Transformation of coherent states of electromagnetic field to quasi-Fock states

Ardiley Torres Avelar, T. M. Rocha Filho, L. Losano +1 more

Jan Peřina

Valentine I. Zakharov

The possibility of a practically total reduction of quantum photon fluctuations in cw laser radiation is discussed. This effect appears as a result of two-photon radiation absorption using a resonance transition in atoms excited from the ground state to the upper level, relaxing to the other states. For this case the possibility of induced two-photon emission is excluded, that is, the source of additional photon number fluctuations in a field mode.1 In this process the Fock states with the photon number n ≥ 2 are continuously reduced from the coherent state of the excited field. For the large time values of interaction the Fock states |n = 0 > and |n = 1> remain in the field. The effect of spin orientations of photons of the excited field on the quantum noise reduction process for the two-photon absorption by atoms on the transitions between the S → S and S → D terms is analyzed. The possibility of transformation of coherent and thermal fields (λ ≃ 6022 Å and λ = 5787 Å) into quasi-Fock states, as a result of its two-photon resonance absorption by Na homogeneous vapor, is considered.

Jan Peřina

Kiyoung Cho, CHULMIN CHOI, Hoonsoo Kang

Abstract The Fock state is widely regarded as the most nonclassical quantum state of light and has great potential in the areas of quantum computation and quantum sensing. Numerous methods have been proposed to generate Fock states and extremely number-squeezed states, or quasi-Fock states. To utilize natural light for quantum technologies, it is necessary to develop methods for transforming classical light into quasi-Fock states. Thus, we demonstrated that through the collective interaction of light and atoms in the Tavis–Cummings model, we can amplify classical light, such as thermal states and coherent states, and transform those states into quasi-Fock states. To analyze this process, we introduce theoretical tools for studying number state–multi-atom interactions and provide a comprehensive analysis of Tavis–Cummings dynamics, rather than relying on extensions of the Jaynes–Cummings model. Our results reveal that the emergence of nearly sinusoidal emission-absorption oscillations, periodic oscillation of photon number variance, and intrinsic nonlinear effects collectively establishes the necessary condition for deterministic conversion of classical light into quasi-Fock states.

Mariano Uria, Pablo Solano, Carla Hermann-Avigliano

We present a protocol to deterministically prepare the electromagnetic field in a large photon number state. The field starts in a coherent state and, through resonant interaction with one or few two-level systems, it evolves into a coherently displaced Fock state without any postselection. We show the feasibility of the scheme under realistic parameters. The presented method opens a door to reach Fock states, with n∼100 and optimal fidelities above 70%, blurring the line between macroscopic and quantum states of the field.