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Q: Fachverband Quantenoptik und Photonik
Q 63: Quanteninformation: Quantencomputer
Q 63.6: Talk
Friday, March 6, 2009, 15:15–15:30, VMP 6 HS-A
Measurement-Based Quantum Computation in Realistic Spin-1 Chains — •Joseph M. Renes1, Gavin Brennen2, Stephen D. Bartlett3, and Akimasa Miyake4 — 1TU Darmstadt, Germany — 2Macquarie University, Sydney, Australia — 3University of Sydney, Sydney, Australia — 4Perimeter Institute, Waterloo, Canada
We study the measurement-based computational abilities of ground states of spin-1 chains near the AKLT point, as recently proposed by Brennen and Miyake [1]. In this hybrid scheme individual qubit gates are performed by measurement while two-qubit gates are performed by dynamically coupling different chains. The gapped spectrum of the chains is expected to help suppress decoherence in realistic implementations, such as atoms or polar molecules in optical lattices. We show that the approach taken by Doherty and Bartlett to characterize the computational power of nearly-cluster state quantum computers [2] can be profitably adapted to this case, avoiding the need to keep track of the exponentially-many computational paths. Numerical analysis shows that arbitrary single-qubit operations can be faithfully executed over a reasonably wide parameter range of bilinear-biquadratic Hamiltonians near the AKLT point. Furthermore, we find that the Doherty-Bartlett approach leads directly to the use of string order parameters, showing a connection between computational questions and the traditional theoretical study of condensed matter, where these parameters arise.
[1] Brennen and Miyake, Phys. Rev. Lett. 101, 010502 (2008). [2] Doherty and Bartlett, arXiv:0802.4314v1 [quant-ph].