / 9;
// Handle potential division by zero or NaN
const fPrime = denominator === 0 ? 0 : numerator / denominator;

// Create new density matrix directly and set elements
const controlPairResult = new DensityMatrix(Array(4).fill(0).map(() => Array(4).fill(0).map(() => ComplexNum.zero())));
controlPairResult.set(0, 0, new ComplexNum(fPrime, 0));
Expand Down Expand Up @@ -168,4 +168,4 @@ export const preparePairsForCNOT = (pairs: QubitPair[]): {
targetPairs,
hasUnpairedPair
};
};
};