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 more than 2 qubits

In addition to the single-qubit and two-qubit gates, Qiskit® also supports 3- and more qubit gates. We will use one of them, the Toffoli gate when we build the 3-qubit Grover search algorithm circuit in Chapter 9, Grover's Search Algorithm. We are including the Fredkin gate for completeness and will not be using it in any other examples; feel free to try it out.

The multi-qubit gates in this recipe use 2, more, and 1 controlling qubit respectively:

  • Toffoli: Controlled-controlled NOT (CCX), which takes 2 qubits as input and flips the third if both controlling qubits are set.
  • MCX: Multi-controlled NOT takes a number of qubits (controlling) as input and flips the controlled qubit if all are set.

    There is (in principle) no limit to the number of controlling qubits that you can use with your gates. In the 4- and more qubit Grover search algorithm circuit in Chapter 9, Grover's Search Algorithm, we build a 4-qubit CCCX controlled...