# What if Archimedes Had A Quantum Computer To Estimate Pi?

An algorithm to calculate Pi on IBM’s quantum computers honors Pi Day—and helps us understand how a quantum computer works.

Ever since Archimedes hit upon a value for Pi in the third century B.C., mathematicians have used a variety of methods and instruments to puzzle over it.

And no wonder. Pi is a fascinating fact of nature: the universal ratio of a circle’s circumference to its diameter, expressed by a never-ending string of numbers.

Most of us learned Pi in middle school: 3.1415… stretching seemingly to infinity. The number is why every March 14 (3/14) is celebrated as Pi Day.

Experts have had access to increasingly powerful computing tools to work with Pi, allowing them to spin out ever-longer versions of the number, which surpassed 31 trillion decimal places last year.

Some IBM researchers are also exploring Pi, not to find the next trillion digits, but to instead educate people about a new approach to computing—quantum computing.

## A Quantum Tutorial

Quantum computers process information by harnessing the laws of quantum mechanics. So, unlike their classical cousins’ on-off-only, binary-powered processing of 1s and 0s, their quantum bits (or qubits) exist in multiple states between 1 and 0. Picture a spinning coin that is both heads and tails as it spins.

What this means, briefly put, is that quantum computers work the way nature does. And it’s why quantum computing could be better suited to helping us understand nature—like simulating chemical reactions to help develop more stable batteries or getting a clearer understanding of molecules to create therapeutic drugs.

In honor of Pi Day 2020, IBM—which makes a quantum computer available to anyone through the cloud—is releasing a new tutorial that explains how to estimate the value of Pi on a quantum computer.

The tutorial, part of an open-source online textbook on Qiskit software, takes you through the steps to apply a well-known quantum algorithm on different numbers of connected qubits. The goal is to improve the quantum computer’s ability to estimate Pi by adding more qubits—you may not get to Pi right away—and to inspire Pi enthusiasts everywhere to learn more about quantum computing and even give it a try.

Abe Asfaw, Global Lead of Quantum Education at IBM Quantum and Qiskit Developer Advocate, IBM Systems

“The thing we’re trying to do here is to stay away from computing a million digits of Pi and more to use the theme of Pi Day to educate people on what quantum algorithms look like,” explains Abraham “Abe” Asfaw, global lead of quantum education at IBM.

Try Abe’s Tutorial on Calculating Quantum Pi for yourself, here.

“IBM bringing online a quantum computer really democratizes access. It goes from being a very expensive, limited-access kind of thing to being something anyone can play with if they have ideas,” Asfaw says. “The goal of our education mission is to make sure that when people come to use our quantum computers, now that they have access, they have all the tools they need to learn and start using them.”

And so, Pi Day in the quantum era may become something different—no longer an exercise in using classical computers to chase the digits of Pi. Instead, Pi Day may come to represent our quest to better understand our universe through quantum computing.

Find out how our researchers apply math in their work on quantum computing, as well as other key areas including AI and healthcare:

## IBM Quantum

### Quantum starts here

Previous Post

Next Post

More Quantum Computing stories

### IBM Research at IEEE World Congress on Services 2019

IBM Research is proud to have participated in the 2019 IEEE World Congress on Services and played a key sponsorship role.