# Toby 'qubit' Cubitt

## Who am I?

I'm a nationality-confused European, born and raised in Luxembourg but technically British.

I went to the European school in Luxembourg, graduating with the European Baccalaureate in 1998. From there, I hopped across the Channel to Churchill College, Cambridge, studying physics under the Natural Sciences Tripos at the University of Cambridge.

After graduating in 2002, I decided to see what the other end of Europe was like, and moved to the Max Planck Institute for Quantum Optics just outside Munich, Germany to do a PhD in quantum information theory under the wonderful Ignacio Cirac.

After finishing my PhD in 2006, I hopped *back* across the
Channel, defecting from physics to maths *en route* (or maybe I'm
just masquerading as a mathematician...), to
the mathematics section of the
quantum information theory
group at the University of
Bristol. I stayed there as a postdoc for four years, the latter two
as a Leverhulme Early Career Fellow.

In 2010, my Leverhulme fellowship over, it was clearly time to live in
a new country! So, still masquerading as a mathematician (or maybe I've
really been converted now...), I moved to Spain with a Juan de la Cierva
fellowship, joining
the Mathematics and
Quantum Information Theory group of old MPQ friend David
Pérez-García, in
the Departamento de
Análisis (wow! just like a *real* mathematician!)
within the Facultad de Ciencias
Matemáticas at the Universidad
Complutense de Madrid.

After two-and-a-bit fantastic years in Madrid, I was awarded a Royal Society University Research Fellowship. So, time to move back to the UK again, this time back to my alma mater, the University of Cambridge, where I was in the quantum information theory group based in the Department of Applied Maths and Theoretical Physics (thereby neatly sidestepping the need to resolve the physicist/mathematician ambiguity...).

Another two-and-a-bit years later, having worked in physics, applied maths and even pure maths departments, I felt the urge to complete the full set. So I moved my Royal Society fellowship to the Department of Computer Science at University College London.

## Why *'qubit'* ?!

If you're accessing this site without a computer, I'd be very interested to hear how you managed it...

In classical information theory, which is rooted in classical physics,
the fundamental unit of information is the
**bit** (which should be very familiar to anyone accessing
this site with a computer).

However, the real world is quantum mechanical. (You didn't know? then I recommend reading "In Search of Schrödinger's Cat" by John Gribbin). Quantum information theory is the study of information in our quantum mechanical universe. You may have heard of quantum computing, or quantum teleportation, which the popular press find sexy. Quantum information theory includes these, and many weirder things besides (such as entanglement - the subject of my PhD thesis, quite a few years ago now).

The term **qubit** was coined for the fundamental unit
of quantum information, analagous to the **bit** in
classical information theory. 'Qubit' is pronounced *kew-bit*.
'Cubitt' (my surname) is pronounced *kew-bit*.

People in the quantum information community respond to this curious
coincidence in one of three ways: a) they find it funny, b) they accuse
me of changing my name to fit my field of research, or c) they accuse me
of choosing my field of research to fit my name. Strangely, no one has
yet suggested that the term **qubit** was chosen in my
honour...

a) is fine by me, b) is provably untrue: my birth certificate predates the coining of the term by 13 years, and c) well... who knows how strong an effect nominative determinism really is?