July 27, 2026
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, China Physics 19, 89
“A ring of optical fiber can be made to host phenomena that originated in the realm of high-energy physics.
Yang and colleagues traced the spectral evolution of an optical pulse injected into the ring. When they did so, they observed Zitterbewegung: the oscillation of the center of mass of a wave packet along the frequency axis caused by the noncommutativity of the scalar and vector potentials. This trembling motion (a direct translation of the original German) is the photonic analogue of the relativistic jittering predicted for Dirac electrons. It persists without requiring spectral detuning, spatial gradients, or time-dependent external driving. But when modulation detuning is introduced, an Abelian electric field is activated and Bloch oscillations—the bouncing back and forth of particles in a periodic lattice—appear. The coexistence of non-Abelian and Abelian electric fields causes the Zitterbewegung and the Bloch oscillations to interfere (Fig. 1).
Yang and his colleagues’ experiment opens several promising avenues for future exploration and practical applications. Their fiber-ring-based three-control architecture is directly compatible with thin films of lithium niobate, a transparent, nonlinear crystal with myriad photonic applications [7]. Programmable non-Abelian circuits could be fashioned on chip-scale platforms to harness the interference between Zitterbewegung and Bloch oscillations. For example, the interference could enable reconfigurable frequency-domain signal processing by jointly steering the polarization texture and the spectral distribution of multiplexed frequency combs. What’s more, because the frequency-dimension system naturally interfaces with fiber networks, these functionalities could be integrated, loss-free, into existing telecommunication infrastructure.”