Measure instruction

A measure instruction performs a measurement to its qubit argument and assigns the outcome to a bit variable. The general form of a measure instruction is as follows:

 bit-argument = measure qubit-argument

Grammar for measure instruction

measure-instruction:
  bit-argument = measure qubit-argument

bit-argument:
  bit-variable
  bit-index

bit-variable:
  identifier

bit-index:
  index

qubit-argument:
  qubit-variable
  qubit-index

qubit-variable:
  identifier

qubit-index:
  index

Example

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qubit q
bit b
b = measure q

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qubit[5] q
bit[2] b
b[0, 1] = measure q[2, 4]

Note

The measure instruction accepts SGMQ notation, similar to gates.

The following code snippet shows how the measure instruction might be used in context.

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version 3.0

qubit[2] q
bit[2] b

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

b = measure q  // Measurement in the standard basis.

On the last line of this simple cQASM program, the respective states of both qubits in the qubit register are measured along the standard/computational basis.