def from_clifford(cliff_in):
"""
Tests an input Clifford ``cliff_in`` to determine if it is, in
fact, a Pauli. If so, it outputs the Pauli. If not, it
raises an error.
:arg cliff_in: Representation of Clifford operator to be converted,
if possible.
:rtype: :class:`qecc.Pauli`
Example:
>>> import qecc as q
>>> cliff = q.Clifford([q.Pauli('XI',2),q.Pauli('IX')], map(q.Pauli,['ZI','IZ']))
>>> q.Pauli.from_clifford(cliff)
i^0 ZI
Converting a Pauli into a Clifford and back again will erase
the phase:
>>> import qecc as q
>>> paul = q.Pauli('YZ',3)
>>> cliff = paul.as_clifford()
>>> q.Pauli.from_clifford(cliff)
i^0 YZ
"""
nq = len(cliff_in.xout) #Determine number of qubits.
test_ex, test_zed = elem_gens(nq) #Get paulis to compare.
"""If the Paulis input to the Clifford are only altered in phase, then the Clifford is also a Pauli."""
for ex_clif, zed_clif, ex_test, zed_test in zip(
cliff_in.xout, cliff_in.zout, test_ex, test_zed):
if ex_clif.op != ex_test.op or zed_clif.op != zed_test.op:
raise ValueError("Clifford is not Pauli.")
#If the Clifford is Pauli, determine which by examining operators with altered phases.
exact = eye_p(nq)
zedact = eye_p(nq) #Initialize accumulators
"""If a negative sign appears on a given generator, assign a Pauli to that qubit that conjugates the generator to a minus sign, e.g. ZXZ = -X """
for idx_x in range(nq):
if cliff_in.xout[idx_x].ph == 2:
exact.op = cc.replace_one_character(exact.op, idx_x, 'Z')
for idx_z in range(nq):
if cliff_in.zout[idx_z].ph == 2:
zedact.op = cc.replace_one_character(zedact.op, idx_z, 'X')
return Pauli((exact * zedact).op)
def from_clifford(cliff_in):
"""
Tests an input Clifford ``cliff_in`` to determine if it is, in
fact, a Pauli. If so, it outputs the Pauli. If not, it
raises an error.
:arg cliff_in: Representation of Clifford operator to be converted,
if possible.
:rtype: :class:`qecc.Pauli`
Example:
>>> import qecc as q
>>> cliff = q.Clifford([q.Pauli('XI',2),q.Pauli('IX')], map(q.Pauli,['ZI','IZ']))
>>> q.Pauli.from_clifford(cliff)
i^0 ZI
Converting a Pauli into a Clifford and back again will erase
the phase:
>>> import qecc as q
>>> paul = q.Pauli('YZ',3)
>>> cliff = paul.as_clifford()
>>> q.Pauli.from_clifford(cliff)
i^0 YZ
"""
nq=len(cliff_in.xout) #Determine number of qubits.
test_ex,test_zed=elem_gens(nq) #Get paulis to compare.
"""If the Paulis input to the Clifford are only altered in phase, then the Clifford is also a Pauli."""
for ex_clif,zed_clif,ex_test,zed_test in zip(cliff_in.xout, cliff_in.zout,test_ex,test_zed):
if ex_clif.op != ex_test.op or zed_clif.op != zed_test.op:
raise ValueError("Clifford is not Pauli.")
#If the Clifford is Pauli, determine which by examining operators with altered phases.
exact=eye_p(nq)
zedact=eye_p(nq) #Initialize accumulators
"""If a negative sign appears on a given generator, assign a Pauli to that qubit that conjugates the generator to a minus sign, e.g. ZXZ = -X """
for idx_x in range(nq):
if cliff_in.xout[idx_x].ph==2:
exact.op = cc.replace_one_character(exact.op, idx_x, 'Z')
for idx_z in range(nq):
if cliff_in.zout[idx_z].ph==2:
zedact.op = cc.replace_one_character(zedact.op, idx_z, 'X')
return Pauli((exact*zedact).op)
def embed(pauli,qubits_tpl,nq):
"""
Takes a Pauli, defined on as many qubits as are in qubits_tpl, and acts it
on the register specified by qubits_tpl, within a register nq long.
"""
new_pauli_op='I'*nq
new_pauli_ph=pauli.ph
for idx in range(len(qubits_tpl)):
new_pauli_op = cc.replace_one_character(new_pauli_op, qubits_tpl[idx], pauli.op[idx])
return Pauli(new_pauli_op,new_pauli_ph)
def embed(pauli,qubits_tpl,nq):
"""
Takes a Pauli, defined on as many qubits as are in qubits_tpl, and acts it
on the register specified by qubits_tpl, within a register nq long.
"""
new_pauli_op='I'*nq
new_pauli_ph=pauli.ph
for idx in range(len(qubits_tpl)):
new_pauli_op = cc.replace_one_character(new_pauli_op, qubits_tpl[idx], pauli.op[idx])
return Pauli(new_pauli_op,new_pauli_ph)
