def single_qubit_matrix_to_phased_x_z(mat: np.ndarray,
atol: float = 0
) -> List[ops.SingleQubitGate]:
"""Implements a single-qubit operation with a PhasedX and Z gate.
If one of the gates isn't needed, it will be omitted.
Args:
mat: The 2x2 unitary matrix of the operation to implement.
atol: A limit on the amount of error introduced by the
construction.
Returns:
A list of gates that, when applied in order, perform the desired
operation.
"""
xy_turn, xy_phase_turn, total_z_turn = (
_deconstruct_single_qubit_matrix_into_gate_turns(mat))
# Build the intended operation out of non-negligible XY and Z rotations.
result = [
ops.PhasedXPowGate(exponent=2 * xy_turn,
phase_exponent=2 * xy_phase_turn),
ops.Z**(2 * total_z_turn)
]
result = [g for g in result if protocols.trace_distance_bound(g) > atol]
# Special case: XY half-turns can absorb Z rotations.
if len(result) == 2 and abs(xy_turn) >= 0.5 - atol:
return [
ops.PhasedXPowGate(phase_exponent=2 * xy_phase_turn + total_z_turn)
]
return result
def decompose_cz_into_syc(a: ops.Qid, b: ops.Qid):
"""Decompose CZ into sycamore gates using precomputed coefficients"""
yield ops.PhasedXPowGate(phase_exponent=0.5678998743900456, exponent=0.5863459345743176).on(a)
yield ops.PhasedXPowGate(phase_exponent=0.3549946157441739).on(b)
yield google.SYC.on(a, b)
yield ops.PhasedXPowGate(phase_exponent=-0.5154334589432878, exponent=0.5228733015013345).on(b)
yield ops.PhasedXPowGate(phase_exponent=0.06774925307475355).on(a)
yield google.SYC.on(a, b),
yield ops.PhasedXPowGate(phase_exponent=-0.5987667922766213, exponent=0.4136540654256824).on(a),
yield (ops.Z ** -0.9255092746611595).on(b),
yield (ops.Z ** -1.333333333333333).on(a),
def __init__(self,
qubits: Sequence['cirq.Qid'],
prerotations: Optional[Sequence[Tuple[float, float]]] = None):
"""Initializes the rotation protocol and matrix for system.
Args:
qubits: Qubits to do the tomography on.
prerotations: Tuples of (phase_exponent, exponent) parameters for
gates to apply to the qubits before measurement. The actual
rotation applied will be `cirq.PhasedXPowGate` with the
specified values of phase_exponent and exponent. If None,
we use [(0, 0), (0, 0.5), (0.5, 0.5)], which corresponds
to rotation gates [I, X**0.5, Y**0.5].
"""
if prerotations is None:
prerotations = [(0, 0), (0, 0.5), (0.5, 0.5)]
self.num_qubits = len(qubits)
phase_exp_vals, exp_vals = zip(*prerotations)
operations: List['cirq.Operation'] = []
sweeps: List['cirq.Sweep'] = []
for i, qubit in enumerate(qubits):
phase_exp = sympy.Symbol(f'phase_exp_{i}')
exp = sympy.Symbol(f'exp_{i}')
gate = ops.PhasedXPowGate(phase_exponent=phase_exp, exponent=exp)
operations.append(gate.on(qubit))
sweeps.append(
study.Points(phase_exp, phase_exp_vals) +
study.Points(exp, exp_vals))
self.rot_circuit = circuits.Circuit(operations)
self.rot_sweep = study.Product(*sweeps)
self.mat = self._make_state_tomography_matrix()
def _potential_cross_partial_w(moment_index: int,
op: ops.Operation,
state: _OptimizerState) -> None:
"""Cross the held W over a partial W gate.
[Where W(a) is shorthand for PhasedX(phase_exponent=a).]
