Quantum Information and Quantum Computing

There is a worldwide research effort exploring the consequences of quantum mechanics for information and computation. The field began with Feynman's 1981 proposal to build a computer that takes advantage of quantum mechanics and has grown enormously since Peter Shor's 1994 quantum factoring algorithm. Leaving aside the extensive experimental efforts to build a quantum computer, theory research in QI/QC (quantum information and quantum computing) investigates several themes:

  • Quantum algorithms and complexity. If a perfectly functioning quantum computer were built, which problems could it solve faster than conventional computers, and which problems do not admit any speedup?
  • Quantum information theory. How can we communicate and compute using quantum information in the presence of noise? What are the properties of entanglement?
  • Measurement and control. How can quantum information be useful in applications apart from computers and communication devices, such as clocks and precision measurements?
  • Applications and connections. How can ideas from QI/QC contribute to areas as diverse as convex optimization, black holes and condensed-matter physics?

QI/QC theory research at MIT spans all of these areas. The CTP faculty involved are Eddie Farhi, Jeffrey Goldstone (emeritus) and Aram Harrow, and the larger QI/QC group at MIT includes Isaac Chuang (EECS/physics), Seth Lloyd (Mech. Eng.), Jeff Shapiro (EECS), and Peter Shor (Math). Together this forms a large and vibrant group working in all areas of QI/QC.

Some of the notable contributions involving the CTP include the quantum adiabatic algorithm and quantum walk algorithms (Farhi, Goldstone), the first example of a problem for which quantum computers exhibit no speedup (Farhi, Goldstone), proposals for unforgeable quantum money (Aaronson, Farhi, Shor), a quantum algorithm for linear systems of equations (Harrow, Lloyd), efficient protocols for simulating quantum channels (Harrow, Shor) and both algorithms and hardness results for testing entanglement (Harrow). Ongoing research at MIT in QI/QC includes work on new quantum algorithms, efficient simulations of quantum systems, connections to convex optimization, understanding the role of decoherence in excitonic transport (e.g. in photosynthesis) and many other topics.

The larger QI/QC group at MIT shares a seminar series, a weekly group meeting, regular events for grad students.

Interdepartmental course offerings include an introductory and an advanced class in core QI/QC, a graduate class in quantum complexity theory and a special-topics class. Quantum information has also recently entered the undergraduate physics curriculum with a junior lab experiment on NMR quantum computing and some lectures in the 8.04/8.05/8.06 sequence on quantum computing.

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