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arXiv:2512.17537 · Physical Review A

Coherent phase control of orbital-angular-momentum light-induced torque in a double-tripod atom-light coupling scheme

Hamid R. Hamedi, Viačeslav Kudriašov, Mažena Mackoit-Sinkevičienė, Julius Ruseckas

quant-phSubmitted Dec 19, 2025• Announced Dec 22, 2025• 1 citation
arXivHTMLPDF

Abstract

We investigate a phase-controllable mechanism for generating optical torque in a five-level double-tripod (DT) atom-light coupling scheme interacting with four strong coherent control fields as well as two weak optical vortex probe beams carrying orbital angular momentum (OAM). The spatial phase gradients of the OAM-carrying probes induce a quantized torque that is transferred to the atoms, rotating them and generating a directed atomic flow within an annular geometry. Analytical solutions of the optical Bloch equations under steady-state conditions show that the induced torque and resulting rotational motion exhibit high sensitivity to phase variations. We show that the DT system coherently reconfigures into either coupled Λ or double-Λ schemes depending on the relative phases, with each configuration exhibiting distinct quantized torque characteristics. This enables precise phase control of the atomic current flow, with potential applications in quantum control, precision measurement, and quantum information processing.

Journal reference
Phys. Rev. A 112, 063720 (2025)
DOI
10.1103/nbx8-l3v4

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We propose a scheme to map atoms via the coherence superpositions of orbital angular momentum (OAM) light. The atoms are prepared in the four-level tripod configuration in the presence of a vortex light, which coherently superposes two Laguerre-Gaussian (LG) beam modes with equal but opposite OAM. Because of the spatially dependent atom-field interaction, the information about the position of the atom can be obtained via the absorption measurement of the weak probe field. It is found that the absorption behavior is significantly impacted by the detuning, control field, azimuthal number, and radial number. Most importantly, atomic mapping accuracy can be controlled by properly adjusting the detunings and control field. The coherent interaction of OAM light with atoms constitutes a platform for active mapping of atoms at specific positions in azimuthal space.