Defines the ComputationalBasisPOVM class

Module Contents



A POVM that "measures" states in the computational "Z" basis.

class pygsti.modelmembers.povms.computationalpovm.ComputationalBasisPOVM(nqubits, evotype='default', qubit_filter=None, state_space=None)

Bases: pygsti.modelmembers.povms.povm.POVM

A POVM that “measures” states in the computational “Z” basis.

  • nqubits (int) – The number of qubits

  • evotype (Evotype or str, optional) – The evolution type. The special value “default” is equivalent to specifying the value of pygsti.evotypes.Evotype.default_evotype.

  • qubit_filter (list, optional) – An optional list of integers specifying a subset of the qubits to be measured.

  • state_space (StateSpace, optional) – The state space for this POVM. If None a default state space with the appropriate number of qubits is used.

classmethod from_pure_vectors(cls, pure_vectors, evotype, state_space)
__contains__(self, key)

For lazy creation of effect vectors


Implement iter(self).


Return len(self).


An iterator over the effect (outcome) labels of this POVM.


An iterator over the effect vectors of this POVM.


An iterator over the (effect_label, effect_vector) items in this POVM.

__getitem__(self, key)

For lazy creation of effect vectors


Needed for OrderedDict-derived classes (to set dict items)

simplify_effects(self, prefix='')

Creates a dictionary of simplified effect vectors.

Returns a dictionary of effect POVMEffects that belong to the POVM’s parent Model - that is, whose gpindices are set to all or a subset of this POVM’s gpindices. Such effect vectors are used internally within computations involving the parent Model.


prefix (str) – A string, usually identitying this POVM, which may be used to prefix the simplified gate keys.


OrderedDict of POVMEffects

to_memoized_dict(self, mmg_memo)

Create a serializable dict with references to other objects in the memo.


mmg_memo (dict) – Memo dict from a ModelMemberGraph, i.e. keys are object ids and values are ModelMemberGraphNodes (which contain the serialize_id). This is NOT the same as other memos in ModelMember (e.g. copy, allocate_gpindices, etc.).


mm_dict (dict) – A dict representation of this ModelMember ready for serialization This must have at least the following fields:

module, class, submembers, params, state_space, evotype

Additional fields may be added by derived classes.

classmethod _from_memoized_dict(cls, mm_dict, serial_memo)

For subclasses to implement. Submember-existence checks are performed, and the gpindices of the return value is set, by the non-underscored :method:`from_memoized_dict` implemented in this class.

_is_similar(self, other, rtol, atol)

Returns True if other model member (which it guaranteed to be the same type as self) has the same local structure, i.e., not considering parameter values or submembers


Return str(self).