What is a quantum computer? As Google's Matt Braithwaite puts it, "Quantum computers are a fundamentally different sort of computer that take advantage of aspects of quantum physics to solve certain sorts of problems dramatically faster than conventional computers can." They are able to complete much more complex tasks with far greater efficiency than today's consumer grade computers. Right now, quantum computers only exist in the form of small experimental machines, but companies such as Google, IBM, and Microsoft are working on larger and more powerful versions.
While quantum computers can, in theory, solve a range of different problems, one possible application for them is to break complex security encryption. And even though we don't have the technology today to accomplish this, Google is looking to take measures to safeguard against this possibility in the future by developing encryption for Google Chrome that will stand up to quantum computers. Google states that they "do not wish to make our selected post-quantum algorithm a de-facto standard", but rather aim to explore the topic of post-quantum cryptography to build experience and knowledge. They plan to work on this for a period of fewer than two years. Google credits Erdem Alkim, Léo Ducas, Thomas Pöppelmann and Peter Schwabe for creating the "New Hope" algorithm, which is the basis for their experiments. The algorithm was created on the idea of building post-quantum security for TLS (Transport Layer Security), which is currently used to provide cryptographic security over a network.
Google is currently testing this in the Canary version of Chrome, so if you'd like to give it a try you'll have to download it from Google's website. To verify that this experiment is being used, you can open the security panel of Chrome, which can be done by clicking the icon in the search bar to the left of the URL. Next, click details. From this page, look for "CECPQ1". It may not be available on all Google domains; because it is still experimental, not many Google servers will be using it yet. Also, be aware that the Canary version of Chrome includes experimental features that have not been fully tested, and may have some issues, so install it at your own risk.