Book Image

Quantum Computing in Practice with Qiskit® and IBM Quantum Experience®

By : Hassi Norlen
5 (1)
Book Image

Quantum Computing in Practice with Qiskit® and IBM Quantum Experience®

5 (1)
By: Hassi Norlen

Overview of this book

IBM Quantum Experience® is a leading platform for programming quantum computers and implementing quantum solutions directly on the cloud. This book will help you get up to speed with programming quantum computers and provide solutions to the most common problems and challenges. You’ll start with a high-level overview of IBM Quantum Experience® and Qiskit®, where you will perform the installation while writing some basic quantum programs. This introduction puts less emphasis on the theoretical framework and more emphasis on recent developments such as Shor’s algorithm and Grover’s algorithm. Next, you’ll delve into Qiskit®, a quantum information science toolkit, and its constituent packages such as Terra, Aer, Ignis, and Aqua. You’ll cover these packages in detail, exploring their benefits and use cases. Later, you’ll discover various quantum gates that Qiskit® offers and even deconstruct a quantum program with their help, before going on to compare Noisy Intermediate-Scale Quantum (NISQ) and Universal Fault-Tolerant quantum computing using simulators and actual hardware. Finally, you’ll explore quantum algorithms and understand how they differ from classical algorithms, along with learning how to use pre-packaged algorithms in Qiskit® Aqua. By the end of this quantum computing book, you’ll be able to build and execute your own quantum programs using IBM Quantum Experience® and Qiskit® with Python.
Table of Contents (12 chapters)

Using gates on 2 qubits

Two-qubit gates such as controlled gates are slightly different from ordinary 1-qubit gates; they let you create interaction between your qubits. In general, this translates into using 1 qubit as the control qubit, and the other as the acted-on qubit. Mathematically, this is not super complex, but intuitively you might have to think once or twice about what is going on.

Getting ready

The first 2-qubit gate that we'll touch on is the Controlled-NOT gate that we saw in Chapter 4, Starting at the Ground Level with Terra. The CX gate is generally used to create entanglement between qubits if the control qubit is in a superposition.

A CX gate where the controlling qubit is the second qubit and the controlled qubit the first can be expressed as the following matrix:

This corresponds to the following circuit:

Figure 6.15 – CX gate from q_1 to q_0

The way you interpret this is to run the first...