Scott Aaronson in Big Questions Online:
Picture, if you can, the following scene. It’s the year 2040. You wake up in the morning, and walk across your bedroom to your computer to check your email and some news websites. Your computer, your mail reader, and your web browser have some new bells and whistles, but all of them would be recognizable to a visitor from 2014: on casual inspection, not that much has changed. But one thing has changed: if, while browsing the web, you suddenly feel the urge to calculate the ground state energy of a complicated biomolecule, or to know the prime factors of a 5000-digit positive integer—and who among us don’t feel those urges, from time to time?—there are now online services that, for a fee, will use a quantum computer to give you the answer much faster than you could’ve obtained it classically. Scientists, you’re vaguely aware, are using the new quantum simulation capability to help them design drugs and high-efficiency solar cells, and to explore the properties of high-temperature superconductors. Does any of this affect your life? Sure, maybe it does—and if not, it might affect your children’s lives, or your grandchildren’s. At any rate, it’s certainly cool to know about.
Privacy and security are different as well in this brave new world. When you connect to a secure website—let’s say, to upload sensitive financial data—there’s still a padlock icon in your web browser; indeed, the user experience is pretty much the same as it was in 2014. But, you’ve heard, the previous mechanism that encrypted your data was broken by quantum computers, with their ability to factor large numbers.