Friday, December 21, 2007

Qubits: What I've learned so far today

Quantum computation relies on the ability to coherently manipulate the quantum state of qubits. However, unavoidable coupling to the environment gives the qubit a finite lifetime. It has been proposed that the use of a geometric phase (or Berry's phase, a topological phase that accumulates as an object traverses a path) should be more robust to the effects of decoherence. Leek et al. (p. 1889, published online 22 November) describe the observation of this geometric phase in a superconducting qubit, which they claim might bring fault-tolerant quantum computation a step closer. [from Science CiteTrack: This Week In Science e-mail newsletter]

Wikipedia tells me that a qubit is a unit of quantum information. Okay. In addition, "Benjamin Schumacher discovered a way of interpreting quantum states as information. He came up with a way of compressing the information in a state, and storing the information on a smaller number of states. This is now known as Schumacher compression. In the acknowledgments of his paper (Phys. Rev. A 51, 2738), Schumacher states that the term qubit was invented in jest, during his conversations with Bill Wootters.

In other news, unrelated, the purported "Word of the Year"" is "woot"!


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