# Generalised Quantum Gates

1. Mar 30, 2004

### damo642

Hi i am coding a quantum computer simulator.
the simulator will be able to work in dimensions other than qubits.
in other words the user can select either qubits(d=2), qutrits(d=
3).....etc
Obviously in this senario one must have the generalised versions of
all the gates

So far i have have found generalised versions of-

Not Gate
C-Not Gate
Swap Gate
Pauli X Gate

Ive been researching this for some months now and am finding it
impossible to
find generalised versions of any of the other common quantum gates. eg
pauli y gate toffoli gate, controlled swap gate ,controlled unitary
gate Phase gate and pi/8 gate or any other useful gates.

Essentially all i need to know is for any given dimension ( be it
qubits or qutrits etc) what is the matrix representation for a certain
gate.

ps. The current Version of my software can be found on :

http://www.compsoc.nuigalway.ie/~damo642/QuantumSimulator/QuantumSimulator/QuantumQuditSimulator.htm [Broken]

Damien

Last edited by a moderator: May 1, 2017
2. Mar 30, 2004

### slyboy

Did you see my reply on sci.physics.research? If not, I have pasted it below.

There is no unique generalization of these gates and the one that you
choose usually depends on the application you have in mind. For
example, the Pauli operators are Hermitian, unitary and form a basis
for the space of single qubit operators, but there is generally no set
of operators with all these three properties in higher dimensions. A
unitary generalization that is often used is:

X|j> = |j+1 (mod d)> Z|j> = w |j>

where w is a primitive dth root of unity. Then the operators
(X^n)(Z^m) form a unitary basis, analogous to the Pauli operators.

One possibility for a generalized controlled unitary gate which is
often used is

|i>|j> -> |i> U^i |j>

but there are many other possible generalizations.

I imagine you are looking to implement a universal set for qudits, in
which case you should take a look at:
quant-ph/0108062
quant-ph/0210049