Uses the following identity:
───W(a)───W(b)^t───
≡ ───Z^-a───X───Z^a───W(b)^t────── (expand W(a))
≡ ───Z^-a───X───W(b-a)^t───Z^a──── (move Z^a across, phasing axis)
≡ ───Z^-a───W(a-b)^t───X───Z^a──── (move X across, negating axis angle)
≡ ───W(2a-b)^t───Z^-a───X───Z^a─── (move Z^-a across, phasing axis)
≡ ───W(2a-b)^t───W(a)───
"""
a = state.held_w_phases.get(op.qubits[0])
if a is None:
return
exponent, phase_exponent = cast(Tuple[float, float],
_try_get_known_phased_pauli(op))
new_op = ops.PhasedXPowGate(
exponent=exponent,
phase_exponent=2 * a - phase_exponent).on(op.qubits[0])
state.deletions.append((moment_index, op))
state.inline_intos.append((moment_index, new_op))
def xmon_op_from_proto(proto: operations_pb2.Operation) -> 'cirq.Operation':
"""Convert the proto to the corresponding operation.
See protos in api/google/v1 for specification of the protos.
Args:
proto: Operation proto.
Returns:
The operation.
"""
param = _parameterized_value_from_proto
qubit = _qubit_from_proto
if proto.HasField('exp_w'):
exp_w = proto.exp_w
return ops.PhasedXPowGate(
exponent=param(exp_w.half_turns),
phase_exponent=param(exp_w.axis_half_turns),
).on(qubit(exp_w.target))
if proto.HasField('exp_z'):
exp_z = proto.exp_z
return ops.Z(qubit(exp_z.target))**param(exp_z.half_turns)
if proto.HasField('exp_11'):
exp_11 = proto.exp_11
return ops.CZ(qubit(exp_11.target1),
qubit(exp_11.target2))**param(exp_11.half_turns)
if proto.HasField('measurement'):
meas = proto.measurement
return ops.MeasurementGate(num_qubits=len(meas.targets),
key=meas.key,
invert_mask=tuple(meas.invert_mask)).on(
*[qubit(q) for q in meas.targets])
raise ValueError(f'invalid operation: {proto}')
def _potential_cross_partial_w(
op: ops.Operation,
held_w_phases: Dict[ops.Qid, value.TParamVal],
) -> 'cirq.OP_TREE':
"""Cross the held W over a partial W gate.
[Where W(a) is shorthand for PhasedX(phase_exponent=a).]
Uses the following identity:
───W(a)───W(b)^t───
≡ ───Z^-a───X───Z^a───W(b)^t────── (expand W(a))
≡ ───Z^-a───X───W(b-a)^t───Z^a──── (move Z^a across, phasing axis)
≡ ───Z^-a───W(a-b)^t───X───Z^a──── (move X across, negating axis angle)
≡ ───W(2a-b)^t───Z^-a───X───Z^a─── (move Z^-a across, phasing axis)
≡ ───W(2a-b)^t───W(a)───
"""
a = held_w_phases.get(op.qubits[0], None)
if a is None:
return op
exponent, phase_exponent = cast(
Tuple[value.TParamVal, value.TParamVal], _try_get_known_phased_pauli(op)
)
new_op = ops.PhasedXPowGate(exponent=exponent, phase_exponent=2 * a - phase_exponent).on(
op.qubits[0]
)
return new_op
def _random_half_rotations(qubits: Sequence[ops.Qid], num_layers: int) -> List[List[ops.OP_TREE]]:
rot_ops = [ops.X ** 0.5, ops.Y ** 0.5, ops.PhasedXPowGate(phase_exponent=0.25, exponent=0.5)]
num_qubits = len(qubits)
rand_nums = np.random.choice(3, (num_qubits, num_layers))
single_q_layers = [] # type: List[List[ops.OP_TREE]]
for i in range(num_layers):
single_q_layers.append([rot_ops[rand_nums[j, i]](qubits[j]) for j in range(num_qubits)])
return single_q_layers
def _dump_held(qubits: Iterable[ops.Qid], moment_index: int, state: _OptimizerState):
# Note: sorting is to avoid non-determinism in the insertion order.
for q in sorted(qubits):
p = state.held_w_phases.get(q)
if p is not None:
dump_op = ops.PhasedXPowGate(phase_exponent=p).on(q)
state.insertions.append((moment_index, dump_op))
state.held_w_phases.pop(q, None)
def xmon_op_from_proto_dict(proto_dict: Dict) -> 'cirq.Operation':
"""Convert the proto dictionary to the corresponding operation.
