2023 James Clerk Maxwell Medal and Prize

The proof by Dr Nikolas Breuckmann (together with Anurag Anshu and Chinmay Nirkhe) in June 2022 of the no low-energy trivial state (NLTS) conjecture, was described as “one of the biggest developments in theoretical computer science this year” by Quanta Magazine and has been accepted as a plenary talk at the prestigious Quantum Information Processing conference 2023.

The NLTS conjecture posits that there exist families of Hamiltonians with all low-energy states of non-trivial complexity. It was formulated in 2013 by Fields Medallist Michael Freedman and Matt Hastings at Microsoft Research. The conjecture was proven by Breuckmann and colleagues by showing that the recently discovered families of constant-rate and linear-distance low-density parity-check (LDPC) quantum codes correspond to NLTS local Hamiltonians. This result implies that quantum entanglement is not necessarily as sensitive to temperature as previously thought, and is a step towards proving the quantum PCP conjecture, considered the most important open problem in quantum information theory.

This result built upon Breuckmann’s pioneering work on quantum error correction, including the introduction (with Jens Eberhardt) of balanced product quantum codes in December 2020. All currently known constructions of constant-rate and linear-distance quantum LDPC codes are based on the balanced product construction. For this work, he gave a plenary talk at the 2022 Quantum Information Processing conference and a presentation at the Simons Institute for the Theory of Computing’s ‘Quantum Wave in Computing Reunion’ in July 2021, and was quoted by Quanta Magazine on related breakthroughs in January 2022.

Appointed Lecturer in Quantum Computing Theory at the University of Bristol in November 2022, Breuckmann has worked on quantum information theory, which lies at the intersection of mathematics, physics and computer science. He and his PhD supervisor, Professor Barbara Terhal, developed the space-time circuit-to-Hamiltonian construction that maps any quantum computation onto a model where each qubit has its own time, which was included in the IOP Journal of Physics A: Highlights of 2014 Selection. In his PhD, he showed how hyperbolic geometry can be used to reduce the overhead cost for making quantum computers fault-tolerant.

In 2017, he was awarded a University College London Quantum Science & Technology Institute  Postdoctoral Fellowship in Quantum Technologies, which he deferred for a year to work for PsiQuantum, a prominent Silicon Valley-based quantum computing startup. During his time at University College London, he filed with his PhD student Oscar Higgott a US patent titled ‘Subsystem codes with high thresholds by gauge fixing and reduced qubit overhead’.