New and Enhanced Capabilities in Quantum Information Processing (2009-2011)

Working at the intersection of information science and quantum physics, we address the important question of identifying the origin of the power of quantum computing. Most physicists believe that entanglement is key, but much remains to be understood. Our goal is to gain additional insight and understanding of this key issue. In pursuit of this goal, we are investigating network quantum information theory, quantum conditional information, and their roles in understanding and computational modeling of complex quantum systems. Another challenge for quantum information processing is to develop quantum algorithms for problems whose computational complexity renders them insoluble on classical hardware. In this project, we seek new quantum algorithms for an important class of problems in the mathematical theory of knots.

We are also investigating the emerging field of quantum sensing. Here the goal is to find ways to build instruments with sensitivities to forces, accelerations, and electromagnetic fields which exceeds the standard limits due to shot noise, etc. Tasks include the theoretical issue of devising optimum measurement strategies, and the practical challenge of implementing those strategies on suitable quantum hardware, such as trapped ions or ultra-cold atoms.

Finally, we are building a coalition to work at the fertile overlap of atomic and optical physics, quantum information science, and condensed matter physics. Here we aim to devise new techniques for computing quantum systems in the face of exponential complexity, as well as to link the very clean quantum phase transitions observed in ultra-cold gases to the quantum critical behavior which is important in many materials, such as unconventional superconductors.

Focus Areas

• Quantum Computing
• Quantum Cryptography
• Quantum Sensing

Highlight Publications

• Brandao, F., M. Christandl, and J. Yard. Faithful squashed entanglement. 2011.Communications in Mathematical Physics. 306: 805.
• Cooper, F., C. C. Chien, B. Mihaila, J. F. Dawson, and E. Timmermans. Nonperturbative predictions for cold atom bose gases with tunable interactions. 2010. Physical Review Letters. 105: 240402.
• Dziarmaga, J. and Rams, M. Adiabatic Dynamics of an Inhomogeneous Quantum Phase Transition: The Case of a z>l Dynamical Exponent. 2010. New Journal of Physics 12: 103002.
• Dalvit, D., Milonni, P., Roberts, D., and de Rosa, F. (Editors), Lecture Notes in Physics: Casimir Physics. 2011.
• Kato, Y., Martin, I. and Batista, C.D. Stability of spontaneous quantum Hall state in the triangular Kondo lattice model. 2010. Physical Review Letters105: 266405.
• Quan, H. T., and Zurek, W.H.. Testing quantum adiabicity with quench echo. 2010. New Journal of Physics. 12: 093025.
• Smith, G., J. Smolin, and J. Yard. Quantum communication with Gaussian channels of zero capacity. 2011. Nature Photonics. 5: 624.
• Sykes, A.G., Davis, M.J., and Roberts, D.C.. Drag Force on an Impurity Below the Superfluid Critical Velocity in a Quasi-One-Dimensional Bose-Einstein Condensate. 2009. Physical Review Letters 103: 085302.
• Yard, J., and Devetak, I. Optimal quantum source coding with quantum side information at the encoder and decoder. 2009. IEEE Transactions on Information Theory. 55: 5339.