Atomic Fock states and quantum computing

Benjamin T. H. Varcoe

The one atom maser is an archetype experiment of quantum optics, where the interaction is between the basic quantum components of a single atoms and a single mode field, uncluttered by unwanted side effects. Thus the one atom maser is able to examine the most fundamental aspects of the atom light interaction. In this paper we review three of the most recent experiments on the very topical subject of photon Fock state creation. Namely the creation Fock states via trapping states, dynamical Fock state preparation using state reduction of lower state atoms and finally the creation of Fock states on demand. In the two decades since its first operation, the one atom maser continues to operate at the forefront of quantum optics research having produced many first class results. We present some taste of future, as we turn the micromaser to quantum computing and the creation of exotic entangled states.

Alexander A. Berezin

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.

David Medellín, Gabriel Price, Kirsten Viering +2 more

Hrishikesh Kelkar

Benjamin T. H. Varcoe, S. Brattke, HERBERT WALTHER

Many applications in quantum information or quantum computing require radiation with a fixed number of photons (called Fock or number states) and this special issue demonstrates the real increase in interest in this area. In this paper, we review three recent papers in which we discussed the creation of photon number states in the micromaser and discuss new results. In the first experiment, Fock states were created in steady state via trapping states. Some new results are presented in this section showing a remarkable improvement of our ability to create these states. We then review a second method of dynamic Fock state creation using state reduction of lower state atoms. In this experiment, we also observed the purity of the Fock state that was created via the observation of Rabi oscillations of a probe atom. Finally, we discuss the results of the third experiment that we performed which was an experimental demonstration of a method of creating Fock states on demand.