Essays
Longer pieces. Each one ends with the same four lines: what was claimed, what the evidence actually shows, what is missing, and why it matters.
The difficulty label says what a piece assumes, not how hard it is. Intro assumes no background beyond an interest in the subject. Intermediate assumes you have met qubits, gates and error rates before. Advanced assumes you read papers in this field and want the argument rather than the introduction.
Foundations
-
A deadline in cryptography is not a deadline in hardware
Migration deadlines for post-quantum cryptography are real and worth meeting. They are not predictions about when a quantum computer will exist, and reading them that way gets the whole subject backwards.
-
How to read a quantum claim
A procedure for taking any quantum announcement apart: find the number, find the comparison, find the conditions, and find out who checked. Most claims fail before the third step.
-
A physical qubit is not a computer
Qubit count is the number a manufacturer can most easily make go up, and the number that tells you least. Here is what the other numbers are, and why errors compound faster than registers grow.
-
What a logical qubit actually is
The word “logical qubit” is now used for at least four different things, only one of which is the thing that matters. This is how to tell which one an announcement means.
Hardware & error
-
The decoder has to keep up
Error correction is usually described as a code. In operation it is a classical computing problem with a deadline, and the deadline is set by the measurement cycle rather than by the physics.
Tooling
-
When a tooling release is actually news
Most quantum software releases are version numbers. A small number change what a practitioner can run, and the difference is visible in the changelog if you know which three questions to ask of it.
Applications & limits
-
Why advantage demos keep disappearing
Quantum advantage claims have a habit of shrinking after publication. The reason is structural, not scandalous, and understanding it tells you how much weight any new claim can carry.