See protos in api/google/v1 for specification of the protos.
Args:
proto_dict: Dictionary representing the proto. Keys are always
strings, but values may be types correspond to a raw proto type
or another dictionary (for messages).
Returns:
The operation.
Raises:
ValueError if the dictionary does not contain required values
corresponding to the proto.
"""
def raise_missing_fields(gate_name: str):
raise ValueError('{} missing required fields: {}'.format(
gate_name, proto_dict))
param = _parameterized_value_from_proto_dict
qubit = _qubit_from_proto_dict
if 'exp_w' in proto_dict:
exp_w = proto_dict['exp_w']
if ('half_turns' not in exp_w or 'axis_half_turns' not in exp_w
or 'target' not in exp_w):
raise_missing_fields('ExpW')
return ops.PhasedXPowGate(
exponent=param(exp_w['half_turns']),
phase_exponent=param(exp_w['axis_half_turns']),
).on(qubit(exp_w['target']))
if 'exp_z' in proto_dict:
exp_z = proto_dict['exp_z']
if 'half_turns' not in exp_z or 'target' not in exp_z:
raise_missing_fields('ExpZ')
return ops.Z(qubit(exp_z['target']))**param(exp_z['half_turns'])
if 'exp_11' in proto_dict:
exp_11 = proto_dict['exp_11']
if ('half_turns' not in exp_11 or 'target1' not in exp_11
or 'target2' not in exp_11):
raise_missing_fields('Exp11')
return ops.CZ(qubit(exp_11['target1']),
qubit(exp_11['target2']))**param(exp_11['half_turns'])
if 'measurement' in proto_dict:
meas = proto_dict['measurement']
invert_mask = cast(Tuple[Any, ...], ())
if 'invert_mask' in meas:
invert_mask = tuple(
_load_json_bool(x) for x in meas['invert_mask'])
if 'key' not in meas or 'targets' not in meas:
raise_missing_fields('Measurement')
return ops.MeasurementGate(
num_qubits=len(meas['targets']),
key=meas['key'],
invert_mask=invert_mask).on(*[qubit(q) for q in meas['targets']])
raise ValueError('invalid operation: {}'.format(proto_dict))
def test_expw_matrix(half_turns, axis_half_turns):
m1 = xmon_gates.ExpWGate(half_turns=half_turns,
axis_half_turns=axis_half_turns).matrix
if (version[0] == 0 and version[1] <= 3):
m2 = google.ExpWGate(half_turns=half_turns,
axis_half_turns=axis_half_turns).matrix()
else:
m2 = unitary(ops.PhasedXPowGate(exponent=half_turns,
phase_exponent=axis_half_turns))
nptest.assert_array_almost_equal(m1, m2)
def _dump_held(
qubits: Iterable[ops.Qid],
held_w_phases: Dict[ops.Qid, value.TParamVal]) -> 'cirq.OP_TREE':
