Your Majesties, your Royal Highnesses, Dear Friends and Colleagues, Ladies and Gentlemen,

Let me, at the close of this wonderful banquet, evoke the memory of Erwin Schrödinger. His work has had an impact on all the fields of science and culture celebrated tonight. He received the Nobel Prize in Physics in 1933 for finding the equation which explains the behavior of matter at the quantum level. Schrödinger’s equation also accounts, at least in principle, for the structure of all the molecules studied in chemistry and  biology. It has also a strong influence on the world economy. Most of the devices which have changed our lives are based on quantum physics, from the laser to the transistor, from the GPS to the cell phone, from the magnetic resonance imaging to the global communication network. Schrödinger’s equation is essential to explain the workings of these technological marvels, whose sales reach billions of dollars.

What about Schrödinger’s merits in literature? He may not have written any novel, but he invented a character about which a lot has been written in many books, a character which has even featured in movies, generating endless metaphysical discussions. I am of course referring to the legendary Schrödinger’s cat, suspended between life and death by the laws of quantum physics and its superposition principle. In his famous thought experiment, Schrödinger could have chosen an inanimate object or a less lovable living being, a cockroach for instance. Just think about it. What about Schrödinger’s cockroach? The story would have been as demonstrative to explain the strange logic of the quantum world, but much less impressive. By the stroke of genius of choosing the right animal in the right dramatic situation, and by having fathered an immortal character as famous as the Cheshire cat of Alice in Wonderland, Schrödinger has made an impact on the world culture.

My fondness for this quantum feline is of course biased. David Wineland and I have been awarded the Nobel Prize for creating miniature versions of this famous cat, made of a few atoms or photons. We have both been accompanied in our long research adventure by wonderful colleagues, without whom we would never have succeeded. We are very glad that many of them are here this evening. Other groups in the world are also working in this field, raising various ersatz of laboratory cats and trying to preserve as long as possible their quantumness. What is the future of these cats? One easy – may be too easy – answer, is that they will turn into a quantum computer. I don’t know. I rather guess that they will lead to some unforeseen application, even more astonishing than this mythical machine. When the minister Gladstone asked Faraday what his research on electricity could be good for, the nineteen century physicist replied “One day, sir, you may tax it”. We are tempted to give our politicians the same answer: “One day, you may tax Schrödinger’s cat“.

I must add though that, if someone was dubious about the taxability of his cat, it was Schrödinger. Not believing that it would one day be possible to really perform such experiments, he once wrote: “We never experiment with just one electron, or atom or small molecule. In thought experiments, we assume that we do; this invariably entails ridiculous consequences”. In spite of the admiration we have for Schrödinger, my friend David Wineland and I must on this point disagree with him: for us, the consequences, culminating in this magnificent evening, have been far from ridiculous!