Creating Quantum Circuits with Matrices and Qiskit provides gate

This guide covers advanced techniques for creating quantum circuits in QIRT, including method chaining and adding custom unitary operators.

Method Chaining

QIRT's QuantumCircuit class supports method chaining, which allows you to build circuits more concisely. Here's how you can create a Bell state circuit using method chaining:

from QIRT import QuantumCircuit

# Create a two-qubit quantum circuit and add gates using method chaining
circuit = QuantumCircuit(2).h(0).cx(0, 1)

# Visualize the circuit
circuit.draw()

>> Output:

Method chaining can make your code cleaner and more readable, especially for constructing more complex circuits.

Adding Custom Unitary Operators

QIRT allows you to add custom unitary operators to your quantum circuits using the unitary method. This is particularly useful when you want to apply a specific unitary transformation that isn't available as a built-in gate.

Example: Adding a CNOT Gate

Let's add a CNOT gate to a quantum circuit using the unitary method:

from QIRT import QuantumCircuit

# Create a quantum circuit
circ = QuantumCircuit(2)

# Unitary matrix for a CNOT gate
cnot_matrix = [ 
                [1, 0, 0, 0],
                [0, 1, 0, 0],
                [0, 0, 0, 1],
                [0, 0, 1, 0]
              ]

# Add a CNOT gate to the circuit using a unitary matrix
circ.unitary(matrix=cnot_matrix, qubits=[0,1], label='CNOT')

# Visualize the circuit
circ.draw()

>> Output:

This adds a CNOT gate to the circuit using a unitary matrix.

The unitary method allows you to apply any custom unitary matrix to specified qubits. The matrix parameter takes the unitary matrix, qubits specifies which qubits to apply the gate to, and label allows you to give a name to your custom gate.

Finding More Quantum Gates

QIRT is built on top of Qiskit, which is a comprehensive and widely-used framework for quantum computing. As such, QIRT provides support for many different quantum gates. To explore all available gates and their usage, you can refer to the Qiskit Circuit Library.