pygsti.extras.rb.simulate
¶
Clifford circuits with Pauli errors simulation functions
Module Contents¶
Classes¶
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Functions¶
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A Clifford circuit simulator for an error model whereby each gate in the circuit induces independent Pauli 

Generates a single measurement result for the circuit_simulator_for_tensored_independent_pauli_errors() 

Simulates RB with Pauli errors. Can be used to simulated Clifford RB, direct RB and mirror RB. This 

Returns a dictionary encoding a Paulistochastic error model whereby the errors are the same on all the 

Returns a dictionary encoding a Paulistochastic error model whereby the errors are independent of the gates, 

Returns a dictionary encoding a Paulistochastic error model whereby the errors caused by a gate act 
Attributes¶
 pygsti.extras.rb.simulate._samp¶
 pygsti.extras.rb.simulate.random_paulierror_in_chp(q)¶
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 pygsti.extras.rb.simulate.random_pauli_in_chp(q)¶
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 pygsti.extras.rb.simulate.stdgate_to_chp(gate, chpqubits)¶
todo Converts any of the standard Clifford gates to a chp string.
 class pygsti.extras.rb.simulate.IndDepolErrorModel(gate_errors, readout_errors)¶
Bases:
object
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 layer_uniform_pauli_probability(self, layer, qubitorder)¶
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 readout_uniform_pauli_probability(self, qubitorder)¶
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 pygsti.extras.rb.simulate.depolarizing_errors_circuit_simulator(circuitlist, shots, errormodel, gate_to_chp=None, aux_info_list=None, collision_action='keepseparate', outdir='', perge_chp_files=True, returnds=True, verbosity=1)¶
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 pygsti.extras.rb.simulate.circuit_simulator_for_tensored_independent_pauli_errors(circuit, pspec, errormodel, counts, alloutcomes=False, idle1q_placeholder='I')¶
A Clifford circuit simulator for an error model whereby each gate in the circuit induces independent Pauli errors on some or all of the qubits, with userspecified error probabilities that can vary between gate and between Pauli. State preparation and measurements errors are restricted to bitflip errors on the output.
This simulator is a stochasticunravelling simulator that uses an efficientinqubitnumber representation of the action of Clifford gates on Paulis. Specifically, it samples Pauli errors according to the error statistics provided, and propogates them through the layers of Clifford gates in the circuit using the conjugation action of the Cliffords on Paulis (as represented by 2n X 2n symplectic matrices for n qubits). This is repeated for the number of counts (counts) requested. So, this function takes a time to run that scales as (counts * n^2 * circuit depth). Therefore, this method will be slower than the pyGSTi densitymatrix simulators at low qubit number and high counts.
 Parameters
circuit (Circuit) – The circuit to simulate. It should only contain gates that are also contained within the provided QubitProcessorSpec pspec and are Clifford gates.
pspec (QubitProcessorSpec) – The QubitProcessorSpec that defines the device. The Clifford model in QubitProcessorSpec should contain all of the gates that are in the circuit.
errormodel (dict) –
A dictionary defining the error model. This errormodel should have keys that are Label objects (the elements of the circuit). The values for a particular Label is an (n,4) numpy array of floats, that encodes the errors caused by the gate specified by that Label. The (i,j) value in the array is the probability that this gate is followed by Pauli i where Pauli 0 = identity, Pauli 1 = X, Pauli 2 = Y and Pauli 3 = Z. So, if the arrray is [1.,0.,0.,0.] in every row then there is no errors, if it is [1p,p/3,p/3,p/3] in row j then there is equal probability of each Pauli error on qubit j with an error probability of p.
Some simple error models can be autoconstructed using create_locally_gate_independent_pauli_error_model() or create_iid_pauli_error_model()`.
counts (The number of counts, i.e., the number of repeats of the circuit that data should be generated for.) –
alloutcomes (bool, optional) – If True then a dictionary is returned where the keys are all possible outcomes (i.e., all length n bit strings) and the values are the counts for all of the outcomes. If False, then the returned dictionary only contains keys for those outcomes that happen at least once.
TODO (docstring: idle1q_placeholder) –
 Returns
dict – A dictionary of simulated measurement outcome counts.
 pygsti.extras.rb.simulate.oneshot_circuit_simulator_for_tensored_independent_pauli_errors(circuit, pspec, errormodel, idle1q_placeholder='I')¶
