Physics

Department staff

Dr John Samson

Photo of Dr John Samson

Senior Lecturer in Physics

1976-1979 Natural Sciences Tripos (Physics and Theoretical Physics), University of Cambridge, BA (first class honours)

1979-1982 PhD (Local Moments in Itinerant Electron Magnetism, supervisor V Heine), Cavendish Laboratory, University of Cambridge

1982-1984 Postdoctoral associate, Laboratory of Atomic and Solid State Physics, Cornell University

1984-1986 Postdoctoral associate, Max-Planck-Institut für Festkörperforschung, Stuttgart

1986- Department of Physics, Loughborough University

Member of the Quantum Systems Engineering Research Group

Phase space methods

Each formalism of quantum mechanics, although mathematically equivalent, brings unique insights and methods. The representation of quantum states as functions in phase space, originated by Wigner, allows easy visualisation of important features such as coherence.  Our new approach unifies the treatment of Wigner functions in both continuous systems and the discrete systems relevant to quantum information technologies. We are applying such techniques to a variety of areas, including entanglement verification, graph theory and quantum chemistry.

Quantum computing

Optimisation problems, such as finding the ground state of a spin glass, are in general NP hard, meaning that there is (almost certainly) no classical algorithm to find the optimum solution in polynomial time. Adiabatic quantum computing (or quantum annealing) provides a means to approximate the ground state, by smoothly adjusting the Hamiltonian of the system, in time that may be competitive with classical algorithms. We are investigating the features that distinguish "easy" and "hard" problems for this algorithm.

Other research interests

  • Quasiprobabilities, from Wigner functions to the Monte Carlo sign problem
  • Graph theory and quantum mechanics
  • Correlated electrons
  • Polarons and bipolarons
  • Superconductivity

Selected publications:

Rundle RP, Mills PW, Tilma T, Samson JH, Everitt MJ. Simple procedure for phase-space measurement and entanglement validation, Phys Rev A 96 022117 (2017)

Tilma T, Everitt MJ, Samson JH, Munro MJ, Nemoto K. Wigner Functions for Arbitrary Quantum Systems, Phys Rev Lett 117 180401 (2016)

Sowa AP, Everitt MJ, Samson JH, Savel’ev SE, Zagoskin AM, Heidel S, Zúñiga-Anaya JC. Recursive simulation of quantum annealing, J Phys A 48 415301 (2015)

Alexandrov AS, Samson JH, Sica G. Superlight small bipolarons from realistic long-range Coulomb and Fröhlich interactions, Phys Rev B 85 104520 (2012)

Hague JP, Kornilovitch PE, Samson JH, Alexandrov AS. Superlight small bipolarons. J Phys: Condens Matter 19 225214 (2007)

Samson JH. Phase-space path-integral calculation of the Wigner function, J Phys A 36 10637 (2003)

Samson JH. Spin density wave selection in the one-dimensional Hubbard model, J Phys: Condens Matter 8 569 (1996)

Samson JH. Quantum Monte Carlo Computation: The Sign Problem as a Berry Phase, Phys Rev B 47 3408 (1993)

Chana KS, Samson JH, Luchini MU, Heine V. Magnetic short-range order in iron above Tc – statistical mechanics with many-atom interactions, J Phys: Condens Matter 3 6455 (1991)

  • EPSRC College member
  • Reviewer for CINT
  • Postgraduate Induction
  • Undergraduate Projects
  • Postgraduate Projects