RZXGate
RZXGate(theta)
A parameteric 2-qubit interaction (rotation about ZX).
This gate is maximally entangling at .
The cross-resonance gate (CR) for superconducting qubits implements a ZX interaction (however other terms are also present in an experiment).
Circuit Symbol:
┌─────────┐
q_0: ┤0 ├
│ Rzx(θ) │
q_1: ┤1 ├
└─────────┘
Matrix Representation:
In Qiskit’s convention, higher qubit indices are more significant (little endian convention). In the above example we apply the gate on (q_0, q_1) which results in the tensor order. Instead, if we apply it on (q_1, q_0), the matrix will be :
┌─────────┐
q_0: ┤1 ├
│ Rzx(θ) │
q_1: ┤0 ├
└─────────┘
This is a direct sum of RX rotations, so this gate is equivalent to a uniformly controlled (multiplexed) RX gate:
Examples:
Create new RZX gate.
Attributes
decompositions
Get the decompositions of the instruction from the SessionEquivalenceLibrary.
definition
Return definition in terms of other basic gates.
label
str
Return gate label
Return type
str
params
return instruction params.
Methods
add_decomposition
RZXGate.add_decomposition(decomposition)
Add a decomposition of the instruction to the SessionEquivalenceLibrary.
assemble
RZXGate.assemble()
broadcast_arguments
RZXGate.broadcast_arguments(qargs, cargs)
Validation and handling of the arguments and its relationship.
For example, cx([q[0],q[1]], q[2])
means cx(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
RZXGate.c_if(classical, val)
Add classical condition on register classical and value val.
control
RZXGate.control(num_ctrl_qubits=1, label=None, ctrl_state=None)
Return controlled version of gate. See ControlledGate
for usage.
Parameters
- num_ctrl_qubits (
Optional
[int
]) – number of controls to add to gate (default=1) - label (
Optional
[str
]) – optional gate label - ctrl_state (
Union
[int
,str
,None
]) – The control state in decimal or as a bitstring (e.g. ‘111’). If None, use 2**num_ctrl_qubits-1.
Returns
Controlled version of gate. This default algorithm uses num_ctrl_qubits-1 ancillae qubits so returns a gate of size num_qubits + 2*num_ctrl_qubits - 1.
Return type
Raises
QiskitError – unrecognized mode or invalid ctrl_state
copy
RZXGate.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
inverse
RZXGate.inverse()
Return inverse RZX gate (i.e. with the negative rotation angle).
is_parameterized
RZXGate.is_parameterized()
Return True .IFF. instruction is parameterized else False
mirror
RZXGate.mirror()
For a composite instruction, reverse the order of sub-gates.
This is done by recursively mirroring all sub-instructions. It does not invert any gate.
Returns
a fresh gate with sub-gates reversed
Return type
power
RZXGate.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
RZXGate.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
RZXGate.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.
to_matrix
RZXGate.to_matrix()
Return a Numpy.array for the gate unitary matrix.
Raises
CircuitError – If a Gate subclass does not implement this method an exception will be raised when this base class method is called.
Return type
ndarray