# Note: sorting is to avoid non-determinism in the insertion order.
for q in sorted(qubits):
p = held_w_phases.get(q)
if p is not None:
dump_op = ops.PhasedXPowGate(phase_exponent=p).on(q)
yield dump_op
held_w_phases.pop(q, None)
def decompose_swap_into_syc(a: ops.Qid, b: ops.Qid):
"""Decompose SWAP into sycamore gates using precomputed coefficients"""
yield ops.PhasedXPowGate(phase_exponent=0.44650378384076217, exponent=0.8817921214052824).on(a)
yield ops.PhasedXPowGate(phase_exponent=-0.7656774060816165, exponent=0.6628666504604785).on(b)
yield google.SYC.on(a, b)
yield ops.PhasedXPowGate(phase_exponent=-0.6277589946716742, exponent=0.5659160932099687).on(a)
yield google.SYC.on(a, b)
yield ops.PhasedXPowGate(phase_exponent=0.28890767199499257, exponent=0.4340839067900317).on(b)
yield ops.PhasedXPowGate(phase_exponent=-0.22592784059288928).on(a)
yield google.SYC.on(a, b)
yield ops.PhasedXPowGate(phase_exponent=-0.4691261557936808, exponent=0.7728525693920243).on(a)
yield ops.PhasedXPowGate(phase_exponent=-0.8150261316932077, exponent=0.11820787859471782).on(b)
yield (ops.Z ** -0.7384700844660306).on(b)
yield (ops.Z ** -0.7034535141382525).on(a)
def decompose_iswap_into_syc(a: ops.Qid, b: ops.Qid):
"""Decompose ISWAP into sycamore gates using precomputed coefficients"""
yield ops.PhasedXPowGate(phase_exponent=-0.27250925776964596, exponent=0.2893438375555899).on(a)
yield google.SYC.on(a, b)
yield ops.PhasedXPowGate(phase_exponent=0.8487591858680898, exponent=0.9749387200813147).on(b),
yield ops.PhasedXPowGate(phase_exponent=-0.3582574564210601).on(a),
yield google.SYC.on(a, b)
yield ops.PhasedXPowGate(phase_exponent=0.9675022326694225, exponent=0.6908986856555526).on(a),
yield google.SYC.on(a, b),
yield ops.PhasedXPowGate(phase_exponent=0.9161706861686068, exponent=0.14818318325264102).on(b),
yield ops.PhasedXPowGate(phase_exponent=0.9408341606787907).on(a),
yield (ops.Z ** -1.1551880579397293).on(b),
yield (ops.Z ** 0.31848343246696365).on(a),
def _expWGate(cmd, mapping, qubits):
"""
Translate a ExpW gate into a Cirq gate.
Args:
- cmd (:class:`projectq.ops.Command`) - a projectq command instance
- mapping (:class:`dict`) - a dictionary of qubit mappings
- qubits (list of :class:cirq.QubitID`) - cirq qubits
Returns:
- :class:`cirq.Operation`
"""
qb_pos = [mapping[qb.id] for qr in cmd.qubits for qb in qr]
assert len(qb_pos) == 1
cirqGate = cop.PhasedXPowGate(exponent=cmd.gate.angle / cmath.pi,
phase_exponent=cmd.gate.axis_angle /
cmath.pi)
if get_control_count(cmd) > 0:
ctrl_pos = [mapping[qb.id] for qb in cmd.control_qubits]
return cop.ControlledGate(cirqGate)(
*[qubits[c] for c in ctrl_pos + qb_pos])
else:
return cirqGate(*[qubits[idx] for idx in qb_pos])
def decompose_phased_iswap_into_syc_precomputed(theta: float, a: ops.Qid,
b: ops.Qid) -> ops.OP_TREE:
"""Decompose PhasedISwap into sycamore gates using precomputed coefficients.
This should only be called if the Gate has a phase_exponent of .25. If the
gate has an exponent of 1, decompose_phased_iswap_into_syc should be used
instead. Converting PhasedISwap gates to Sycamore is not supported if
neither of these constraints are satisfied.
