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
A list of AncillaQubit
s in the order that they were added. You should not mutate this.
calibrations
Return calibration dictionary.
The custom pulse definition of a given gate is of the form {'gate_name': {(qubits, params): schedule}}
clbits
A list of Clbit
s in the order that they were added. You should not mutate this.
data
global_phase
The global phase of the current circuit scope in radians.
instances
Default value: 160
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 SwapGate
s inserted during routing.
metadata
Arbitrary user-defined metadata for the circuit.
Qiskit will not examine the content of this mapping, but it will pass it through the transpiler and reattach it to the output, so you can track your own metadata.
num_ancillas
Return the number of ancilla qubits.
num_captured_vars
The number of real-time classical variables in the circuit marked as captured from an enclosing scope.
This is the length of the iter_captured_vars()
iterable. If this is non-zero, num_input_vars
must be zero.
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_declared_vars
The number of real-time classical variables in the circuit that are declared by this circuit scope, excluding inputs or captures.
This is the length of the iter_declared_vars()
iterable.
num_input_vars
The number of real-time classical variables in the circuit marked as circuit inputs.
This is the length of the iter_input_vars()
iterable. If this is non-zero, num_captured_vars
must be zero.
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.
num_vars
The number of real-time classical variables in the circuit.
This is the length of the iter_vars()
iterable.
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 QuantumRegister
s in this circuit. You should not mutate this.
qubits
A list of Qubit
s in the order that they were added. You should not mutate this.
weights
The weights for the qubit states.
Returns
The weight for the qubit states.
name
Type: str
A human-readable name for the circuit.
cregs
Type: list[ClassicalRegister]
A list of the ClassicalRegister
s in this circuit. You should not mutate this.
duration
Type: int | float | None
The total duration of the circuit, set by a scheduling transpiler pass. Its unit is specified by unit
.
unit
The unit that duration
is specified in.