Dr Dan Browne (University College London)

 Prof Terry Rudolph (Imperial College London)

 Prof Jeremy O'Brien (University of Bristol)

Optical Quantum Computation

Computers are a very trusted tool in most fields of research, and yet there are many problems that due to their complexity cannot be addressed effiently. Quantum computation is a new paradigm of computation that exploits the non-classical features of quantum systems. A quantum computer is a machine that once encoding has been made, would take advantage of all the complexity of the many-particle quantum wavefunction to solve a computational problem. It will certainly not replace the classical computers sitting on our desks but will open the possibilities of performing computations we wouldn't be able to do efficiently otherwise. The authors of a recent review on the field of Quantum Computers believe that the advent of a quantum computer will have a similar impact to the one of the laser . The laser provides us with many technological advances but it certainly hasn't replaced light bulbs.

There are several models for quantum computation as well a very diferent technologies in which a quantum computer could be implemented. On this project, we focus on the combination of the computation model of measurement-based quantum computation with on-chip photonic systems. The advantage of this model of computation is that the entire resource with all its non-classical features is prepared offline, so that the computation is done by single-qubit measurements reducing the risk of the computation going wrong. Photonic systems are very promising as the technology for the implementation of this model as they have low-noise properties and high speed transmission. There has been work showing how photons can implement cluster state computation and our aim is to extend this work and address all the considerations needed for a blueprint of an optical quantum computer.


with Pete Shadbolt, Dan E. Browne and Terry Rudolph, October 2014 (arXiv:1410.3720)


  • Efficient construction of a linear optical cluster state 

         PICQUE Workshop, University of Oxford, January 2015

  • From three-photon GHZ states to universal ballistic quantum computation

        University of Science and Technology of China, November 2014

  • Resource-efficient construction of a linear optical cluster state 

         IQOQI, University of Innsbruck, Austria, May 2014

  • Simulation of stabilizer circuits

          invited lecture for Advanced Quantum Information course of the CQD DTC MRes, March 2014

  • Building an optical quantum computer 

          Seminar at Departamento de Física Teórica I, Facultad de CC. Físicas, UCM , May 2013

  • Simulation of stabilizer circuits

         UCL QCumber 2013, Quantum Technologies Programme, Cumberland Lodge, April 2013

  • Building an optical quantum computer 

         Quantum Square, Student Conference on mathematical and theoretical aspects of Quantum Mechanics,              University of Nottingham November 2012


  • From three-photon GHZ states to universal ballistic quantum computation

         QEC14, Zurich, December 2014

  • Resource-efficient construction of a linear optical cluster state.

         International Iran Conference on Quantum Information 2014, Isfahan, September 2014

        12th Intl.. Conference on Quantum Communication, Measurement and Computing, Hefei,                                November 2014

  • Improving photonic GHZ ballistic generation with boosted fusion gates.

         IOP Photon14 conference, London, September 2014

  • A GHZ factory on a chip

         Summer School on Quantum Information, Computing and Control, Aberystwyth, August 2012

Outreach activities

            More House School, London, October 2014

           Imperial College, London, June 2014


           Imperial College, London, June 2014

  • Show: "The Qua ntum Showcase"  

           Imperial Festival, Imperial College London, May 2014

  • Talks: "How I became a scientist" and "Quantum Technologies in our everyday life" 

           Bacons College, London, March 2014

          St Marylebone School, London, December 2013

  • Talk:  Quantum Physics in our everyday life

         part of the A level STEM day at Kingsbury High School , London, September 2013

  • Talk:  Tecnologías cuánticas (Quantum technologies)

       Colegio Sagrado Corazón de Jesús , Madrid, May 2013

   with CQD CDT at ExCeL, March 2013

  • Talk:  Women in Science

        with Fern Watson,  Henrietta Barnett School, London, December 2012

  • Workshop:  INSPIRE teacher workshop

        with members of DTC CQD,  Imperial college, London, November 2012

  • Talk:  Quantum

      Henrietta Barnett School, London, October 2012

  • Science Busking at Imperial Festival

       with CQD CDT  at Imperial College London, May 2012

  • Show: Oddities of Physics

   with CQD CDT Cohort 3 , Imperial College London, January 2012