This synthesize a PhasedISwap in terms of four sycamore gates. This
compilation converts the gate into a circuit involving two CZ gates, which
themselves are each represented as two Sycamore gates and single-qubit
rotations
Args:
theta: rotation parameter
a: First qubit id to operate on
b: Second qubit id to operate on
Returns:
a Cirq program implementing the Phased ISWAP gate
"""
yield ops.PhasedXPowGate(phase_exponent=0.41175161497166024,
exponent=0.5653807577895922).on(a)
yield ops.PhasedXPowGate(phase_exponent=1.0, exponent=0.5).on(b),
yield (ops.Z**0.7099892314883478).on(b),
yield (ops.Z**0.6746023442550453).on(a),
yield SycamoreGate().on(a, b)
yield ops.PhasedXPowGate(phase_exponent=-0.5154334589432878,
exponent=0.5228733015013345).on(b)
yield ops.PhasedXPowGate(phase_exponent=0.06774925307475355).on(a)
yield SycamoreGate().on(a, b),
yield ops.PhasedXPowGate(phase_exponent=-0.5987667922766213,
exponent=0.4136540654256824).on(a)
yield (ops.Z**-0.9255092746611595).on(b)
yield (ops.Z**-1.333333333333333).on(a)
yield ops.rx(-theta).on(a)
yield ops.rx(-theta).on(b)
yield ops.PhasedXPowGate(phase_exponent=0.5678998743900456,
exponent=0.5863459345743176).on(a)
yield ops.PhasedXPowGate(phase_exponent=0.3549946157441739).on(b)
yield SycamoreGate().on(a, b)
yield ops.PhasedXPowGate(phase_exponent=-0.5154334589432878,
exponent=0.5228733015013345).on(b)
yield ops.PhasedXPowGate(phase_exponent=0.06774925307475355).on(a)
yield SycamoreGate().on(a, b)
yield ops.PhasedXPowGate(phase_exponent=-0.8151665352515929,
exponent=0.8906746535691492).on(a)
yield ops.PhasedXPowGate(phase_exponent=-0.07449072533884049,
exponent=0.5).on(b)
yield (ops.Z**-0.9255092746611595).on(b)
yield (ops.Z**-0.9777346353961884).on(a)
def random_rotations_between_grid_interaction_layers_circuit(
qubits: Iterable['cirq.GridQubit'],
depth: int,
*, # forces keyword arguments
two_qubit_op_factory: Callable[
['cirq.GridQubit', 'cirq.GridQubit', 'np.random.RandomState'],
'cirq.OP_TREE'] = lambda a, b, _: google.SYC(a, b),
pattern: Sequence[GridInteractionLayer] = GRID_STAGGERED_PATTERN,
single_qubit_gates: Sequence['cirq.Gate'] = (ops.X**0.5, ops.Y**0.5,
ops.PhasedXPowGate(
phase_exponent=0.25,
exponent=0.5)),
add_final_single_qubit_layer: bool = True,
seed: value.RANDOM_STATE_LIKE = None,
) -> 'cirq.Circuit':
"""Generate a random quantum circuit.
This construction is based on the circuits used in the paper
https://www.nature.com/articles/s41586-019-1666-5.
The generated circuit consists of a number of "cycles", this number being
specified by `depth`. Each cycle is actually composed of two sub-layers:
a layer of single-qubit gates followed by a layer of two-qubit gates.
The single-qubit gates are chosen randomly from the gates specified by
`single_qubit_gates`, but with the constraint that no qubit is acted upon
by the same single-qubit gate in consecutive cycles. In the layer of
two-qubit gates, which pairs of qubits undergo interaction is determined
by `pattern`, which is a sequence of two-qubit interaction sets. The
set of interactions in a two-qubit layer rotates through this sequence.
The two-qubit operations themselves are generated by the call
`two_qubit_op_factory(a, b, prng)`, where `a` and `b` are the qubits and
`prng` is the pseudorandom number generator.
At the end of the circuit, an additional layer of single-qubit gates is
appended, subject to the same constraint regarding consecutive cycles
described above.
If only one choice of single-qubit gate is given, then the constraint
that excludes repeating single-qubit gates in consecutive cycles is not
enforced.
