Preservation of atomic coherence in double-well optical lattice in presence of decoherence (2010)
We present a quantum interference approach to preserve coherence in the external states of an atom trapped in an optical lattice. We show that this is possible by suitably choosing the initial state...
Decoherence-induced geometric phase in a multilevel atomic system (2006)
Dasgupta, Shubhrangshu, Lidar, Daniel A.
We consider the STIRAP process in a three-level atom. Viewed as a closed system, no geometric phase is acquired. But in the presence of spontaneous emission and/or collisional relaxation we show...
Two-bit Deutsch-Jozsa algorithm using an atomic ensemble (2006)
Dasgupta, Shubhrangshu, Agarwal, G. S.
The first optical proposal for the realization of the two-bit version of the Deutsch-Jozsa algorithm [D. Deutsch and R. Jozsa, Proc. R. Soc. London A {\bf 493}, 553 (1992)] is presented. The proposal...
Quantum interferences from cross talk in $J=1/2\leftrightarrow J=1/2$ transitions (2005)
We consider the possibility of a control field opening up multiple pathways and thereby leading to new interference and coherence effects. We illustrate the idea by considering the...
Agarwal, G. S., Dasgupta, Shubhrangshu
We calculate magneto-optical rptation of spectrally impure fileds in an optically thick cold atmic medium. We show that the spectral impurity leads to non-linear dependence of the rotation angle on...
Agarwal, G. S., Dasgupta, Shubhrangshu
We show how a medium, under the influece of a coherent control field which is resonant or close to resonance to an appropriate atomic transition, can lead to very strong asymmetries in the...
Coherent medium as a polarization splitter of pulses (2002)
Agarwal, G. S., Dasgupta, Shubhrangshu
We show how one can use the anisotropic properties of a coherent medium to separate temporally the two polarization components of a linearly polarized pulse. This is achieved by applying a control...
Improving the Fidelity of Quantum Cloning by Fast Cycling away the Unwanted Transition (2000)
Dasgupta, Shubhrangshu, Agarwal, G. S.
The fidelity of quantum cloning is very often limited by the accompanying unwanted transitions. We show how the fidelity can be improved by using a coherent field to cycle away the unwanted...