Realization of the quantum Toffoli gate based on a six-level atomic system

Author(s):  
A. Chouikh ◽  
T. Said ◽  
M. Hammani ◽  
M. Bennai

In this paper, we propose a scheme for implementing a Toffoli gate in a system with an atom that has six levels in a lambda configuration, interacting with a high-Q cavity containing four modes. Here, we reduce a six-level system into an effective three-level behavior by applying the adiabatic elimination method. Next, we calculate the probabilities of the states of the interest as well as the fidelity. We also study the effects of photonic and atomic decay rates on the evolution of the system which is reasonably less sensitive to decoherence.

2013 ◽  
Vol 816-817 ◽  
pp. 242-245
Author(s):  
Xiang An Yan ◽  
Li Qiang Wang

We propose a scheme for realizing negative refractive index in a multilevel atomic system. The theoretical modeling has been done using density matrix approach in which the spontaneously generated coherence (SGC) is also induced. It is shown that the negative refractive index can be obtained on the effect of quantum coherence. The parameters () quantifying left-handedness in the system become more negative if the SGC is defined in the appropriate value. Furthermore, left-handed material with reduced absorption is possible by choosing appropriate parameters.


2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
Yingjie Du ◽  
Kang Jin ◽  
Junxiang Zhang

The Kerr nonlinearity is investigated in an N-type four-level atomic system whose both supper levels are degenerated or nearly degenerate. It is found that the spontaneously generated coherence as a result of the degenerate levels can change the Kerr nonlinearity dramatically depending on the angle between two spontaneous channels. In addition, we discover that the probe field makes its own contribution to the nonlinearity in comparison to indifference in general three-level systems.


2005 ◽  
Vol 254 (1-3) ◽  
pp. 76-87 ◽  
Author(s):  
M.M.A. Ahmed ◽  
E.M. Khalil ◽  
A.-S.F. Obada

2006 ◽  
Vol 53 (8) ◽  
pp. 1149-1163 ◽  
Author(s):  
A.-S. F. Obada ◽  
E. M. Khalil ◽  
M. M. A. Ahmed

2021 ◽  
Author(s):  
Zeeshan Ali Safdar Jadoon ◽  
Heung-Ryoul Noh ◽  
Jin-Tae Kim

Abstract Optical Bloch equations with and without neighboring hyperfine states near the degenerate two-level system (DTLS) in the challenging case of 85Rb D2 transition that involves the Doppler broadening effect are solved herein. The calculated spectra agree well with the experimental results obtained using the coupling-probe scheme with orthogonal linear polarizations of the coupling and probe fields. The mechanisms of electromagnetically induced absorption (electromagnetically induced transparency) for the open Fg = 3 → Fe = 2 and 3 transitions (open Fg = 2 → Fe = 2 and 3 transitions) are clearly determined to be the effect of the strong closed Fg = 3 → Fe = 4 transition line (strong closed Fg = 2 → Fe = 1 transition line) based on the comparisons of the calculated absorption profiles of a DTLS without neighboring states and those of all levels with neighboring states depending on the coupling and probe power ratios. The crucial factors established based on comparisons of the calculated absorption profiles of DTLS with and without neighboring states, which enhance or reduce coherence effects and result in transformation between electromagnetically induced absorption and electromagnetically induced transparency, are the power ratios between coupling and probe beams, openness of the excited state, and effects of the neighboring states due to the Doppler broadening in a real atomic system.


2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Zeeshan Ali Safdar Jadoon ◽  
Heung-Ryoul Noh ◽  
Jin-Tae Kim

AbstractIn this study, optical Bloch equations with and without neighboring hyperfine states near the degenerate two-level system (DTLS) in the challenging case of $$^{85}$$ 85 Rb D2 transition, which involves the Doppler broadening effect, are solved. The calculated spectra agree well with the experimental results obtained based on the coupling-probe scheme with orthogonal linear polarizations of the coupling and probe fields. The mechanisms of electromagnetically induced absorption (electromagnetically induced transparency) for the open $$F_g=3 \rightarrow F_e=2$$ F g = 3 → F e = 2 and 3 transitions (open $$F_g=2 \rightarrow F_e=2$$ F g = 2 → F e = 2 and 3 transitions) are determined to be the effect of the strong closed $$F_g=3 \rightarrow F_e=4$$ F g = 3 → F e = 4 transition line (strong closed $$F_g=2 \rightarrow F_e=1$$ F g = 2 → F e = 1 transition line); this finding is based on a comparison between the calculated absorption profiles of the DTLS without neighboring states and those of all levels with neighboring states, depending on the coupling and probe power ratios. Furthermore, based on the aforementioned comparison, the crucial factors that enhance or reduce the coherence effects and lead to the transformation between electromagnetically induced absorption and electromagnetically induced transparency, are (1) the power ratios between the coupling and probe beams, (2) the openness of the excited state, and (3) effects of the neighboring states due to Doppler broadening in a real atomic system.


2007 ◽  
Vol 32 (2-3) ◽  
pp. 123-126
Author(s):  
Y.-R. Nowicki-Bringuier ◽  
J. Claudon ◽  
C. Böckler ◽  
S. Reitzenstein ◽  
M. Kamp ◽  
...  

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