User:Qubissential/sandbox

Toby Cubitt is a British physicist and reader at University College London. His research investigates a variety of problems in quantum information and many-body quantum physics. In 2019 he was awarded the Whitehead Prize by the London Mathematical Society for fruitfully combining quantum information and complexity theory techniques with many-body quantum physics. He is best known for proving that the spectral gap problem is undecidable.  He is a founder of the quantum technologies startup Phasecraft.

Education
Cubitt was educated in Luxembourg. Following this, he undertook a BA and MSci in Natural Sciences at Churchill College, Cambridge University specialising in physics. He then undertook a PhD at the Max Planck Institute under supervisor Ignacio Cirac specialising in quantum information theory.

Research and career
As of 2019, Cubitt is a reader in quantum information in the computer science group at University College London, focusing primarily on applying techniques from quantum information theory to physics. Previously he has done postdoctoral research at Bristol University and Complutense University of Madrid. Notable research includes showing that the problem of deciding whether the spectral gap of a Hamiltonian is gapped or gapless in the thermodynamic limit is undecidable.

Research
Cubitt's research has covered quantum information theory, quantum computing, and condensed matter physics. In particular, his work has been fruitful in combining these fields.

Undecidability of the Spectral Gap
With collaborators Michael Wolf and David Perez-Garcia, Cubitt showed that the general problem of finding whether the spectral gap of a Hamiltonian specified on a lattice is zero or greater than some constant is undecidable. The result is significant in that the spectral gap determines the fundamental behaviour of quantum systems. Furthermore, it leaves open the possibility that the Yang-Mills mass gap conjecture is undecidable. This result led to Cubitt and collaborators to be included in a feature article in Scientific America.

Awards
Cubitt has received the Whitehead prize in recognition of his contributions to mathematical physics, in particular his work combining computability and computational complexity theory with many-body quantum physics.