Details
| Original language | English |
|---|---|
| Article number | 123052 |
| Pages (from-to) | 123052 |
| Number of pages | 1 |
| Journal | New J. Phys. |
| Volume | 16 |
| Publication status | Published - 19 Dec 2014 |
Abstract
We discuss decoherence in discrete-time quantum walks in terms of a phenomenological model that distinguishes spin and spatial decoherence. We identify the dominating mechanisms that affect quantum-walk experiments realized with neutral atoms walking in an optical lattice. From the measured spatial distributions, we determine with good precision the amount of decoherence per step, which provides a quantitative indication of the quality of our quantum walks. In particular, we find that spin decoherence is the main mechanism responsible for the loss of coherence in our experiment. We also find that the sole observation of ballistic - instead of diffusive - expansion in position space is not a good indicator of the range of coherent delocalization. We provide further physical insight by distinguishing the effects of short- and long-time spin dephasing mechanisms. We introduce the concept of coherence length in the discrete-time quantum walk, which quantifies the range of spatial coherences. Unexpectedly, we find that quasi-stationary dephasing does not modify the local properties of the quantum walk, but instead affects spatial coherences. For a visual representation of decoherence phenomena in phase space, we have developed a formalism based on a discrete analogue of the Wigner function. We show that the effects of spin and spatial decoherence differ dramatically in momentum space.
Keywords
- decoherence, floquet theory, optical lattices, quantum walks
ASJC Scopus subject areas
- Physics and Astronomy(all)
- General Physics and Astronomy
Cite this
- Standard
- Harvard
- Apa
- Vancouver
- BibTeX
- RIS
In: New J. Phys., Vol. 16, 123052, 19.12.2014, p. 123052.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Decoherence Models for Discrete-Time Quantum Walks and their Application to Neutral Atom Experiments
AU - Alberti, A.
AU - Alt, W.
AU - Werner, R. F.
AU - Meschede, D.
N1 - Publisher Copyright: © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. Copyright: Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2014/12/19
Y1 - 2014/12/19
N2 - We discuss decoherence in discrete-time quantum walks in terms of a phenomenological model that distinguishes spin and spatial decoherence. We identify the dominating mechanisms that affect quantum-walk experiments realized with neutral atoms walking in an optical lattice. From the measured spatial distributions, we determine with good precision the amount of decoherence per step, which provides a quantitative indication of the quality of our quantum walks. In particular, we find that spin decoherence is the main mechanism responsible for the loss of coherence in our experiment. We also find that the sole observation of ballistic - instead of diffusive - expansion in position space is not a good indicator of the range of coherent delocalization. We provide further physical insight by distinguishing the effects of short- and long-time spin dephasing mechanisms. We introduce the concept of coherence length in the discrete-time quantum walk, which quantifies the range of spatial coherences. Unexpectedly, we find that quasi-stationary dephasing does not modify the local properties of the quantum walk, but instead affects spatial coherences. For a visual representation of decoherence phenomena in phase space, we have developed a formalism based on a discrete analogue of the Wigner function. We show that the effects of spin and spatial decoherence differ dramatically in momentum space.
AB - We discuss decoherence in discrete-time quantum walks in terms of a phenomenological model that distinguishes spin and spatial decoherence. We identify the dominating mechanisms that affect quantum-walk experiments realized with neutral atoms walking in an optical lattice. From the measured spatial distributions, we determine with good precision the amount of decoherence per step, which provides a quantitative indication of the quality of our quantum walks. In particular, we find that spin decoherence is the main mechanism responsible for the loss of coherence in our experiment. We also find that the sole observation of ballistic - instead of diffusive - expansion in position space is not a good indicator of the range of coherent delocalization. We provide further physical insight by distinguishing the effects of short- and long-time spin dephasing mechanisms. We introduce the concept of coherence length in the discrete-time quantum walk, which quantifies the range of spatial coherences. Unexpectedly, we find that quasi-stationary dephasing does not modify the local properties of the quantum walk, but instead affects spatial coherences. For a visual representation of decoherence phenomena in phase space, we have developed a formalism based on a discrete analogue of the Wigner function. We show that the effects of spin and spatial decoherence differ dramatically in momentum space.
KW - decoherence
KW - floquet theory
KW - optical lattices
KW - quantum walks
UR - http://www.scopus.com/inward/record.url?scp=84920281202&partnerID=8YFLogxK
U2 - 10.1088/1367-2630/16/12/123052
DO - 10.1088/1367-2630/16/12/123052
M3 - Article
VL - 16
SP - 123052
JO - New J. Phys.
JF - New J. Phys.
SN - 1367-2630
M1 - 123052
ER -