Quantum CTF
The world's first Quantum Capture the Flag — hands-on puzzles that turn curious hackers into quantum hackers.
Play the Quantum CTF →Call for Challenges
We're inviting challenges from our community this year! Below are some past examples, with solutions, for anyone keen to flex their inner quizmaster and set a challenge of their own.
Submit a challenge →What is a CTF anyway?
A 'Capture the Flag' (CTF) is a contest where hackers earn points by solving puzzles, problems, and challenges set by the organisers. Take a look at our graphic for an overview!
Past Challenges
To give you a feel for the kind of challenges we like, here are a couple of examples. Hit Reveal Solution on each card to see how it's cracked.
XOR-bit-al
Challenge: Make a circuit that has output measurements only when the output registers c[0] xor c[1] == c[2]. Do this in ≤7 lines of OpenQASM.
OPENQASM 2.0; include "qelib1.inc"; qreg q[3]; h q[0]; cx q[0],q[1]; cx q[0],q[2]; h q;
Note that we detected 'lines' by counting semicolons in the checking code. The OpenQASM code was then converted to a quantum circuit and evaluated using the end statevector.
Picture Found
Challenge: Who is this?
Алексей Юрьевич Китаев
Yeah, you could reverse image search this, like the others — but you had to work out that, because Kitaev is Russian-born, you'd need to put his name into the answer box in Cyrillic! Hence the double points for this picture.