BB84 Sift Error Analysis

Sift aligned BB84 records and calculate the sifted-key error rate.

Description

BB84 sifting retains positions whose sent and received basis labels match.

BB84 sifting retains positions whose sent and received basis labels match. Error rate is calculated only within those retained records.^[1]

Sift aligned BB84 records and calculate the sifted-key error rate.

When to use BB84 Sift Error Analysis

Use this tool to sift aligned BB84 records and calculate the sifted-key error rate.

Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.

How to use BB84 Sift Error Analysis and understand its results

Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
Enter sentBases, sentBits, receivedBases, receivedBits using the field table and calculation rules, then run the tool.
Read siftedBitCount, errorCount, quantumBitErrorPercent, siftedIndexes. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
sentBases	Sent bases	list of string	Required
sentBits	Sent bits	list of number	Required
receivedBases	Received bases	list of string	Required
receivedBits	Received bits	list of number	Required

Enter four nonempty aligned lists. Compare basis strings exactly and count unequal numeric bits at matching positions. Return sifted indexes, count, errors and percentage; zero retained records return percentage zero as a placeholder.

QBER%=100errors/siftedCount

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
siftedBitCount	Sifted bit count	integer; minimum: 0
errorCount	Sifted error count	integer; minimum: 0
quantumBitErrorPercent	Quantum bit error rate (%)	number; minimum: 0; maximum: 100
siftedIndexes	Sifted indexes	list of number

json

{
  "input": {
    "sentBases": [
      "Z",
      "X",
      "Z",
      "X"
    ],
    "sentBits": [
      0,
      1,
      1,
      0
    ],
    "receivedBases": [
      "Z",
      "Z",
      "Z",
      "X"
    ],
    "receivedBits": [
      0,
      0,
      0,
      0
    ]
  },
  "output": {
    "siftedBitCount": 3,
    "errorCount": 1,
    "quantumBitErrorPercent": 33.33333333333333,
    "siftedIndexes": [
      0,
      2,
      3
    ]
  }
}

Limitations and assumptions

Basis alphabets and binary bit values are not validated. No quantum exchange, privacy amplification or key-security proof is performed.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use BBO Entanglement Setup Check: Estimate a two-basis BBO entanglement CHSH value from measured visibilities. For a complementary task, use Decoy-State Intensity Score: Score supplied signal and decoy intensities from observed gains; this is not a security proof.

References

BB84 Sift Error Analysis — tool.io

Similar or alternative tools

BBO Entanglement Setup Check
Estimate a two-basis BBO entanglement CHSH value from measured visibilities.
Decoy-State Intensity Score
Score supplied signal and decoy intensities from observed gains; this is not a security proof.