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ECRGate

class qiskit.circuit.library.ECRGate

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Bases: Gate

An echoed cross-resonance gate.

This gate is maximally entangling and is equivalent to a CNOT up to single-qubit pre-rotations. The echoing procedure mitigates some unwanted terms (terms other than ZX) to cancel in an experiment. More specifically, this gate implements 12(IX−XY)\frac{1}{\sqrt{2}}(IX-XY).

Can be applied to a QuantumCircuit with the ecr() method.

Circuit Symbol:

     ┌─────────┐            ┌────────────┐┌────────┐┌─────────────┐
q_0: ┤0        ├       q_0: ┤0           ├┤ RX(pi) ├┤0            ├
     │   ECR   │   =        │  RZX(pi/4) │└────────┘│  RZX(-pi/4) │
q_1: ┤1        ├       q_1: ┤1           ├──────────┤1            ├
     └─────────┘            └────────────┘          └─────────────┘

Matrix Representation:

ECR q0,q1=12(010i10−i00i01−i010)\begin{split}ECR\ q_0, q_1 = \frac{1}{\sqrt{2}} \begin{pmatrix} 0 & 1 & 0 & i \\ 1 & 0 & -i & 0 \\ 0 & i & 0 & 1 \\ -i & 0 & 1 & 0 \end{pmatrix}\end{split}
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 the X⊗ZX \otimes Z tensor order. Instead, if we apply it on (q_1, q_0), the matrix will be Z⊗XZ \otimes X:

     ┌─────────┐
q_0: ┤1        ├
     │   ECR   │
q_1: ┤0        ├
     └─────────┘
ECR q0,q1=12(001i00i11−i00−i100)\begin{split}ECR\ q_0, q_1 = \frac{1}{\sqrt{2}} \begin{pmatrix} 0 & 0 & 1 & i \\ 0 & 0 & i & 1 \\ 1 & -i & 0 & 0 \\ -i & 1 & 0 & 0 \end{pmatrix}\end{split}

Create new ECR gate.

Attributes

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

name

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 ECR gate (itself).

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