Generates a single measurement result for the circuit_simulator_for_tensored_independent_pauli_errors() simulator
 Parameters
circuit (Circuit) – The circuit to simulate. It should only contain gates that are also contained within the provided QubitProcessorSpec pspec and are Clifford gates.
pspec (QubitProcessorSpec) – The QubitProcessorSpec that defines the device. The Clifford model in QubitProcessorSpec should contain all of the gates that are in the circuit.
errormodel (dict) – A dictionary defining the error model. This errormodel should have keys that are Label objects (the elements of the circuit). The values for a particular Label is an (n,4) numpy array of floats, that encodes the errors caused by the gate specified by that Label. The (i,j) value in the array is the probability that this gate is followed by Pauli i where Pauli 0 = identity, Pauli 1 = X, Pauli 2 = Y and Pauli 3 = Z. So, if the arrray is [1.,0.,0.,0.] in every row then there is no errors, if it is [1p,p/3,p/3,p/3] in row j then there is equal probability of each Pauli error on qubit j with an error probability of p.
TODO (docstring: idle1q_placeholder) –
 Returns
tuple – A tuple of values that are 0 or 1, corresponding to the results of a zmeasurement on all the qubits. The ordering of this tuple corresponds to the ordering of the wires in the circuit.
 pygsti.extras.rb.simulate.rb_with_pauli_errors(pspec, errormodel, lengths, k, counts, qubit_subset=None, filename=None, rbtype='DRB', rbspec=[], returndata=True, appenddata=False, verbosity=0, idle1q_placeholder='I')¶
Simulates RB with Pauli errors. Can be used to simulated Clifford RB, direct RB and mirror RB. This function:
Samples RB circuits
Simulates the RB circuit with the specified Paulierrors error model
Records the summary RB data to file and/or returns this RB data.
Step 1 is implemented using the inbuilt RB samplers. For more information see rb.sample. Step 2 is implemented using the circuit_simulator_for_tensored_independent_pauli_errors() stochastic errors circuit simulator. See that function for more details.
 Parameters
pspec (QubitProcessorSpec) – The QubitProcessorSpec that defines the device.
errormodel (dict) –
A dictionary defining the error model. This errormodel should have keys that are Label objects corresponding to the gates in pspec. The values for a particular Label is an (n,4) numpy array of floats, that encodes the errors caused by the gate specified by that Label. The (i,j) value in the array is the probability that this gate is followed by Pauli i where Pauli 0 = identity, Pauli 1 = X, Pauli 2 = Y and Pauli 3 = Z. So, if the arrray is [1.,0.,0.,0.] in every row then there is no errors, if it is [1p,p/3,p/3,p/3] in row j then there is equal probability of each Pauli error on qubit j with an error probability of p.
Some simple error models can be autoconstructed using create_locally_gate_independent_pauli_error_model() or create_iid_pauli_error_model()`.
lengths (list) – A list of the RB lengths to sample and simulate circuits at. E.g., for Clifford RB this is the number of Cliffords in the uncompiled circuit  2 (see rb.sample.clifford_rb_circuit()).
k (int) – The number of circuits to sample and simulate at each RB length.
counts (int) – The number of counts for each circuit.
qubit_subset (list) – If not None, a list of qubit labels that the RB experiment should be over, that is a subset of the qubits in pspec.
filename (str, optional) – A filename for where to save the data (if None, the data is not saved to file).
rbtype ({'DRB', 'CRB', 'MRB'}) – The RB type to simulate. ‘DRB’ corresponds to direct RB, ‘CRB’ corresponds to Clifford RB, and ‘MRB’ corresponds to mirror RB.
rbspec (list, optional) – Handed to the RB sampling function for all arguments after pspec and the RB lengths, which are the first two arguments handed to the relevant function. See the relevant RB circuit sampling functions for details.
returndata (bool, optional) – Whether to return the data
appenddata (bool, optional) – If writing to file (i.e., filename is not None), whether to append the data to an already existing file or to write over any existing file.
verbosity (int, optional) – The amount of printtoscreen.
 Returns
None or RBSummaryDataset – If returndata an RBSummaryDataset containing the results. Else, None
 pygsti.extras.rb.simulate.create_iid_pauli_error_model(pspec, one_qubit_gate_errorrate, two_qubit_gate_errorrate, idle_errorrate, measurement_errorrate=0.0, ptype='uniform', idle1q_placeholder='I')¶
Returns a dictionary encoding a Paulistochastic error model whereby the errors are the same on all the 1qubit gates, and the same on all 2qubit gates. The probability of the 3 different Pauli errors on each qubit is specified by ptype and can either be uniform, or always X, Y, or Z errors.
