Stimulated raman adiabatic passage

The Stimulated Raman adiabatic passage (STIRAP) process permits transfer of a population between two applicable quantum states via at least two coherent electromagnetic (light) pulses. These light pulses drive the transitions of the three level Ʌ atom or multilevel system.^[1]^[2] The process is a form of state-to-state coherent control.

Population transfer in three level Ʌ atom

Consider the description of three level Ʌ atom having ground state $|g_1\rangle$ and $|g_2\rangle$ (for simplicity consider the energy of both ground states are same) and excited state $|e\rangle$ respectively. Suppose in the beginning the total population is in the ground state $|g_1\rangle$ . Here the logic for transformation of the population from ground state $|g_1\rangle$ to $|g_2\rangle$ is that initially the unpopulated states $|g_2\rangle$ and $|e\rangle$ couple, afterward superposition of state $|g_2\rangle$ and $|e\rangle$ couple to the state $|g_1\rangle$ . Thereby a state is formed that permits the transformation of the population into state $|g_2\rangle$ without populating the excited state $|e\rangle$ . This process of transforming the population without populating the excited state is called the stimulated Raman adiabatic passage.^[3]

References

↑ Unanyan, R., M. Fleischhauer, B. W. Shore, and K. Bergmann. "Robust creation and phase-sensitive probing of superposition states via stimulated Raman adiabatic passage (STIRAP) with degenerate dark states." Optics communications 155, no. 1 (1998): 144-154.
↑ Schwager, Heike (2008). A quantum memory for light in nuclear spin of quantum dot. Max-Planck-Institute of Quantum Optics.
↑ P. Marte, P. Zoller, J.L.Hall. "Quantum state-mapping between multi-level atoms and cavity light fields, Phys. Rev A44 , 1991".