Superdense-coding classical capacity

A noiseless qubit channel assisted by one shared ebit transmits two classical bits per use.

Specification version 1Published 1992-11-091 evidence records

About this problem

The question, scope, and sources behind this Registry record.

Formal question

Determine classical messages conveyed by one noiseless transmitted qubit when sender and receiver share one Bell pair.

Scope & constraints

channel: noiseless qubit
decoding: Bell measurement
encoding: local Pauli operations
sharedEntanglement: one Bell pair

Primary sources

Communication via one- and two-particle operators on Einstein-Podolsky-Rosen states — Superdense-coding classical capacity = Dense-coding protocol

What we know

Current frontiers derived from accepted Claims.

Exact established value2 classical bits per transmitted qubit with 1 shared ebit

The accepted equality closes this optimization result.

Claims

Assertions tied to evidence, attribution, and review.

2026

CLM-QUANT-003305-1= 2 classical bits per transmitted qubit with 1 shared ebitEXACT VALUEThe cited theorem establishes 2 classical bits per transmitted qubit with 1 shared ebit under the recorded assumptions.Source: Communication via one- and two-particle operators on Einstein-Podolsky-Rosen states — Superdense-coding classical capacity = ↗

PROVEN

Timeline

The frontier as it changed over time.

How this frontier is derived

Only accepted Claims matching the current specification contribute to the displayed bounds. Strict inequalities remain open; contradictory Claims require editorial review.

—No breakthrough events recorded yetEvents appear here when an accepted Claim tightens a bound or closes the frontier.

Specification

What question is being asked?

Constraints: channel=noiseless qubit · decoding=Bell measurement · encoding=local Pauli operations · sharedEntanglement=one Bell pair

Read full specification ↗

Corrections & disputes

Record history

No unresolved corrections or disputes are recorded for this published version.

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Editorial status

Evidence-backed record

1 accepted Claim, with 1 linked evidence records.

Human-reviewed · No AI-only claims

Verified prizes & bounties

Active verified incentives

No active verified bounties are linked to this Limit.

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Reproducibility

Machine-checked history

No accepted machine-checked reproductions are recorded for this Limit.

Cite this LimitLimits Registry. LR-003305. Superdense-coding classical capacity. 2026.