SEEQuant
Menu
ENES
Try Syndrome

Seetrex's quantum line

Interactive quantum software.

Software to understand, test and build with quantum computing.

Try SyndromeSee the lab

  • 0installs: it runs in the browser
  • PyMatchingresults validated against the reference
  • Mobileand desktop
  • EN · ESin two languages

Syndrome: more qubits, fewer errors

A quantum computer makes mistakes. Error correction spreads one “logical” qubit across many physical qubits and keeps watching for where faults appear. The idea sounds backwards: if every physical qubit can fail, why would things get better with more of them?

Syndrome lets you try it with your own hands. You place errors on a surface code grid, see the signals they leave and watch the decoder pair those signals up to correct them. The chart answers the question: as long as the hardware stays below a threshold, every increase in code size lowers the logical error rate. This is what Google demonstrated with its Willow chip (Nature, 2025).

Syndrome’s chart: logical error rate against physical error probability for sizes d = 3, 5 and 7, on a logarithmic scale. Left of the crossing, the d = 7 curve lies below the d = 5 curve, which lies below the d = 3 curve.

Syndrome's chart with independent X/Z noise and perfect measurements. Left of the point where the curves cross, the larger code makes fewer errors. What the chart says, with its figures.

Syndrome’s results are compared with PyMatching, the reference decoder that researchers use, point by point and with a statistical criterion fixed in advance. How we check it.

Open Syndrome

What we are building

SEEQuant has three open lines of work. None has a date: a tool is published when it is finished and verified.

Would you use it in class or with your team?

We are exploring educational software for schools, universities and companies. Tell us what you need: it helps us decide what to build.

Go to Classroom