WeightedAdder
class qiskit.circuit.library.WeightedAdder(num_state_qubits=None, weights=None, name='adder')
Bases: BlueprintCircuit
A circuit to compute the weighted sum of qubit registers.
Given qubit basis states and non-negative integer weights , this circuit performs the operation
where is the number of sum qubits required. This can be computed as
or if the sum of the weights is 0 (then the expression in the logarithm is invalid).
For qubits in a circuit diagram, the first weight applies to the upper-most qubit. For an example where the state of 4 qubits is added into a sum register, the circuit can be schematically drawn as
┌────────┐
state_0: ┤0 ├ | state_0 * weights[0]
│ │ |
state_1: ┤1 ├ | + state_1 * weights[1]
│ │ |
state_2: ┤2 ├ | + state_2 * weights[2]
│ │ |
state_3: ┤3 ├ | + state_3 * weights[3]
│ │
sum_0: ┤4 ├ |
│ Adder │ |
sum_1: ┤5 ├ | = sum_0 * 2^0 + sum_1 * 2^1 + sum_2 * 2^2
│ │ |
sum_2: ┤6 ├ |
│ │
carry_0: ┤7 ├
│ │
carry_1: ┤8 ├
│ │
control_0: ┤9 ├
└────────┘Computes the weighted sum controlled by state qubits.
Parameters
- num_state_qubits (int | None) – The number of state qubits.
- weights (List[int] | None) – List of weights, one for each state qubit. If none are provided they default to 1 for every qubit.
- name (str) – The name of the circuit.
Attributes
ancillas
Returns a list of ancilla bits in the order that the registers were added.
calibrations
Return calibration dictionary.
The custom pulse definition of a given gate is of the form {'gate_name': {(qubits, params): schedule}}
clbits
Returns a list of classical bits in the order that the registers were added.
data
extension_lib
Default value: 'include "qelib1.inc";'
global_phase
Return the global phase of the circuit in radians.
header
Default value: 'OPENQASM 2.0;'
instances
Default value: 127
layout
Return any associated layout information about the circuit
This attribute contains an optional TranspileLayout object. This is typically set on the output from transpile() or PassManager.run() to retain information about the permutations caused on the input circuit by transpilation.
There are two types of permutations caused by the transpile() function, an initial layout which permutes the qubits based on the selected physical qubits on the Target, and a final layout which is an output permutation caused by SwapGates inserted during routing.
metadata
The user provided metadata associated with the circuit.
The metadata for the circuit is a user provided dict of metadata for the circuit. It will not be used to influence the execution or operation of the circuit, but it is expected to be passed between all transforms of the circuit (ie transpilation) and that providers will associate any circuit metadata with the results it returns from execution of that circuit.
num_ancillas
Return the number of ancilla qubits.
num_carry_qubits
The number of carry qubits required to compute the sum.
Note that this is not necessarily equal to the number of ancilla qubits, these can be queried using num_ancilla_qubits.
Returns
The number of carry qubits required to compute the sum.
num_clbits
Return number of classical bits.
num_control_qubits
The number of additional control qubits required.
Note that the total number of ancilla qubits can be obtained by calling the method num_ancilla_qubits.
Returns
The number of additional control qubits required (0 or 1).
num_parameters
num_qubits
Return number of qubits.
num_state_qubits
The number of qubits to be summed.
Returns
The number of state qubits.
num_sum_qubits
The number of sum qubits in the circuit.
Returns
The number of qubits needed to represent the weighted sum of the qubits.
op_start_times
Return a list of operation start times.
This attribute is enabled once one of scheduling analysis passes runs on the quantum circuit.
Returns
List of integers representing instruction start times. The index corresponds to the index of instruction in QuantumCircuit.data.
Raises
AttributeError – When circuit is not scheduled.
parameters
prefix
Default value: 'circuit'
qregs
Type: list[QuantumRegister]
A list of the quantum registers associated with the circuit.
qubits
Returns a list of quantum bits in the order that the registers were added.
weights
The weights for the qubit states.
Returns
The weight for the qubit states.