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)

Building Grover's search algorithm

Let's take our first bite into Grover's search algorithm, one of the more straightforward quantum algorithms for solving an actual problem using quantum computing, namely finding information in an indexed but unsorted database. As we discussed in A quick interlude on classical search, Grover is expected to be quadratically faster than its classical counterpart.

In Qiskit Terra, we can create an implementation of Grover that uses a phase-kickback oracle combined with another neat trick: phase amplification. Phase amplification increases the amplitude of the correct phase-shifted answer and thereby increases the probability of that outcome when you measure your circuit.

First, we create a so-called oracle function, which is designed to take as input a set of qubits in initial superposition and switch the phase of the correct answer by , while leaving the phase of the incorrect answers alone. The oracle circuit is what is called...