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The Notebook Ledger

Know what actually changed in quantum this week

A free Monday briefing for investors: what changed, which claims hold up, and what to watch.

Free. One email on Monday mornings. Unsubscribe anytime.

What you get each Monday

  • What changed, company by company

    Short cards for each public quantum company in the news: what actually changed this week, how far along it is, and why it matters.

  • Claims checked against evidence

    The week’s headline claims in one table, each tagged by evidence strength: measured, estimated, simulated, announced, or conditional.

  • Watch list and full sources

    What to revisit in the weeks ahead, plus links to every paper, filing, and announcement behind the issue.

From a sample issue

What a Monday issue looks like

$IONQ

Week of October 7–14, 2026

What changed

  • Agreed to acquire Elisity for up to $1.3B in stock, including up to $150M tied to performance. Expected to close in Q4 2026, subject to approvals.
  • Selected for DARPA QBI Stage C. The agreement is worth up to $300M, with funding beyond the initial obligation conditional, and the work runs through 2029.
  • Published the experiment behind its 1,000-pairs-per-second quantum link: 1,032 pairs/s at 87.9% Bell-state fidelity.

Evidence level

  • Elisity: Announced; not closed.
  • DARPA: Selected; funding conditional.
  • Quantum link: Measured.

Watch next

  • Elisity close and integration.
  • Stage C test results.
  • Higher fidelity and throughput on the quantum link, needed for error-corrected networking.
ClaimCompanyEvidenceStatus this week
1,000 entangled pairs/s ion–diamond linkIonQMeasuredSupported: 1,032/s at 87.9% fidelity; 612/s with verification
~99% CNOT from 37 exchangesHRL / IBMEstimateNot demonstrated
~10× lower effective error vs IBM BostonQuantinuumMeasured (3rd party)Error-correction operations, not corrected qubits

Who it’s for

Investors and curious readers who follow quantum companies and want to separate real technical progress from press-release momentum, without reading every paper themselves.

The Ledger is written science first: every claim is traced to its source and labeled by how strong the evidence is. It does not rate stocks or tell you what to buy or sell.

Questions

Is it free?
Yes. The Notebook Ledger is free.
Does it include stock picks?
No. There are no ratings, price targets, or buy and sell recommendations.
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One email, on Monday mornings, New York time.
Can I unsubscribe?
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