pygsti.modelmembers.instruments.tpinstrumentop

The TPInstrumentOp class and supporting functionality.

Module Contents

Classes

TPInstrumentOp

An element of a TPInstrument.

class pygsti.modelmembers.instruments.tpinstrumentop.TPInstrumentOp(param_ops, index, basis=None)

Bases: pygsti.modelmembers.operations.DenseOperator

An element of a TPInstrument.

A partial implementation of LinearOperator which encapsulates an element of a TPInstrument. Instances rely on their parent being a TPInstrument.

Parameters

param_opslist of LinearOperator objects

A list of the underlying operation objects which constitute a simple parameterization of a TPInstrument. Namely, this is the list of [MT,D1,D2,…Dn] operations which parameterize all of the TPInstrument’s elements.

indexint

The index indicating which element of the TPInstrument the constructed object is. Must be in the range [0,len(param_ops)-1].

basisBasis or {‘pp’,’gm’,’std’} or None

The basis used to construct the Hilbert-Schmidt space representation of this state as a super-operator. If None, certain functionality, such as access to Kraus operators, will be unavailable.

Initialize a new LinearOperator

property num_params

Get the number of independent parameters which specify this operation.

Returns
int

the number of independent parameters.

submembers()

Get the ModelMember-derived objects contained in this one.

Returns

list

to_memoized_dict(mmg_memo)

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

Parameters
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.).

Returns
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.

deriv_wrt_params(wrt_filter=None)

The element-wise derivative this operation.

Construct a matrix whose columns are the vectorized derivatives of the flattened operation matrix with respect to a single operation parameter. Thus, each column is of length op_dim^2 and there is one column per operation parameter. An empty 2D array in the StaticArbitraryOp case (num_params == 0).

Parameters
wrt_filterlist or numpy.ndarray

List of parameter indices to take derivative with respect to. (None means to use all the this operation’s parameters.)

Returns
numpy array

Array of derivatives with shape (dimension^2, num_params)

has_nonzero_hessian()

Whether this operation has a non-zero Hessian with respect to its parameters.

(i.e. whether it only depends linearly on its parameters or not)

Returns

bool

to_vector()

Get the operation parameters as an array of values.

Returns
numpy array

The operation parameters as a 1D array with length num_params().

from_vector(v, close=False, dirty_value=True)

Initialize the operation using a vector of parameters.

Parameters
vnumpy array

The 1D vector of operation parameters. Length must == num_params()

closebool, optional

Whether v is close to this operation’s current set of parameters. Under some circumstances, when this is true this call can be completed more quickly.

dirty_valuebool, optional

The value to set this object’s “dirty flag” to before exiting this call. This is passed as an argument so it can be updated recursively. Leave this set to True unless you know what you’re doing.

Returns

None