qiskit.circuit.library.C4XGate¶

class
C4XGate
(label=None, ctrl_state=None)[source]¶ The 4qubit controlled X gate.
This implementation is based on Page 21, Lemma 7.5, of [1], with the use of the relative phase version of c3x, the rc3x [2].
References
[1] Barenco et al., 1995. https://arxiv.org/pdf/quantph/9503016.pdf [2] Maslov, 2015. https://arxiv.org/abs/1508.03273
Create a new 4qubit controlled X gate.
Methods
__init__
([label, ctrl_state])Create a new 4qubit controlled X gate.
add_decomposition
(decomposition)Add a decomposition of the instruction to the SessionEquivalenceLibrary.
assemble
()Assemble a QasmQobjInstruction
broadcast_arguments
(qargs, cargs)Validation and handling of the arguments and its relationship.
c_if
(classical, val)Add classical condition on register classical and value val.
control
([num_ctrl_qubits, label, ctrl_state])Controlled version of this gate.
copy
([name])Copy of the instruction.
inverse
()Invert this gate.
Return True .IFF.
mirror
()DEPRECATED: use instruction.reverse_ops().
power
(exponent)Creates a unitary gate as gate^exponent.
qasm
()Return a default OpenQASM string for the instruction.
repeat
(n)Creates an instruction with gate repeated n amount of times.
For a composite instruction, reverse the order of subinstructions.
soft_compare
(other)Soft comparison between gates.
Return a Numpy.array for the gate unitary matrix.
validate_parameter
(parameter)Gate parameters should be int, float, or ParameterExpression
Attributes
Return the control state of the gate as a decimal integer.
Get the decompositions of the instruction from the SessionEquivalenceLibrary.
Return definition in terms of other basic gates.
Get the duration.
Return gate label
Get name of gate.
Get number of control qubits.
Get parameters from base_gate.
Get the time unit of duration.

add_decomposition
(decomposition)¶ Add a decomposition of the instruction to the SessionEquivalenceLibrary.

assemble
()¶ Assemble a QasmQobjInstruction
 Return type
Instruction

broadcast_arguments
(qargs, cargs)¶ Validation and handling of the arguments and its relationship.
For example,
cx([q[0],q[1]], q[2])
meanscx(q[0], q[2]); cx(q[1], q[2])
. This method yields the arguments in the right grouping. In the given example:in: [[q[0],q[1]], q[2]],[] outs: [q[0], q[2]], [] [q[1], q[2]], []
The general broadcasting rules are:
If len(qargs) == 1:
[q[0], q[1]] > [q[0]],[q[1]]
If len(qargs) == 2:
[[q[0], q[1]], [r[0], r[1]]] > [q[0], r[0]], [q[1], r[1]] [[q[0]], [r[0], r[1]]] > [q[0], r[0]], [q[0], r[1]] [[q[0], q[1]], [r[0]]] > [q[0], r[0]], [q[1], r[0]]
If len(qargs) >= 3:
[q[0], q[1]], [r[0], r[1]], ...] > [q[0], r[0], ...], [q[1], r[1], ...]
 Parameters
qargs (
List
) – List of quantum bit arguments.cargs (
List
) – List of classical bit arguments.
 Return type
Tuple
[List
,List
] Returns
A tuple with single arguments.
 Raises
CircuitError – If the input is not valid. For example, the number of arguments does not match the gate expectation.

c_if
(classical, val)¶ Add classical condition on register classical and value val.

control
(num_ctrl_qubits=1, label=None, ctrl_state=None)[source]¶ Controlled version of this gate.
 Parameters
num_ctrl_qubits (int) – number of control qubits.
label (str or None) – An optional label for the gate [Default: None]
ctrl_state (int or str or None) – control state expressed as integer, string (e.g. ‘110’), or None. If None, use all 1s.
 Returns
controlled version of this gate.
 Return type

copy
(name=None)¶ Copy of the instruction.
 Parameters
name (str) – name to be given to the copied circuit, if None then the name stays the same.
 Returns
 a copy of the current instruction, with the name
updated if it was provided
 Return type

property
ctrl_state
¶ Return the control state of the gate as a decimal integer.
 Return type
int

property
decompositions
¶ Get the decompositions of the instruction from the SessionEquivalenceLibrary.

property
definition
¶ Return definition in terms of other basic gates. If the gate has open controls, as determined from self.ctrl_state, the returned definition is conjugated with X without changing the internal _definition.
 Return type
List

property
duration
¶ Get the duration.

is_parameterized
()¶ Return True .IFF. instruction is parameterized else False

property
label
¶ Return gate label
 Return type
str

mirror
()¶ DEPRECATED: use instruction.reverse_ops().
 Returns
 a new instruction with subinstructions
reversed.
 Return type

property
name
¶ Get name of gate. If the gate has open controls the gate name will become:
<original_name_o<ctrl_state>
where <original_name> is the gate name for the default case of closed control qubits and <ctrl_state> is the integer value of the control state for the gate.
 Return type
str

property
num_ctrl_qubits
¶ Get number of control qubits.
 Returns
The number of control qubits for the gate.
 Return type
int

property
params
¶ Get parameters from base_gate.
 Returns
List of gate parameters.
 Return type
list
 Raises
CircuitError – Controlled gate does not define a base gate

power
(exponent)¶ Creates a unitary gate as gate^exponent.
 Parameters
exponent (float) – Gate^exponent
 Returns
To which to_matrix is self.to_matrix^exponent.
 Return type
 Raises
CircuitError – If Gate is not unitary

qasm
()¶ Return a default OpenQASM string for the instruction.
Derived instructions may override this to print in a different format (e.g. measure q[0] > c[0];).

repeat
(n)¶ Creates an instruction with gate repeated n amount of times.
 Parameters
n (int) – Number of times to repeat the instruction
 Returns
Containing the definition.
 Return type
 Raises
CircuitError – If n < 1.

reverse_ops
()¶ For a composite instruction, reverse the order of subinstructions.
This is done by recursively reversing all subinstructions. It does not invert any gate.
 Returns
 a new instruction with
subinstructions reversed.
 Return type

soft_compare
(other)¶ Soft comparison between gates. Their names, number of qubits, and classical bit numbers must match. The number of parameters must match. Each parameter is compared. If one is a ParameterExpression then it is not taken into account.
 Parameters
other (instruction) – other instruction.
 Returns
are self and other equal up to parameter expressions.
 Return type
bool

to_matrix
()¶ Return a Numpy.array for the gate unitary matrix.
 Returns
if the Gate subclass has a matrix definition.
 Return type
np.ndarray
 Raises
CircuitError – If a Gate subclass does not implement this method an exception will be raised when this base class method is called.

property
unit
¶ Get the time unit of duration.

validate_parameter
(parameter)¶ Gate parameters should be int, float, or ParameterExpression
