Another Office Move

A year and a bit ago I had to move office at the University, after about 20 years in my previous office.   I moved from 12BB03 to 02AA04 – so up a level to the 4th floor, and across buildings from BB to AA.  My new office was pretty hard to work in with a constant drone coming from the plant room of Senate House outside it.  I am unable to filter out such noises and so I spent a year finding it pretty hard to function at work.  Now, though, I have moved offices again, to 28BC04, which is back to the floor (BC04) that I first had an office in when I arrived here in 2000.  I am not, alas, on the side of BC04 where I can see any plant life from my window, but otherwise the environent in this office is much bettern than the AA04 office.  

I await bookshelves so at the moment my office looks like this:

but hopefully it will be a bit more habitable soon. 
 

Unitary as a noun

Since working in the field of quantum computing, I've had to get used to seeing the word unitary used as a noun to mean a unitary object such as an operator or matrix.   

 Such a usage has yet to make it into any English dictionary that I've checked - not OED, Chambers, Cambridge, Merriam-Webster.  Of those, only OED do list one kind of nounal usage, with the definite article, meaning "that which is unitary" with a first example quotation give as:

Man loves the Universal, the Unchangeable, the Unitary - W. E. Channing, Perfect Life (1888)

(someone writing a thesis on quantum computing, please feel free to take that quote!)

 The bible of quantum computing, Nielsen and Chuang's textbook Quantum Computation and Quantum Information sticks to standard English usage, with unitary always an adjective, but there is at least one place where I could see an unwary reader thinking it was a noun.  On p71 (10th anniversary edition) they say

This result suggests the following elegant outer product representation of any unitary U.

Here, the symbol U is the noun and unitary is an adjective, and if they wanted a nounal usage of unitary I'm sure they'd've put a comma in there. 

To show an example of the contemporary nounal usage, I was going to pick the first paper in today's arXiv quant-ph section and show how it is done, but they very diligiently use unitary only as an adjective.  In fact, I had to scan through quite a few papers from today's quant-ph to find unitary as a noun, but here is an example (from arXiv:2507.07646):

Note that the state [...] is generated by a unitary acting on the initial state 

The latent lexicographer in me would be interested to know the first example of such a usage, but I fear it would be very hard to find.