Abstract We show that rotation can strongly amplify the photonic spin Hall effect in a ring Bose–Einstein condensate. For an incident probe beam carrying orbital angular momentum (OAM), the spin-dependent transverse shift of the reflected light is weak in the non-rotating regime but becomes strongly enhanced under rotation because rotation lifts the degeneracy of the condensate mechanical modes via Bragg scattering. The resulting mode splitting produces large photonic spin Hall shifts at ultra-low optical power, with the enhancement increasing with both the condensate winding number L p and the probe OAM l , while remaining weakly affected by atom–atom interactions. Our findings elucidate a rotation-governed mechanism underlying spin-dependent light transport in hybrid atom–optomechanical systems, thereby highlighting its potential for applications in high-precision rotational sensing.
Abstract We show that rotation can strongly amplify the photonic spin Hall effect in a ring Bose–Einstein condensate. For an incident probe beam carrying orbital angular momentum (OAM), the spin-dependent transverse shift of the reflected light is weak in the non-rotating regime but becomes strongly enhanced under rotation because rotation lifts the degeneracy of the condensate mechanical modes via Bragg scattering. The resulting mode splitting produces large photonic spin Hall shifts at ultra-low optical power, with the enhancement increasing with both the condensate winding number L p and the probe OAM l , while remaining weakly affected by atom–atom interactions. Our findings elucidate a rotation-governed mechanism underlying spin-dependent light transport in hybrid atom–optomechanical systems, thereby highlighting its potential for applications in high-precision rotational sensing.
We present a theoretical investigation of spin-orbit photonics within a fixed mirror cavity system containing a Bose-Einstein condensate (BEC), in which the Bogoliubov excitation modes of the condensate are treated as effective mechanical oscillators. By embedding the condensate in a single-mode optical cavity, we explore the emergence and modulation of the photonic spin Hall effect (PSHE) through the spin-dependent transverse shifts of a weak probe field. The optical response —encoded in the real and imaginary components of the output field susceptibility— is systematically analyzed as a function of the condensate-cavity coupling strength, revealing a controllable enhancement or suppression of the spin-orbit interaction. Our model captures how the interplay between collective BEC excitations and cavity photon dynamics induces nontrivial modifications in spin-dependent light propagation. Notably, we uncover that the Bogoliubov mode coupling acts as a tunable channel for mediating spin angular momentum transfer within the cavity, offering a novel route for engineering compact, quantum-coherent spin-orbit photonic devices.
Recently, a method has been proposed to detect the rotation of a ring Bose-Einstein condensate, , in real-time, and with minimal destruction by using a cavity driven with optical fields carrying orbital angular momentum []. This method is sensitive to the magnitude of the condensate winding number but not its sign. In the present work, we consider simulations of the rotation of the angular lattice formed by the optical fields and show that the resulting cavity transmission spectra are sensitive to the sign of the condensate winding number. We demonstrate the minimally destructive technique on persistent current rotational eigenstates, counter-rotating superpositions, and a soliton singly or in collision with a second soliton. Conversely, we also investigate the sensitivity of the ring condensate, given knowledge of its winding number, to the rotation of the optical lattice. This characterizes the effectiveness of the optomechanical configuration as a laboratory rotation sensor. Our results are important to studies of rotating ring condensates used in atomtronics, superfluid hydrodynamics, simulation of topological defects and cosmological theories, interferometry using matter-wave solitons, and optomechanical sensing. Published by the American Physical Society 2024
In the photonic spin Hall effect (SHE), also known as the transverse shift, incident light photons with opposite spins are spatially separated in the transverse direction due to the spin-orbit interaction of light. Here, we propose a gain-assisted model to control the SHE in the reflected probe light. In this model, a probe light is incident on a cavity containing a three-level dilute gaseous atomic medium, where the interaction between the atom and the control field follows two-photon Raman transitions. We show that the direction of photonic spin accumulations can be switched between positive and negative values across the Brewster angle in both the anomalous and normal dispersion regimes. For the same magnitude of control fields, the peak value of the photonic SHE is higher in the anomalous dispersion region compared to the normal dispersion regime. Additionally, the angular range around the Brewster angle is wider in the normal dispersion regime than in the anomalous dispersion region. Furthermore, the peak value of the photonic SHE and the angular range can be controlled by changing the Rabi frequencies of the control fields and the probe field detuning. The measurement of photonic SHE based on gain assistance may enable spin-related applications such as optical sensing.
We introduce a hybrid optomechanical system containing an annularly trapped Bose-Einstein condensate (BEC) inside an optical cavity driven by Lauguerre-Gaussian (LG) modes. Spiral phase elements serve as the end mirrors of the cavity such that the rear mirror oscillates torsionally about the cavity axis through a clamped support. As described earlier in a related system [P. Kumar , ], the condensate atoms interact with the optical cavity modes carrying orbital angular momentum which create two atomic side modes. We observe three peaks in the output noise spectrum corresponding to the atomic side modes and rotating mirror frequencies, respectively. We find that the trapped BEC's rotation reduces quantum fluctuations at the mirror's resonance frequency. We also find that the atomic side modes-cavity coupling and the optorotational coupling can produce bipartite and tripartite entanglements between various constituents of our hybrid system. We reduce the frequency difference between the side modes and the mirror by tuning the drive field's topological charge and the condensate atoms' rotation. When the atomic side modes become degenerate with the mirror, the stationary entanglement between the cavity and the mirror mode diminishes due to the suppression of cooling. Our proposal, which combines atomic superfluid circulation with mechanical rotation, provides a versatile platform for reducing quantum fluctuations and producing macroscopic entanglement with experimentally realizable parameters. Published by the American Physical Society 2024
We propose a tabletop experiment to generate high-dimensional orbital angular momentum (OAM)-entangled photon pairs using slow-light polaritons in a rotating Bose-Einstein condensate (BEC) containing a giant quantum vortex. By leveraging electromagnetically induced transparency (EIT) to reduce the effective propagation speed and vortex-induced frame dragging to create an analog rotating spacetime, counter-propagating OAM modes (±ℓ) experience ergosphere-like regions with enhanced coherence. We predict an OAM-dependent excess entanglement lifetime scaling as τexcess ∝ℓ2, arising from disformal couplings in the effective metric. Upon release from the BEC, these entangled polaritons convert to flying photons at c, preserving OAM and entanglement for direct integration into fiber or free-space quantum networks. This provides a novel, robust source of high-dimensional entanglement while offering an analog probe of geometric mechanisms potentially relevant to quantum gravity conjectures such as ER=EPR.
Atomic superfluids formed using Bose-Einstein condensates (BECs) in a ring trap are currently investigated in the context of superfluid hydrodynamics, quantum sensing, and matter-wave interferometry. The characterization of the rotational properties of such superfluids is important, but can presently only be performed by using optical absorption imaging, which completely destroys the condensate. Recent studies have proposed coupling the ring BEC to optical cavity modes carrying orbital angular momentum to make minimally destructive measurements of the condensate rotation. The sensitivity of these proposals, however, is bounded below by the standard quantum limit set by the combination of laser shot noise and radiation pressure noise. In this work we provide a theoretical framework that exploits the fact that the interaction between the scattered modes of the condensate and the light reduces to effective optomechanical equations of motion. We present a detailed theoretical analysis to demonstrate that the use of squeezed light and backaction evasion techniques allows the angular momentum of the condensate to be sensed with noise well below the standard quantum limit. Our proposal is relevant to atomtronics, quantum sensing, and quantum information.