David Deutsch

David Elieser Deutsch (/dɔɪtʃ/ DOYTCH; Hebrew: דוד דויטש; born 18 May 1953) is a British physicist at the University of Oxford who is often described as the "father of quantum computing". He is a visiting professor in the Department of Atomic and Laser Physics at the Centre for Quantum Computation (CQC) in the Clarendon Laboratory of the University of Oxford. He pioneered the field of quantum computation by formulating a description for a quantum Turing machine, as well as specifying an algorithm designed to run on a quantum computer. He is a proponent of the many-worlds interpretation of quantum mechanics.

Deutsch was born to a Jewish family in Haifa, Israel, on 18 May 1953, the son of Oskar and Tikva Deutsch. David attended Geneva House school in Cricklewood, London. His parents owned and ran the Alma restaurant on Cricklewood Broadway. He later attended William Ellis School in Highgate before reading Natural Sciences at Clare College, Cambridge, and taking Part III of the Mathematical Tripos. He went on to Wolfson College, Oxford for his doctorate in theoretical physics on quantum field theory in curved space-time, supervised by Dennis Sciama and Philip Candelas.

His work on quantum algorithms began with a 1985 paper, expanded with Richard Jozsa in 1992, to produce the Deutsch–Jozsa algorithm, one of the first examples of a quantum algorithm that is exponentially faster than any possible deterministic classical algorithm. In his nomination for election as a Fellow of the Royal Society (FRS) in 2008, his contributions were described as:

[having] laid the foundations of the quantum theory of computation, and has subsequently made or participated in many of the most important advances in the field, including the discovery of the first quantum algorithms, the theory of quantum logic gates and quantum computational networks, the first quantum error-correction scheme, and several fundamental quantum universality results. He has set the agenda for worldwide research efforts in this new, interdisciplinary field, made progress in understanding its philosophical implications (via a variant of the many-universes interpretation) and made it comprehensible to the general public, notably in his book The Fabric of Reality.

Since 2012, he has been working on constructor theory, a new approach to formulating fundamental physics in which laws are expressed not in terms of initial conditions and equations of motion, but in terms of which physical transformations are possible and which are impossible. Together with Chiara Marletto, he published a paper in December 2014 entitled "Constructor theory of information", which conjectures that information can be expressed solely in terms of which transformations of physical systems are possible and which are impossible.

In his 1997 book The Fabric of Reality Deutsch details his views on quantum mechanics and explains his "Theory of Everything". It aims not at the reduction of everything to particle physics, but rather mutual support among multiversal, computational, epistemological and evolutionary principles. His theory of everything is somewhat emergentist rather than reductive. There are four strands to his theory:

In a 2009 TED talk, Deutsch expounded a criterion for scientific explanation, which is to formulate invariants: "State an explanation publicly, so that it can be dated and verified by others later, that remains invariant [in the face of apparent change, new information, or unexpected conditions]".

Invariance as a fundamental aspect of a scientific account of reality has long been part of philosophy of science: for example, Friedel Weinert's book The Scientist as Philosopher (2004) noted the presence of the theme in many writings from around 1900 onward, such as works by Henri Poincaré (1902), Ernst Cassirer (1920), Max Born (1949 and 1953), Paul Dirac (1958), Olivier Costa de Beauregard (1966), Eugene Wigner (1967), Lawrence Sklar (1974), Michael Friedman (1983), John D. Norton (1992), Nicholas Maxwell (1993), Alan Cook (1994), Alistair Cameron Crombie (1994), Margaret Morrison (1995), Richard Feynman (1997), Robert Nozick (2001) and Tim Maudlin (2002).