|
Search... |
Quantum and Condensed Matter Physics Research in a broad range of topics in quantum and condensed matter physics is carried out by Professors Miles Blencowe, Walter Lawrence, and Lorenza Viola (theory), and Alexander Rimberg (experimental). Theory Professor Blencowe's current research interests are primarily within the area of mesoscopic physics, with a focus on the dynamics of nano-to-mesoscale quantum electromechanical systems. A fundamental motivation is to understand the transition from quantum to classical physics for non-trivial dynamical systems. Prof. Blencowe has active collaborations with researchers at Cornell University, Technion (Israel), and the University of Nottingham (UK). Professor Lawrence is exploring practical and foundational aspects of quantum information theory. A current focus is the study of alternative operator bases relevant to quantum tomography, such as mutually unbiased measurements and Pauli operators. These bases are being studied particularly for systems of many qubits and many qutrits, although the comparison to continuous systems raises interesting questions for possible future investigation. In a different direction, we have studied decohering effects of the environment on decaying metastable quantum systems. The ultimate goal of this work is to better understand the evolution of a quantum system in contact with an environment and subject to measurement. Prof. Viola's current research focuses on various theoretical and phenomenological aspect of quantum information physics. A main goal is the development of strategies for controlling realistic open quantum systems. Special emphasis is devoted to schemes for reliable quantum information processing, including dynamical decoupling techniques, noiseless subsystems, and quantum error correcting codes. Another broad research direction is to explore the significance of quantum information theory to better understand 'complex' quantum behavior, including entanglement, quantum randomness, and quantum chaos. More information about Prof. Viola's research is available on her group's web site. 
Quantum network for protecting a logical qubit in a noiseless subsystem supported by three physical qubits. A noiseless subsystem relies on the occurrence of symmetries in the error process: these symmetries lead to conserved quantities which, under the appropriate conditions, may be used to construct error-free logical qubits. Here, the applied noise has permutation symmetry. The information is initially stored in qubit 3, whereas qubits 1 and 2 are used as ancillae to effect the encoding and decoding transformations that map the information to the protected degree of freedom, and back. Even if the state of the system as a whole is corrupted by noise, information stored in the noiseless subsystem is recovered in qubit 2 after decoding. This idea was experimentally demonstrated using a liquid-state NMR quantum information processor [Viola et al, Science 293, 2059 (2001)]. Experiment Prof. Rimberg's research focuses on use of radio-frequency and microwave techniques to investigate the dynamics of electrons in such nanostructures as quantum dots and single-electron transistors. This includes use of real-time detection of electron tunneling to study fundamental issues of quantum mechanics and quantum measurement. Particular areas of investigation include use of spin in semiconductor quantum dots for quantum information processing, study of temporal electronic correlations in nanoscale devices, and investigation of the quantum limits of amplifiers. The group has active collaborations with the University of Wisconsin, NIST Boulder and Bell Laboratories. More information about Prof. Rimberg's research is available on his group's web site.
Recent Publications "Measurement of Quantum Noise in a Single Electron Transistor Near the Quantum Limit," W. W. Xue, Z. Ji, F. Pan, J. Stettenheim, M. P. Blencowe and A. J. Rimberg, Nature Phys. 5, 660 (2009). "On-Chip Matching Networks for Radio-Frequency Single-Electron Transistors," Wei Wei Xue, B. Davis, Feng Pan, J. Stettenheim, T. J. Gilheart, A. J. Rimberg and Z. Ji, Appl. Phys. Lett. 91, 093511 (2007) P.D. Nation, M.P. Blencowe, A. J. Rimberg, and E. Buks, "Analogue Hawking Radiation in a dc-SQUID Array Transmission Line," Phys. Rev. Lett 103, 087004 (2009) P.D. Nation, M.P. Blencowe, and E. Buks, "Quantum Analysis of a Nonlinear Microwave Cavity-Embedded DC SQUID Displacement Detector," Phys. Rev. B 78, 104516 (2008) W.E. Lawrence, "Rotational properties and GHZ contradictions in N-Qubit systems," quant-ph/0506063 (7 June 2005) W.E. Lawrence, M.N. Wybourne, and S.M. Carr, "Compressional mode softening and Euler buckling patterns in mesoscopic beams," New Journal of Physics 8, 223 (2006). K. Khodjasteh and L. Viola, "Dynamically error-corrected gates for universal quantum computation," Phys. Rev. Lett. 102, 080501 (2009). S. Deng, G. Ortiz, and L. Viola, "Dynamical non-ergodic scaling in continuous finite-order quantum phase transitions," Europhys. Lett. 84, 67008 (2008). R. Blume-Kohout, H. K. Ng, D. Poulin, and L. Viola, "Characterizing the structure of preserved information in quantum processes," Phys. Rev. Lett. 100, 030501 (2008). |
