Quantum brainfuck

From Esolang

Quantum brainfuck is an esolang by Ihope127 which is essentially brainfuck operating on qubits instead of integers. The tape starts initialized with all 1's. The commands:

< Move the tape head left.
> Move the tape head right.
% Perform the Hadamard transform on the current qubit.
! Perform a controlled-V on the current qubit and the one to the right of it.
& Swap the current qubit with the one to the right of it.
, Input to the current qubit.
. Output the current qubit.
[ While observing the current qubit gives a 1...
] End while.

The controlled-V gate acts as identity, unless both the control and the target are 1, in which case they are multiplied by the imaginary unit before being returned. Output works using a CNOT, so that the output qubit and the qubit on the tape are entangled.

Controlled-V as a matrix:

[1 0 0 0]
[0 1 0 0]
[0 0 1 0]
[0 0 0 i]

[edit] External resources

• An implementation by User:lament, written in Python, is currently available:

  http://z3.ca/~lament/qubit.py

  http://z3.ca/~lament/qbf.py

  (2 files to download)

• Quantum computers on Wikipedia