def grad(objective: typing.Union[Objective, VectorObjective],
variable: Variable = None,
no_compile=False,
*args,
**kwargs):
'''
wrapper function for getting the gradients of Objectives,ExpectationValues, Unitaries (including single gates), and Transforms.
:param obj (QCircuit,ParametrizedGateImpl,Objective,ExpectationValue,Transform,Variable): structure to be differentiated
:param variables (list of Variable): parameter with respect to which obj should be differentiated.
default None: total gradient.
return: dictionary of Objectives, if called on gate, circuit, exp.value, or objective; if Variable or Transform, returns number.
'''
if variable is None:
# None means that all components are created
variables = objective.extract_variables()
result = {}
if len(variables) == 0:
raise TequilaException(
"Error in gradient: Objective has no variables")
for k in variables:
assert (k is not None)
result[k] = grad(objective, k, no_compile=no_compile)
return result
else:
variable = assign_variable(variable)
if no_compile:
compiled = objective
else:
compiler = Compiler(multitarget=True,
trotterized=True,
hadamard_power=True,
power=True,
controlled_phase=True,
controlled_rotation=True,
gradient_mode=True)
compiled = compiler(objective, variables=[variable])
if variable not in compiled.extract_variables():
raise TequilaException(
"Error in taking gradient. Objective does not depend on variable {} "
.format(variable))
if isinstance(objective, ExpectationValueImpl):
return __grad_expectationvalue(E=objective, variable=variable)
elif objective.is_expectationvalue():
return __grad_expectationvalue(E=compiled.args[-1], variable=variable)
elif isinstance(compiled, Objective) or isinstance(compiled,
VectorObjective):
return __grad_objective(objective=compiled, variable=variable)
else:
raise TequilaException(
"Gradient not implemented for other types than ExpectationValue and Objective."
)
def export_to(circuit: QCircuit,
filename: str,
always_use_generators: bool = True,
decompose_control_generators: bool = False,
group_together: bool = False,
qubit_names: list = None, *args, **kwargs):
"""
Parameters
----------
circuit:
the tequila circuit to export
filename:
filename.filetype, e.g. my_circuit.pdf, my_circuit.png (everything that qpic supports)
always_use_generators:
represent all gates with their generators
decompose_control_generators:
Decompose the controls to generators. Effective only in combination with always_use_generators=True.
group_together:
Keep PauliStrings from the same generator together. Effective only in combination with always_use_generators=True.
possible values: False, True, 'TOUCH' and 'BARRIER'. True is the same as TOUCH.
BARRIER will create a visible barrier in qpic
args
kwargs
Returns
-------
"""
if not system_has_qpic:
raise Exception("You need qpic in order to export circuits to pictures ---\n pip install qpic")
if "." not in filename:
raise Exception("export_to: No filetype given {}, expected something like {}.pdf".format(filename, filename))
filename_tmp = filename.split(".")
ftype = filename_tmp[-1]
fname = "".join(filename_tmp[:-1])
if len(filename_tmp) == 1:
ftype = ".pdf"
fname = filename
compiled = Compiler(trotterized=True)(circuit)
export_to_qpic(circuit=compiled,
filename=fname,
always_use_generators=always_use_generators,
decompose_control_generators=decompose_control_generators,
group_together=group_together,
qubit_names=qubit_names, *args, **kwargs)
if ftype != "qpic":
subprocess.call(["qpic", "{}.qpic".format(fname), "-f", ftype])
def convert_to_open_qasm_2(circuit: QCircuit,
variables=None,
zx_calculus: bool = False) -> str:
"""
Allow export to OpenQASM version 2.0
Args:
circuit: to be exported to OpenQASM
variables: optional dictionary with values for variables
zx_calculus: indicate if y-gates must be transformed to xz equivalents
Returns:
str: OpenQASM string
"""
if variables is None and not (len(circuit.extract_variables()) == 0):
raise TequilaException(
"You called export_open_qasm for a parametrized type but forgot to pass down the variables: {}"
.format(circuit.extract_variables()))
compiler = Compiler(multitarget=True,
multicontrol=False,
trotterized=True,
generalized_rotation=True,
exponential_pauli=True,
controlled_exponential_pauli=True,
hadamard_power=True,
controlled_power=True,
power=True,
toffoli=True,
controlled_phase=True,
phase=True,
phase_to_z=True,
controlled_rotation=True,
swap=True,
cc_max=True,
gradient_mode=False,
ry_gate=zx_calculus,
y_gate=zx_calculus,
ch_gate=zx_calculus)
compiled = compiler(circuit, variables=None)
result = "OPENQASM 2.0;\ninclude \"qelib1.inc\";\n"
qubits_names: Dict[int, str] = {}
for q in compiled.qubits:
name = "q[" + str(q) + "]"
qubits_names[q] = name
result += "qreg q[" + str(compiled.n_qubits) + "];\n"
result += "creg c[" + str(compiled.n_qubits) + "];\n"
for g in compiled.gates:
control_str = ''
if g.is_controlled():
if len(g.control) > 2:
raise TequilaException(
"Multi-controls beyond 2 not yet supported for OpenQASM 2.0. Gate was:\n{}"
.format(g))
controls = list(map(lambda c: qubits_names[c], g.control))
control_str = ','.join(controls) + ','
gate_name = name_and_params(g, variables)
for t in g.target:
result += gate_name
result += control_str
result += qubits_names[t]
result += ";\n"
return result