Quantum Computation Language: Difference between revisions

Revision as of 11:22, 4 September 2018

Revision as of 12:01, 4 September 2018

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The basic built-in quantum data type in QCL is the qureg (quantum register). It can be interpreted as an array of qubits (quantum bits).

<syntaxhighlight lang="cpp">

qureg x1[2]; // 2-qubit quantum register x1

qureg x2[2]; // 2-qubit quantum register x2

H(x1); // Hadamard operation on x1

H(x2[1]); // Hadamard operation on the first qubit of the register x2

</syntaxhighlight>

Since the qcl interpreter uses qlib simulation library, it is possible to observe the internal state of the quantum machine during execution of the quantum program.

<syntaxhighlight lang="text">

qcl> dump

: STATE: 4 / 32 qubits allocated, 28 / 32 qubits free

0.35355 |0> + 0.35355 |1> + 0.35355 |2> + 0.35355 |3>

+ 0.35355 |8> + 0.35355 |9> + 0.35355 |10> + 0.35355 |11>

</syntaxhighlight>

Note that the dump operation is different from measurement, since it does not influence the state of the quantum machine and can be realized only using a simulator.

Like in modern programming languages, it is possible to define new operations which can be used to manipulate quantum data. For example:

<sourcesyntaxhighlight lang="cpp">

operator diffuse (qureg q) {

H(q); // Hadamard Transform

Not(q); // Invert q

CPhase(pi, q); // Rotate if q=1111..

!Not(q); // undo inversion

!H(q); // undo Hadamard Transform

}

}

</syntaxhighlight>

</source>

defines inverse about the mean operator used in [[Grover's algorithm]]. This allows one to define algorithms on a higher level of abstraction and extend the library of functions available for programmers.

== References ==

{{reflist}}

[[Category:Programming languages]]