Writing out and exporting

Writing out

OpenSquirrel's native tongue is cQASM. Accordingly, it is straightforward to write out a circuit, since the string representation of a circuit is a cQASM string.

Use the Python built-in methods str or print to obtain the cQASM string of the circuit.

In the case of the example program that we compiled in the previous section, we simply do the following to write out the circuit:

# To return the cQASM string
cqasm_string = str(circuit)

# To print the cQASM string
print(circuit)

Exporting

Alternatively, it is possible to export the circuit to a different format. This can be done by using the export method with the desired format as an input argument.

For instance, if we want to export our circuit to cQASM 1.0 (given by the export format CQASM_V1) we write the following:

from opensquirrel.passes.exporter import ExportFormat

exported_circuit = circuit.export(fmt=ExportFormat.CQASM_V1)

This uses the cQASMv1 exporter to export the circuit to a cQASM 1.0 string.

print(exported_circuit) # Compiled program in terms of cQASM 1.0

version 1.0

qubits 3

prep_z q[0]
prep_z q[1]
prep_z q[2]
rz q[0], 1.5707963
x90 q[0]
rz q[0], 1.5707963
rz q[1], 1.5707963
x90 q[1]
rz q[1], -1.5707963
cz q[0], q[1]
rz q[1], -1.5707963
x90 q[1]
rz q[1], 1.5707963
rz q[0], 1.5707963
x90 q[0]
rz q[0], -1.5707963
cz q[1], q[0]
rz q[0], -1.5707963
x90 q[0]
rz q[0], 1.5707963
rz q[1], 1.5707963
x90 q[1]
rz q[1], -1.5707963
cz q[0], q[1]
rz q[1], -1.5707963
x90 q[1]
rz q[1], 1.5707963
rz q[2], 1.5707963
x90 q[2]
rz q[2], -1.5707963
cz q[1], q[2]
rz q[2], -1.5707963
x90 q[2]
rz q[2], 1.5707963
barrier q[1, 0, 2]
measure_z q[1]
measure_z q[2]

Note that there may be language constructs that do not have a straightforward translation from cQASM to the chosen format. For example, cQASM 1.0 does not support the declaration of bit registers. Consequently, any information regarding bit registers and variables will be lost-in-translation, e.g., in cQASM 1.0, measurement outcomes cannot be written to a specific bit register variable even if this has been done in the original cQASM program.

Translation is not always straightforward

Make sure to check the documentation on the specific exporters to understand how the translation is done, since not all language constructs can be straightforwardly translated from cQASM into any alternative format.