### Area I Applied Physics and Devices: Physics of Information

“Information” is an abstract concept, a measure of “surprise,” which governs computation and communication, while “Physics” describes the natural world, with laws governing the behavior of atoms, electrons, and other concrete objects. Research in the topic of *Physics of Information* in Area IV links these two fields, and seeks to discover and understand how new kinds of information processing and communication are enabled by different laws of physics. Two examples illustrate our efforts in the Physics of Information:

Beyond Silicon—the most successful platform for modern information processing is the silicon chip, but at present rates of advancement, individual logic gates will soon reach size scales at which bits of information will need to be encoded in individual molecules or atoms, or in single electrons and photons; and time scales will soon reach beyond nanoseconds, to the need for control at the picosecond and femtosecond regime. Significant research thus focuses on alternative devices and system models for computation. This includes the development of all-optical logic gates, realized with a microfabricated integrated waveguide Mach-Zehnder interferometer, using the nonlinearity of an embedded semiconductor material to allow photons to interact with each other. Nonlinear optics also provides, in the ultrafast regime, femtosecond optical frequency combs, which allow absolute measurement to one part in 10^{15}, useful for realizing high speed, ultra-low noise analog-to-digital converters. And at sub-nanometer length scales, carbon nanotubes allow capture and control of single molecules for novel post-silicon electronic devices.

Quantum Information—ultimately, size and time scales are reached at which the physical laws switch from the classical behavior of Newton and Maxwell to the quantum behavior governed by Schrödinger and von Neumann. Surprisingly, quantum systems can solve certain mathematical and computational problems exponentially faster than is known possible with just classical systems, as has been demonstrated in experiments at MIT. Research here in Area IV spans a broad range of physical systems, using microfabricated chips to trap and control single atoms, and microscopic superconducting Josephson junctions to realize quantum bits. These devices have coherence times up to one second, and build on results by Area IV faculty demonstrating simple quantum algorithms such as quantum factoring, with nuclear spins in molecules. Research in Area IV also shows how measurement with quantum states can improve imaging resolution beyond the diffraction limit, and how quantum states can allow communication at rates exceeding the Shannon limit.

Physics of Information in Area IV also plays a strong role in a major program at MIT known as interdisciplinary Quantum Information Science and Engineering (iQuISE), an NSF-funded Integrative Graduate Education, Research, and Training (IGERT) program supporting graduate students, and the development of a comprehensive curriculum in quantum information science and engineering at MIT.

Check MIT’s Open Course Ware (OCW) or the MIT Catalogue to see more information regarding a number of undergraduate and graduate subjects that address *Physics of Information* including:

Undergraduate Subjects: |
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6.050J | Spring | Information, Entropy and Computation |

First Year and Introductory Graduate Subjects: |
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6.443J | Spring | Quantum Information Science (meets with 8.371) |

6.453 | Fall | Quantum Optical Communication |

6.728 | Fall | Applied Quantum and Statistical Physics |

8.422 | Spring | Atomic and Optical Physics II |

2.111J | Fall | Quantum Computation |

22.51 | Fall | Quantum Theory of Radiation Interactions |

More Advanced Graduate Subjects: |
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6.291 | Fall, Spring | Seminar in Systems, Communications, and Control Research |

6.763 | Fall | Applied Superconductivity |

6.781 | Spring | Submicrometer and Nanometer Technology |

6.896 | Fall | Quantum Complexity Theory (offered Fall 2008 by Prof. Aaronson) |

The following seminars cover material relevant the *Physics of Information* in Area IV Engineering Physics:

Optics and Quantum Electronic Seminar

Wednesdays, 11 am, room 36-428, Haus Room

Quantum Information Science at MIT

Center for Ultracold Atoms Seminar

Center for Integrated Photonic Systems (CIPS) Brown Bag Seminar Series

NanoStructures Lab (NSL) Group Meeting, Fridays, 3pm, room 36-428

The following research programs also contribute to the *Physics of Information*:

Center for Extreme Quantum Information Theory

Quantum Information Science at MIT

iQuISE: Interdisciplinary Quantum Information Science and Engineering