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Shor Algorithm Quantum Phase Estimation (QPE) Calculator

Shor algorithm factors large composite integers N in polynomial time using Quantum Phase Estimation (QPE).

Number to factorize (e.g. RSA modulus).

Desired confidence of continuous fraction phase recovery (0.01 - 0.99).

Calculated Result
38 qubits

Total Qubits Required

Evaluation Qubits (t)

27 qubits

Work Register Qubits (L)

11 qubits

Phase Resolution

2^-27

Calculation Breakdown

  1. Register LengthL = ⌈log₂(N)⌉ = ⌈log₂(2048)⌉ = 11 bits
  2. Evaluation Qubitst = 2L + 1 + ⌈log₂(2 + 1/(2ε))⌉ = 23 + 4 = 27 qubits

What Is the Shor Algorithm Quantum Phase Estimation (QPE) Calculator?

Shor algorithm is a quantum polynomial-time algorithm for finding the prime factors of an integer N.

How Does the Shor Algorithm Quantum Phase Estimation (QPE) Calculator Work?

Converts factorization into order-finding, then evaluates eigenvalue phases using QFT.

Shor Algorithm Quantum Phase Estimation (QPE) Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

L = lceil log_2 N ceil, quad t = 2L + 1 + leftlceil log_2left(2 + rac{1}{2epsilon} ight) ight ceil, quad n_{ ext{qubits}} = t + L

Register sizing for modular exponentiation and Quantum Fourier Transform phase estimation.

How to Use the Shor Algorithm Quantum Phase Estimation (QPE) Calculator

  1. Enter the integer N to factor and desired probability target of successful single-shot phase identification.

Step-by-Step Example Calculation

Factoring 11-Bit Number (N = 2048)

Input Values:

compositeNumberN:2048
successProbabilityTarget:0.95
Worked Steps: Requires L = 11 work qubits, t = 27 phase qubits, and 38 total logical qubits.

Understanding Your Result

Displays the minimum logical qubit budget needed for the upper and lower quantum registers.

Factors That Affect the Result

  • Phase precision requires at least 2L bits to ensure continued fraction expansion uniquely resolves the period.

When Should You Use This Calculator?

  • Cryptographic vulnerability assessment and quantum hardware requirement modeling.

Assumptions & Limitations

  • Applies to logical error-corrected qubits; physical qubit counts are typically 1000x higher.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard sizing criteria from Nielsen & Chuang Quantum Computation.

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