The dictionary returned is in the appropriate format for the circuit_simulator_for_tensored_independent_pauli_errors() circuit simulator function.
 Parameters
pspec (QubitProcessorSpec) – The QubitProcessorSpec that defines the device.
one_qubit_gate_errorrate (float) – The 1qubit gates error rate (the probability of a Pauli error on the target qubit) not including idle gates.
two_qubit_gate_errorrate (float) – The 2qubit gates error rate (the total probability of a Pauli error on either qubit the gate acts on – each qubit has independent errors with equal probabilities).
idle_errorrate (float) – The idle gates error rate.
measurement_errorrate (flip) – The measurement error rate for all of the qubits. This is the probability that a qubits measurement result is bitflipped.
ptype (str, optional) – Can be ‘uniform’, ‘X’, ‘Y’ or ‘Z’. If ‘uniform’ then 3 Pauli errors are equally likely, if ‘X’, ‘Y’ or ‘Z’ then the errors are always Pauli X, Y or Z errors, respectively.
TODO (docstring idle1q_placeholder) –
 Returns
dict – An dict that encodes the error model described above in the format required for the simulator circuit_simulator_for_tensored_independent_pauli_errors().
 pygsti.extras.rb.simulate.create_locally_gate_independent_pauli_error_model(pspec, gate_errorrate_dict, measurement_errorrate_dict={}, ptype='uniform', idle1q_placeholder='I')¶
Returns a dictionary encoding a Paulistochastic error model whereby the errors are independent of the gates, with a qubit subject to an error after a circuit layer with the probabilities specified by the dict gate_errorrate_dict. The probability of the 3 different Pauli errors on each qubit is specified by ptype and can either be uniform, or always X, Y, or Z errors.
The dictionary returned is in the appropriate format for the circuit_simulator_for_tensored_independent_pauli_errors() circuit simulator function.
 Parameters
pspec (QubitProcessorSpec) – The QubitProcessorSpec that defines the device.
gate_errorrate_dict (dict) – A dict where the keys are elements of pspec.qubit_labels and the values are floats in [0,1]. The element for qubit with label q is the error probability for that qubit.
measurement_errorrate_dict (dict) – A dict where the keys are elements of pspec.qubit_labels and the values are floats in [0,1]. The element for qubit with label q is the measurement bitflip error probability for that qubit. All qubits that do not have a measurement error rate specified are assumed to have perfect measurements.
ptype (str, optional) – Can be ‘uniform’, ‘X’, ‘Y’ or ‘Z’. If ‘uniform’ then 3 Pauli errors are equally likely, if ‘X’, ‘Y’ or ‘Z’ then the errors are always Pauli X, Y or Z errors, respectively.
TODO (docstring: idle1q_placeholder) –
 Returns
dict – An dict that encodes the error model described above in the format required for the simulator circuit_simulator_for_tensored_independent_pauli_errors().
 pygsti.extras.rb.simulate.create_local_pauli_error_model(pspec, one_qubit_gate_errorrate_dict, two_qubit_gate_errorrate_dict, measurement_errorrate_dict={}, ptype='uniform')¶
Returns a dictionary encoding a Paulistochastic error model whereby the errors caused by a gate act only on the “target” qubits of the gate, all the 1qubit gates on a qubit have the same error rate, and all the 2qubit gates on a qubit have the same error rate. The probability of the 3 different Pauli errors on each qubit is specified by ptype and can either be uniform, or always X, Y, or Z errors.
The dictionary returned is in the appropriate format for the circuit_simulator_for_tensored_independent_pauli_errors() circuit simulator function.
 Parameters
pspec (QubitProcessorSpec) – The QubitProcessorSpec that defines the device.
one_qubit_gate_errorrate_dict (dict) – A dict where the keys are elements of pspec.qubit_labels and the values are floats in [0,1]. The element for qubit with label q is the error probability for all 1qubit gates on that qubit
two_qubit_gate_errorrate_dict (dict) – A dict where the keys are 2qubit gates in pspec and the values are floats in [0,1]. This is the error probability for the 2qubit gate, split evenly into independent Pauli errors on each of the qubits the gate is intended to act on.
measurement_errorrate_dict (dict) – A dict where the keys are elements of pspec.qubit_labels and the values are floats in [0,1]. The element for qubit with label q is the measurement bitflip error probability for that qubit. All qubits that do not have a measurement error rate specified are assumed to have perfect measurements.
 ptypestr, optional
Can be ‘uniform’, ‘X’, ‘Y’ or ‘Z’. If ‘uniform’ then 3 Pauli errors are equally likely, if ‘X’, ‘Y’ or ‘Z’ then the errors are always Pauli X, Y or Z errors, respectively.
 Returns
dict – An dict that encodes the error model described above in the format required for the simulator circuit_simulator_for_tensored_independent_pauli_errors().