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Question: How do I explain quantum computing?

Adam Lyon: I read a good analogy somewhere about how quantum computing relates to traditional (classical) computing. The difference between quantum computers and regular computers is like the difference between lasers and light bulbs. You wouldn't light up your dining room with lasers— if you want to see your food, you use light bulbs. Lasers and light bulbs serve different purposes even though they both involve light. Similarly, you're not going to balance your check book, surf the web or tweet your friends with a quantum computer. A quantum computer will solve a different set of problems.

Quantum computers may be good at solving problems that scale up too quickly for regular (or "classical") computers. For example, breaking cryptography involves factoring large numbers. The reason why things like RSA security work well is because it would take even the fastest supercomputer much longer than the age of the Universe to factor the numbers involved. Theoretically, a quantum computer could solve the problem in hours. Quantum computers may also be useful to simulate chemical compounds with large numbers of atoms or molecules. Current computers can only simulate a tiny number of atoms/molecules, and scaling up increases the computing time astronomically. We are now starting a program to determine how quantum computing may help with computational problems in High Energy Physics.

While quantum computers have been a theoretical idea for several decades, it's only recently that scientists have figured out how to build them. The past year has seen the technology for superconducting quantum computers really take off, and several companies such as Intel, Google, IBM, and Microsoft have quantum computers available for use. The quantum computers they have right now, however, aren't powerful enough to do anything super-useful, except to teach us more about quantum computing! But bigger computers that may be able to solve real-world problems are coming very soon, and many people are waiting impatiently to try them out.