# XXPlusYYGate

qiskit.circuit.library.XXPlusYYGate(theta, beta=0, label='(XX+YY)', *, duration=None, unit='dt')

Bases: Gate

XX+YY interaction gate.

A 2-qubit parameterized XX+YY interaction, also known as an XY gate. Its action is to induce a coherent rotation by some angle between $|01\rangle$ and $|10\rangle$.

Circuit Symbol:

     ┌───────────────┐
q_0: ┤0              ├
│  (XX+YY)(θ,β) │
q_1: ┤1              ├
└───────────────┘

Matrix Representation:

\begin{align}\begin{aligned}\newcommand{\th}{\frac{\theta}{2}}\\\begin{split}R_{XX+YY}(\theta, \beta)\ q_0, q_1 = RZ_0(-\beta) \cdot \exp\left(-i \frac{\theta}{2} \frac{XX+YY}{2}\right) \cdot RZ_0(\beta) = \begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & \cos\left(\th\right) & -i\sin\left(\th\right)e^{-i\beta} & 0 \\ 0 & -i\sin\left(\th\right)e^{i\beta} & \cos\left(\th\right) & 0 \\ 0 & 0 & 0 & 1 \end{pmatrix}\end{split}\end{aligned}\end{align}
Note

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 adding the (optional) phase defined by $beta$ on q_0. Instead, if we apply it on (q_1, q_0), the phase is added on q_1. If $beta$ is set to its default value of $0$, the gate is equivalent in big and little endian.

     ┌───────────────┐
q_0: ┤1              ├
│  (XX+YY)(θ,β) │
q_1: ┤0              ├
└───────────────┘
\begin{align}\begin{aligned}\newcommand{\th}{\frac{\theta}{2}}\\\begin{split}R_{XX+YY}(\theta, \beta)\ q_0, q_1 = RZ_1(-\beta) \cdot \exp\left(-i \frac{\theta}{2} \frac{XX+YY}{2}\right) \cdot RZ_1(\beta) = \begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & \cos\left(\th\right) & -i\sin\left(\th\right)e^{i\beta} & 0 \\ 0 & -i\sin\left(\th\right)e^{-i\beta} & \cos\left(\th\right) & 0 \\ 0 & 0 & 0 & 1 \end{pmatrix}\end{split}\end{aligned}\end{align}

Create new XX+YY gate.

Parameters

## Attributes

### base_class

Get the base class of this instruction. This is guaranteed to be in the inheritance tree of self.

The “base class” of an instruction is the lowest class in its inheritance tree that the object should be considered entirely compatible with for _all_ circuit applications. This typically means that the subclass is defined purely to offer some sort of programmer convenience over the base class, and the base class is the “true” class for a behavioural perspective. In particular, you should not override base_class if you are defining a custom version of an instruction that will be implemented differently by hardware, such as an alternative measurement strategy, or a version of a parametrised gate with a particular set of parameters for the purposes of distinguishing it in a Target from the full parametrised gate.

This is often exactly equivalent to type(obj), except in the case of singleton instances of standard-library instructions. These singleton instances are special subclasses of their base class, and this property will return that base. For example:

>>> isinstance(XGate(), XGate)
True
>>> type(XGate()) is XGate
False
>>> XGate().base_class is XGate
True

In general, you should not rely on the precise class of an instruction; within a given circuit, it is expected that Instruction.name should be a more suitable discriminator in most situations.

### condition

The classical condition on the instruction.

### condition_bits

Get Clbits in condition.

### decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

### definition

Return definition in terms of other basic gates.

### duration

Get the duration.

### label

Return instruction label

### mutable

Is this instance is a mutable unique instance or not.

If this attribute is False the gate instance is a shared singleton and is not mutable.

Return the name.

### num_clbits

Return the number of clbits.

### num_qubits

Return the number of qubits.

### params

return instruction params.

### unit

Get the time unit of duration.

## Methods

### inverse

inverse()

Return inverse XX+YY gate (i.e. with the negative rotation angle and same phase angle).

### power

power(exponent)

Raise gate to a power.