Args:
qubits: The qubits to use.
depth: The number of cycles.
two_qubit_op_factory: A factory to generate two-qubit operations.
These operations will be generated with calls of the form
`two_qubit_op_factory(a, b, prng)`, where `a` and `b` are the qubits
to operate on and `prng` is the pseudorandom number generator.
pattern: The pattern of grid interaction layers to use.
single_qubit_gates: The single-qubit gates to use.
add_final_single_qubit_layer: Whether to include a final layer of
single-qubit gates after the last cycle.
seed: A seed or random state to use for the pseudorandom number
generator.
"""
prng = value.parse_random_state(seed)
qubits = list(qubits)
coupled_qubit_pairs = _coupled_qubit_pairs(qubits)
circuit = circuits.Circuit()
previous_single_qubit_layer = {} # type: Dict[cirq.GridQubit, cirq.Gate]
if len(set(single_qubit_gates)) == 1:
single_qubit_layer_factory = _FixedSingleQubitLayerFactory(
{q: single_qubit_gates[0]
for q in qubits}) # type: _SingleQubitLayerFactory
else:
single_qubit_layer_factory = _RandomSingleQubitLayerFactory(
qubits, single_qubit_gates, prng)
for i in range(depth):
single_qubit_layer = single_qubit_layer_factory.new_layer(
previous_single_qubit_layer)
two_qubit_layer = _two_qubit_layer(coupled_qubit_pairs,
two_qubit_op_factory,
pattern[i % len(pattern)], prng)
circuit.append([g.on(q) for q, g in single_qubit_layer.items()],
strategy=circuits.InsertStrategy.NEW_THEN_INLINE)
circuit.append(two_qubit_layer,
strategy=circuits.InsertStrategy.EARLIEST)
previous_single_qubit_layer = single_qubit_layer
if add_final_single_qubit_layer:
final_single_qubit_layer = single_qubit_layer_factory.new_layer(
previous_single_qubit_layer)
circuit.append([g.on(q) for q, g in final_single_qubit_layer.items()],
strategy=circuits.InsertStrategy.NEW_THEN_INLINE)
return circuit
def random_rotations_between_grid_interaction_layers_circuit(
qubits: Iterable['cirq.GridQubit'],
depth: int,
*, # forces keyword arguments
two_qubit_op_factory: Callable[
['cirq.GridQubit', 'cirq.GridQubit', 'np.random.RandomState'],
'cirq.OP_TREE'] = lambda a, b, _: ops.CZPowGate()(a, b),
pattern: Sequence[GridInteractionLayer] = GRID_STAGGERED_PATTERN,
single_qubit_gates: Sequence['cirq.Gate'] = (
ops.X**0.5,
ops.Y**0.5,
ops.PhasedXPowGate(phase_exponent=0.25, exponent=0.5),
),
add_final_single_qubit_layer: bool = True,
seed: 'cirq.RANDOM_STATE_OR_SEED_LIKE' = None,
) -> 'cirq.Circuit':
"""Generate a random quantum circuit of a particular form.
This construction is based on the circuits used in the paper
https://www.nature.com/articles/s41586-019-1666-5.
The generated circuit consists of a number of "cycles", this number being
specified by `depth`. Each cycle is actually composed of two sub-layers:
a layer of single-qubit gates followed by a layer of two-qubit gates,
controlled by their respective arguments, see below. The pairs of qubits
in a given entangling layer is controlled by the `pattern` argument,
see below.
Args:
qubits: The qubits to use.
depth: The number of cycles.
two_qubit_op_factory: A callable that returns a two-qubit operation.
These operations will be generated with calls of the form
`two_qubit_op_factory(q0, q1, prng)`, where `prng` is the
pseudorandom number generator.
pattern: A sequence of GridInteractionLayers, each of which determine
which pairs of qubits are entangled. The layers in a pattern are
iterated through sequentially, repeating until `depth` is reached.
single_qubit_gates: Single-qubit gates are selected randomly from this
sequence. No qubit is acted upon by the same single-qubit gate in
consecutive cycles. If only one choice of single-qubit gate is
given, then this constraint is not enforced.
add_final_single_qubit_layer: Whether to include a final layer of
single-qubit gates after the last cycle.
seed: A seed or random state to use for the pseudorandom number
generator.
