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Ehrenfest time and the coherent backscattering off ballistic cavities
1Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.
Physical Review Letters
|June 29, 2006
Summary
Weak localization in ballistic cavities is suppressed when Ehrenfest time is comparable to dwell time. Enhanced backscattering occurs regardless of Ehrenfest time, with new off-diagonal contributions appearing when Ehrenfest time equals dwell time.
Area of Science:
- Quantum transport phenomena
- Mesoscopic physics
- Wave interference in cavities
Background:
- Weak localization corrections to transmission in ballistic cavities are sensitive to the Ehrenfest time (τ(E)) relative to the dwell time (τ(D)).
- Quantum interference leads to enhanced backscattering, a phenomenon independent of the Ehrenfest time.
- Understanding these effects is crucial for designing and analyzing quantum devices.
Purpose of the Study:
- To investigate the interplay between Ehrenfest time and dwell time on weak localization and backscattering in ballistic cavities.
- To identify and characterize new contributions to coherent backscattering beyond the standard enhanced backscattering.
- To determine the conditions under which off-diagonal coherent backscattering becomes significant.
Main Methods:
- Theoretical analysis of quantum transport in ballistic cavities.
- Calculation of weak localization corrections to transmission.
- Investigation of quantum interference effects on reflection and backscattering probabilities.
- Derivation of expressions for diagonal and off-diagonal coherent backscattering contributions.
Main Results:
- Weak localization correction is suppressed exponentially with the ratio of Ehrenfest time to dwell time (exp(-τ(E)/τ(D))).
- Enhanced backscattering, a factor of two increase in reflection probability into the incident mode, is independent of the Ehrenfest time.
- Off-diagonal contributions to coherent backscattering emerge and become relevant when the Ehrenfest time is greater than or equal to the dwell time (τ(E) ≥ τ(D)).
Conclusions:
- The Ehrenfest time plays a critical role in suppressing weak localization corrections in ballistic cavities.
- Enhanced backscattering is a robust quantum interference effect, but its underlying mechanisms are modified by the Ehrenfest time.
- The emergence of off-diagonal coherent backscattering at τ(E) ≥ τ(D) reveals a more complex interference scenario than previously understood, impacting cavity dynamics.
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