Assembly declaration

Assembly declarations can be used to add backend-specific (assembly) code to a cQASM circuit. They are realized through an asm declaration statement. An asm declaration statement consists of the keyword asm with the identifier of the backend in parentheses, followed by the backend code. The latter is to be provided as a raw text string, which consists of a raw text delimited by opening and closing triple quotes ('''):

  asm(backend-identifier) backend-code

Grammar for assembly declaration

assembly-declaration:
  asm(backend-identifier) backend-code

backend-identifier:
  identifier

backend-code:
  raw-text-string

As part of a cQASM circuit, the contents of the raw text string will be passed verbatim to the backend and ignored by all other consumers of the circuit.

The location of the asm declaration in the cQASM circuit is preserved, i.e., no cQASM statements can be moved across it by any subsequent processing of the cQASM circuit. This allows for the ability to embed backend code into cQASM with the guarantee that the relative order between cQASM and backend code remains the same.

The following example shows how sections of code, specific to the example Backend, can be interlaced with cQASM statements:

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version 3.0

qubit[4] q
bit[2]

asm(Backend) '''
    POS(0, 0) q[0]
    POS(1, 0) q[1]
    POS(0, 1) q[2]
    POS(1, 1) q[3]
'''

init q

X q[0]

asm(Backend) '''
    PULSE(0.000467, -0.971166, 0.157596)
    PULSE(0.001868, -0.942333, 0.157596)
    PULSE(0.004196, -0.913500, 0.157596)
    PULSE(0.007442, -0.884666, 0.157596)
'''

H q
CNOT q[0], q[1]

b = measure q[0, 1]