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Two-photon coherent control of a single quantum dot.
T Flissikowski1, A Betke, I A Akimov
1Institut für Physik, Humboldt Universität zu Berlin, Newtonstrasse 15, 12489 Berlin, Germany.
Physical Review Letters
|July 13, 2004
Summary
We demonstrate two-photon coherent control of biexcitons in cadmium selenide quantum dots. Interference patterns reveal environmental fluctuations affecting quantum dot energy levels.
Area of Science:
- Quantum optics
- Solid-state physics
- Materials science
Background:
- Quantum dots are semiconductor nanocrystals with tunable optical properties.
- Biexcitons are pairs of bound excitons, crucial for quantum information applications.
- Coherent control manipulates quantum states using precise laser pulses.
Purpose of the Study:
- To investigate two-photon coherent control of biexciton states in single Stranski-Krastanov CdSe quantum dots.
- To analyze the interference patterns generated by coherent control.
- To understand the factors causing the decay of interference contrast.
Main Methods:
- Utilizing two-photon spectroscopy to excite and control biexciton states.
- Observing interference patterns at twice the optical frequency.
- Analyzing the temporal decay of interference contrast.
Main Results:
- Clear interference patterns were observed, confirming biexciton state control.
- The decay of interference contrast was found to be nonexponential.
- Dynamical inhomogeneous broadening due to environmental fluctuations was identified as the cause.
Conclusions:
- Two-photon coherent control is effective for manipulating biexciton states in CdSe quantum dots.
- Environmental dynamics significantly impact quantum coherence.
- Understanding these dynamics is key for advancing quantum technologies using quantum dots.