"""
prng = value.parse_random_state(seed)
qubits = list(qubits)
coupled_qubit_pairs = _coupled_qubit_pairs(qubits)
circuit = circuits.Circuit()
previous_single_qubit_layer = circuits.Moment()
single_qubit_layer_factory = _single_qubit_gates_arg_to_factory(
single_qubit_gates=single_qubit_gates, qubits=qubits, prng=prng)
for i in range(depth):
single_qubit_layer = single_qubit_layer_factory.new_layer(
previous_single_qubit_layer)
circuit += single_qubit_layer
two_qubit_layer = _two_qubit_layer(coupled_qubit_pairs,
two_qubit_op_factory,
pattern[i % len(pattern)], prng)
circuit += two_qubit_layer
previous_single_qubit_layer = single_qubit_layer
if add_final_single_qubit_layer:
circuit += single_qubit_layer_factory.new_layer(
previous_single_qubit_layer)
return circuit
def random_rotations_between_two_qubit_circuit(
q0: 'cirq.Qid',
q1: 'cirq.Qid',
depth: int,
two_qubit_op_factory: Callable[
['cirq.Qid', 'cirq.Qid', 'np.random.RandomState'],
'cirq.OP_TREE'] = lambda a, b, _: ops.CZPowGate()(a, b),
single_qubit_gates: Sequence['cirq.Gate'] = (
ops.X**0.5,
ops.Y**0.5,
ops.PhasedXPowGate(phase_exponent=0.25, exponent=0.5),
),
add_final_single_qubit_layer: bool = True,
seed: 'cirq.RANDOM_STATE_OR_SEED_LIKE' = None,
) -> 'cirq.Circuit':
"""Generate a random two-qubit quantum circuit.
This construction uses a similar structure to those in the paper
https://www.nature.com/articles/s41586-019-1666-5.
The generated circuit consists of a number of "cycles", this number being
specified by `depth`. Each cycle is actually composed of two sub-layers:
a layer of single-qubit gates followed by a layer of two-qubit gates,
controlled by their respective arguments, see below.
Args:
q0: The first qubit
q1: The second qubit
depth: The number of cycles.
two_qubit_op_factory: A callable that returns a two-qubit operation.
These operations will be generated with calls of the form
`two_qubit_op_factory(q0, q1, prng)`, where `prng` is the
pseudorandom number generator.
single_qubit_gates: Single-qubit gates are selected randomly from this
sequence. No qubit is acted upon by the same single-qubit gate in
consecutive cycles. If only one choice of single-qubit gate is
given, then this constraint is not enforced.
add_final_single_qubit_layer: Whether to include a final layer of
single-qubit gates after the last cycle (subject to the same
non-consecutivity constraint).
seed: A seed or random state to use for the pseudorandom number
generator.
"""
prng = value.parse_random_state(seed)
circuit = circuits.Circuit()
previous_single_qubit_layer = circuits.Moment()
single_qubit_layer_factory = _single_qubit_gates_arg_to_factory(
single_qubit_gates=single_qubit_gates, qubits=(q0, q1), prng=prng)
for _ in range(depth):
single_qubit_layer = single_qubit_layer_factory.new_layer(
previous_single_qubit_layer)
circuit += single_qubit_layer
circuit += two_qubit_op_factory(q0, q1, prng)
previous_single_qubit_layer = single_qubit_layer
if add_final_single_qubit_layer:
circuit += single_qubit_layer_factory.new_layer(
previous_single_qubit_layer)
return circuit
def random_one_qubit_gate():
return ops.PhasedXPowGate(phase_exponent=prng.rand(),
exponent=prng.rand())