My grandfather liked to write letters to the editor. I think I inherited this disease from him. Here are the contents of a recent letter I wrote to the editor of Physics Today which I hope some of you may find amusing.
I greatly enjoyed reading N. David Mermin’s last two Reference Frame columns on factoring and quantum computing (“What has quantum mechanics to do with factoring?”, Physics Today, April 2007, page 8 and “Some curious facts about quantum factoring”, Physics Today, October 2007, page 10.) However as the proud one-time owner of the California license plate “QUBIT” (which I had occasion to park beside a “QUARK” New Mexico license plate), I feel it is my duty to cheerfully disagree with Mermin’s choice to denote quantum bits as “qbits.” His slander of the traditional shortened spelling of quantum bit as “the vulgar spelling qubit” is nothing less than laying down the gauntlet to the proud worldwide community of heterographic homophone lovers, many of whom I call my friends.
Mermin’s arguments are deceptively enticing : that “Qubit” violates the English rule that “qu” should be followed by a vowel, that no one would ever call the ear appliance a “Qutip,” and finally that Dirac with good reason called them “q-numbers” not “qunumbers.” (One reason might have been enough, but cube it, and certainly no one will argue back at you.)
Let us rebut these arguments one by one. First of all, if Mermin is serious about his respelling of the shortened form of quantum bits, then most certainly he should choose “q-bit” instead of “qbit,” as the only word with a consonant following a “q” in the oxford English dictionary is the crippling child of circumstance “qwerty” to describe a keyboard. And, having settled on “q-bit” one is faced with quite a dilemma. Writing down “q-bit” immediately reminds one of “Q-tip” and, worse for those of us from the video game age, of “Q-Bert” (or “Q*Bert”), the name of an addictive video game featuring an eponymous alien who hopped on a tricolored pyramidal staircase. Now while Mermin may find no discomfort in hearing echoes of “Q-tip” in writing down “Q-bit,” I would think that the majority of physicists (not to mention computer scientists) would prefer not to be reminded of ear infections or even of hopping aliens when they transcribe their serious scientific work. Finally, I note that both “q-number” and “Q-tip” arose at the same time (“Q-tips” originally being called “Baby Gays,” were renamed to “Q-tips” in 1926: the “q” stood for “quality”) With no disrespect to Dirac (who seemed to have a thing for full letter initials), history, as measured by the success of “q-number” in today’s scientific nomenclature versus the ubiquity “Q-tip” to describe cotton swaps, has clearly decided that the “q-” prefix works better for brand names than for scientific terms. In short: let us keep the corporate branding of science off our beloved quantum bits.
Lastly, and most importantly for the progress of science, the fact that “qubit” is an intentional homophone of “cubit” is not vulgar but rather a blessing in disguise. “Cubit” is an English unit of length, roughly equal to the length of a forearm. And it is this “roughly” which should offend the heart of any physicist. Like the “foot” the “cubit” is an imprecise unit whose lack of precision makes me think it deserves to die (can you use “cubit” on your physics tests? no!), and I can think of no better death than its replacement by “qubit,” a precise unit of quantum information.
(As an addendum to the beautify of this homophone, one should not overlook the fact that “cubit” is most often associated with lengths in biblical texts, and, despite Mermin’s claim to the contrary, there are English words with “qu” followed by a vowel, albeit proper nouns, notably “Qumran” which is the settlement nearest where the dead sea scrolls were discovered.)
Long live “qubits.” And may “qbits” or their dirty cousins “Q-bits” only rear their head in a future quantum computing company or in a medical journal describing bits of cotton swap lodged in the ear.
 “From Cbits to Qbits: Teaching computer scientists quantum mechanics,” American Journal of Physics — January 2003 — Volume 71, Issue 1, p. 23.