Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.

July 27, 2006
12:30 PM

Daniel Lidar,
University of Southern California

Adiabaticity in open quantum systems: theory and applications to adiabatic quantum computation and geometric phases

Abstract

The adiabatic approximation is an 80+ year old pillar of quantum mechanics, which has found rich applications in a variety of physics and chemistry problems. However, in its original formulation the adiabatic theorem was derived in the context of closed quantum systems, described by unitary dynamics. We have recently introduced a generalization of the the adiabatic theorem to open quantum systems described by convolutionless master equations [1]. This version of the adiabatic theorem is naturally suited to problems in quantum information theory, and we describe applications to the adiabatic quantum computing paradigm [2], and to the problem of geometric phases (both Abelian and non-Abelian) in open quantum systems undergoing cyclic adiabatic evolution [3]. One our main findings is that, in general, adiabaticity in an open quantum system depends on two competing timescales: the speed of the driving field and the decoherence due to the interaction with the environment. These timescales generically determine a finite interval for adiabaticity. This has implications for both adiabatic quantum computing and the robustness of geometric phases to decoherence. Joint work with Dr. Marcelo Sarandy.

References:

• ^[1] Adiabatic Approximation in Open Quantum Systems, M.S. Sarandy and D.A. Lidar, Phys. Rev. A 71, 012331 (2005).
• ^[2] Adiabatic Quantum Computation in Open Systems, M.S. Sarandy and D.A. Lidar, Phys. Rev. Lett. 95, 250503 (2005).
• ^[3] Abelian and Non-Abelian Geometric Phases in Adiabatic Open Quantum Systems, M.S. Sarandy and D.A. Lidar, Phys. Rev. A 73, 062101 (2006).