Inspecting the circuit
Quantum circuits in Amazon Braket have a pseudo-time concept called
Moments
. Each qubit can experience a single gate per
Moment
. The purpose of Moments
is to make circuits and
their gates easier to address and to provide a temporal structure.
Note
Moments generally do not correspond to the real time at which gates are executed on a QPU.
The depth of a circuit is given by the total number of Moments in that circuit. You
can view the circuit depth calling the method circuit.depth
as shown in the
following example.
# define a circuit with parametrized gates circ = Circuit().rx(0, 0.15).ry(1, 0.2).cnot(0,2).zz(1, 3, 0.15).x(0) print(circ) print('Total circuit depth:', circ.depth)
T : | 0 | 1 |2| q0 : -Rx(0.15)-C----------X- | q1 : -Ry(0.2)--|-ZZ(0.15)--- | | q2 : ----------X-|---------- | q3 : ------------ZZ(0.15)--- T : | 0 | 1 |2| Total circuit depth: 3
The total circuit depth of the circuit above is 3 (shown as moments 0
,
1
, and 2
). You can check the gate operation for each
moment.
Moments
functions as a dictionary of key-value
pairs.
-
The key is
MomentsKey()
, which contains pseudo-time and qubit information. -
The value is assigned in the type of
Instructions()
.
moments = circ.moments for key, value in moments.items(): print(key) print(value, "\n")
MomentsKey(time=0, qubits=QubitSet([Qubit(0)])) Instruction('operator': Rx('angle': 0.15, 'qubit_count': 1), 'target': QubitSet([Qubit(0)])) MomentsKey(time=0, qubits=QubitSet([Qubit(1)])) Instruction('operator': Ry('angle': 0.2, 'qubit_count': 1), 'target': QubitSet([Qubit(1)])) MomentsKey(time=1, qubits=QubitSet([Qubit(0), Qubit(2)])) Instruction('operator': CNot('qubit_count': 2), 'target': QubitSet([Qubit(0), Qubit(2)])) MomentsKey(time=1, qubits=QubitSet([Qubit(1), Qubit(3)])) Instruction('operator': ZZ('angle': 0.15, 'qubit_count': 2), 'target': QubitSet([Qubit(1), Qubit(3)])) MomentsKey(time=2, qubits=QubitSet([Qubit(0)])) Instruction('operator': X('qubit_count': 1), 'target': QubitSet([Qubit(0)]))
You can also add gates to a circuit through Moments
.
new_circ = Circuit() instructions = [Instruction(Gate.S(), 0), Instruction(Gate.CZ(), [1,0]), Instruction(Gate.H(), 1) ] new_circ.moments.add(instructions) print(new_circ)
T : |0|1|2| q0 : -S-Z--- | q1 : ---C-H- T : |0|1|2|