def run_single_algorithm(algorithm, num_qubits, num_samples=8000):
"""
Create a quantum circuit, run the algorithm, return the resulting
probability distribution.
algorithm: algorithm (list of strings),
each string is a gate, ie "cx(0, 1)" or "rx(pi/2, 0)"
num_qubits: int, number of qubits to run each algorithm on. Can be None,
in which case the algorithm will be run on the minimum
number of qubits required.
num_samples: int, number of samples to take from the quantum computer in
in order to determine the probabilities for each state.
returns: dict (common.Result), keys are states, values are probabilities
found to be in that state.
"""
eng = MainEngine()
qureg = eng.allocate_qureg(num_qubits)
measure = []
for gate in algorithm:
if "measure" not in gate.lower(): apply_gate(gate, qureg)
else:
_, gate_args = get_gate_info(gate)
measure.append(gate_args[0])
if not measure: measure = list(range(num_qubits))
eng.flush()
to_measure = [qureg[i] for i in measure]
#TODO: find supported projectq way to do this with out iterating O(2^n)!
res = {}
for x in range(2**len(measure)):
state = ("{0:0%db}" % len(to_measure)).format(x)
res[state] = eng.backend.get_probability(state, to_measure)
# so projectq doesn't throw an error
ops.All(ops.Measure) | qureg
# To have a realistic simulator, we need to sample, not just return the
# probabilities.
samples = {}
for _ in range(num_samples):
r = random.random()
for state, prob in res.items():
r -= prob
if r <= 0:
if state in samples: samples[state] += 1
else: samples[state] = 1
break
return Result(
{state: counts / num_samples
for state, counts in samples.items()})
def createProgram(qubits, inputValue, errorIdxs):
PrepareState(qubits, inputValue)
PhaseFlipEncode(qubits, [0, 3, 6])
BitFlipEncode(qubits, [0, 1, 2])
BitFlipEncode(qubits, [3, 4, 5])
BitFlipEncode(qubits, [6, 7, 8])
ErrorIntroduction(qubits, errorIdxs)
BitFlipDecode(qubits, [0, 1, 2])
BitFlipDecode(qubits, [3, 4, 5])
BitFlipDecode(qubits, [6, 7, 8])
PhaseFlipDecode(qubits, [0, 3, 6])
ops.Measure | qubits[
0] # Only the first bit is of importance. All others are to encode the state
ops.All(ops.Measure) | qubits[1:] # All other qubits should be zero
return qubits
def test_Measure(benchmark, nqubits):
benchmark.group = "Measure"
run_bench(benchmark, ops.All(ops.Measure), None, nqubits)