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Two bits on qubits

MAR 01, 2008

DOI: 10.1063/1.4796801

David Mermin

Mermin replies: The enticing arguments that Dave Bacon tries so well to refute were not in my Reference Frame columns, which I’m delighted he enjoyed. The point is put best in my new book, 1 where I also note that q-bit would indeed be better than Qbit, were it not that common expressions such as 2-Qbit gate fail to work when written in the form 2-q-bit gate. To solve the problem, I drop Dirac’s hyphen but put Q in uppercase (which the qbit Bacon wrongly attributes to me does not) to emphasize that it functions as the name of a letter and not as part of another grotesquely spelled word.

Qbit for the quantum object parallels the equally important Cbit for the classical object (clbit would be ridiculous). The capitalization convention gives rise to the useful term Bit, which refers collectively to both kinds of physical objects, as opposed to bit, which refers only to a number that can be 0 or 1.

I agree with Bacon that qubit has achieved its current status because of its spurious resemblance to cubit, 2 but I do not agree that the foot deserves to die. It should be redefined 5 millimeters downward to a light nanosecond 3 a couple of years after our backward nation finally goes metric, which I confidently expect to happen in a century or two.

Setting aside the fact that transliterations of foreign proper nouns notoriously violate all kinds of rules, I note that Qumran is pronounced k’mran. This class of examples would require qubit to be pronounced k’bit.

It may be quixotic (but certainly not Qxotic) to try to correct the spelling of an entire community, but I owe it my best shot. What else is retirement good for?

References

  1. 1. N. D. Mermin, Quantum Computer Science: An Introduction, Cambridge U. Press, New York (2007), p. 3.

  2. 2. Ref. 1, p. 4.

  3. 3. N. D. Mermin, It’s About Time: Understanding Einstein’s Relativity, Princeton U. Press, Princeton, NJ (2005), p. 22.

More about the Authors

David Mermin. Ithaca, New York, US .

This Content Appeared In
pt-cover_2008_03.jpeg

Volume 61, Number 3

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