Benjamin Schumacher

Feynman diagrams are a powerful tool for analyzing events in the quantum world. Some diagrams show particles moving forward and backward in time, while other particles appear from nowhere and disappear again. All are possible quantum scenarios, which you learn how to plot.

Twelve billion miles from Earth, the Voyager spacecraft is sending back data with just a 20-watt transmitter. Make sense of this amazing feat by delving into the details of the Nyquist-Shannon sampling theorem, signal-to-noise ratio, and bandwidth-concepts that apply to many types of communication.

The uncopyability of quantum information raises the possibility of quantum cryptography - an absolutely secure method for transmitting a coded message. This lecture tells how to do it, noting that a handful of banks and government agencies already use quantum cryptography to ensure the security of their most secret data.

You explore quantum information and quantum computing - Dr. Schumacher's specialty, for which he pioneered the concept "qubit," the unit of quantum information. You learn that unlike classical information, such as a book or musical recording, quantum information can't be perfectly copied.

How is information measured and how is it encoded most efficiently? Get acquainted with a subtle but powerful quantity that is vital to the science of information: entropy. Measuring information in terms of entropy sheds light on everything from password security to efficient binary codes to how to design a good guessing game.

DNA, RNA, and the protein molecules they assemble are so interdependent that it's hard to picture how life got started in the first place. Survey a selection of intriguing theories, including the view that genetic information in living cells results from eons of natural computation.

The interferometer from the previous lecture serves as a test case for introducing the formal math of quantum theory. By learning a few symbols and rules, you can describe the states of quantum particles, show how these states change over time, and predict the results of measurements.

Return to the concept of entropy, tracing its origin to thermodynamics, the branch of science dealing with heat. Discover that here the laws of nature and information meet. Understand the influential second law of thermodynamics, and conduct a famous thought experiment called Maxwell's demon.

Accompany the young Claude Shannon to the Massachusetts Institute of Technology, where in 1937 he submitted a master's thesis proving that Boolean algebra could be used to simplify the unwieldy analog computing devices of the day. Drawing on Shannon's ideas, learn how to design a simple electronic circuit that performs basic mathematical calculations.

You explore the intriguing capabilities of quantum computers, which don't yet exist but are theoretically possible. Using the laws of quantum mechanics, such devices could factor huge numbers, allowing them to easily decipher unbreakable conventional codes.