People

Bill Munro
Principal Research Scientist

E-mail: bill.munro@hp.com
Phone: +44 (0)117 312 7012
FAX: +44 (0)117 312 9870

Location:
Quantum Information Processing Group
Hewlett-Packard Laboratories, Bristol

Bill graduated in 1989 with a BSc in Chemistry and Physics (Waikato, New Zealand), followed by an MSc in Physics (Waikato) in 1991 and a Dphil in Quantum Optics (Waikato) in 1994. He moved to the computer industry in early 1995 where he worked on various projects. In July 1997 he accepted an Australian Research Council Fellowship at the Department of Physics in the University of Queensland, Australia. During this fellowship he investigated multiparticle tests of quantum mechanics and developed an interest in entanglement, methods to characterise it and its practical use in QIP. In 2000 he became a senior researcher in the Australian Special Centre for Quantum Information Processing). In November 2000 Bill joined HP Labs as a research scientist.

Bill has researched and published extensively in several areas of Physics; from foundational issues of quantum theory, quantum and atom optics through to quantum information processing and quantum state and process tomography, decoherence free subspaces and their application to practical QIP. His current interests have focussed around:

• Quantum Information Processing and Computation
• The practical implementation for optical and solid state quantum hardware
• Optical Information  Processing including linear optical and weak nonlinearity
• The characterisation of quantum states and processes
• Short range quantum key distribution and potential applications
• High precision measurements and quantum metrology
   

Two of the areas he has been particularly involved with include:

1. Qubus Computation:  We have developed a radically new approach to scalable quantum computing - a "qubus computer" - which realises qubit measurement and quantum gates through interacting qubits with a quantum communication bus mode.  The qubits can be "static" matter qubits or "flying" optical qubits.  There is no requirement for direct interaction between the qubits.  Universal two-qubit quantum gates may be affected by schemes which involve measurement of the bus mode, or by schemes where the bus disentangles automatically and no measurement is needed.  In effect, the approach integrates together qubit degrees of freedom for computation with quantum continuous variables for communication and interaction.
    
2. A hybrid quantum repeater using bright coherent light: Here we proposed a quantum repeater protocol for long-distance quantum communication. In this scheme, entanglement is created between qubits at intermediate stations of the channel by using a weak dispersive light-matter interaction and distributing the outgoing bright coherent light pulses among the stations. Noisy entangled pairs of electronic spin are then prepared with high success probability via homodyne detection and post selection. The local gates for entanglement purification and swapping are deterministic and measurement-free, based upon the same coherent-light resources and weak interactions as for the initial entanglement distribution. With our system, qubit-communication rates approaching 100~Hz over 1280~km with fidelities near 99% are possible for reasonable local gate.
   
   Several interesting recent publications include:
   
   - P. Kok, W. J. Munro, Kae Nemoto, T. C. Ralph, J. P. Dowling and G. J.
   Milburn, Linear optical quantum computing, in press RMP (2006)
   
   - P. van Loock, T. D. Ladd, K. Sanaka, F. Yamaguchi, Kae Nemoto, W. J.
   Munro, and Y. Yamamoto, Hybrid quantum repeater using bright coherent light, Phys. Rev. Lett. 96, 240501 (2006)
   
   - Fumiko Yamaguchi, Kae Nemoto and William J. Munro, Quantum error correction via robust probe modes, Phys. Rev. A 73, 060302R (2006)
   
   -T. P. Spiller, Kae Nemoto, Samuel L. Braunstein, W. J. Munro, P. van Loock and G. J. Milburn, Quantum Computation by Communication, New J.
   Phys. 8, 30 (2006)
   
   - Peter P. Rohde, Timothy C. Ralph and William J. Munro, Practical limitations in optical entanglement purification, Phys. Rev. A 73,
   030301(R) (2006)
   
   - T P Spiller and W J Munro, Towards a Quantum Information Technology Industry, J. Phys.: Condens. Matter 18, 1 (2006).
   
   - W. J. Munro, K. Nemoto and T. P. Spiller, Weak nonlinearities: a new route to optical quantum computation, New J. Phys. 7, 137 (2005).
   
   - T. P. Spiller, W. J. Munro, S. D. Barrett and P.Kok, An introduction to quantum information porcessing: applications and realisations, Comptemporary Physics 46, 407 (2005).
   
   - W. J. Munro, K. Nemoto, R. G. Beausoleil, and T. P. Spiller, A high-efficiency quantum non-demolition single photon number resolving detector, Phys. Rev. A 71, 033819 (2005)
   
   - Kae Nemoto and W. J. Munro, A near deterministic linear optical CNOT gate, Phys. Rev. Lett 93, 250502 (2004)
   
   - John H. Reina, Ray G. Beausoleil, Tim P. Spiller, and William J.
   Munro, Radiative Corrections and Quantum Gates in Molecular Systems, Phys. Rev. Lett 93, 250501
   
   - T.C. Ralph, A. Gilchrist, G.J. Milburn, W.J. Munro and S. Glancy, Quantum computation with optical coherent states, Phys. Rev. A 68,
   042319 (2003)
   
   - Stephen D. Bartlett and William J. Munro, Quantum Teleportation of Optical Quantum Gates, Phys. Rev. Lett. 90, 117901 (2003);
   
   - W.J.Munro, K.Nemoto, G.J.Milburn and S.L.Braunstein, Weak force detection with superposed coherent states, Phys. Rev. A 66, 023819 (2002)
   
   - D. F. V. James, P. G. Kwiat, W.~J. Munro and A. G. White, On the Measurement of Qubits, Phys. Rev. A 64, 052312 (2001)