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Decoherence and disorder in quantum walks: from ballistic spread to localization
A Schreiber1, K N Cassemiro, V Potoček
1Max Planck Institute for the Science of Light, Erlangen, Germany. Andreas.Schreiber@mpl.mpg.de
Physical Review Letters
|June 4, 2011
Summary
We explored how decoherence and disorder affect quantum walks. Our photonic experiment demonstrated Anderson localization, a key quantum phenomenon, in a discrete quantum walk architecture.
Area of Science:
- Quantum physics
- Condensed matter physics
- Photonics
Background:
- Quantum walks are essential for quantum computation and simulating quantum systems.
- Understanding environmental impacts like decoherence and disorder is crucial for robust quantum simulations.
- Previous studies have explored quantum walks, but experimental realization of Anderson localization in discrete architectures is novel.
Purpose of the Study:
- To investigate the effects of decoherence and static disorder on quantum particle dynamics in a periodic lattice.
- To experimentally demonstrate Anderson localization in a discrete quantum walk.
- To compare different environmental influences on quantum walk evolution.
Main Methods:
- Utilizing a photonic implementation of a one-dimensional discrete quantum walk.
- Characterizing pure quantum evolution via ballistic spread of a photon's wave packet over 28 steps.
- Simulating environmental influences (decoherence, disorder) using controlled time-dependent operations.
Main Results:
- Pure quantum evolution showed ballistic spread.
- Simulated decoherence led to a fast ballistic spread.
- Simulated static disorder induced a diffusive classical walk.
- Achieved the first experimental observation of Anderson localization in a discrete quantum walk.
Conclusions:
- Decoherence accelerates quantum walk spread.
- Static disorder drives quantum walks towards classical diffusive behavior.
- Discrete quantum walks provide a viable platform for observing Anderson localization and studying quantum transport phenomena.
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