Stroboscopic high-order nonlinearity for quantum optomechanics

Abstract

High-order quantum nonlinearity is an important prerequisite for the advanced quantum technology leading to universal quantum processing with large information capacity of continuous variables. Levitated optomechanics, a field where motion of dielectric particles is driven by precisely controlled tweezer beams, is capable of attaining the required nonlinearity via engineered potential landscapes of mechanical motion. Importantly, to achieve nonlinear quantum effects, the evolution caused by the free motion of mechanics and thermal decoherence have to be suppressed. For this purpose, we devise a method of stroboscopic application of a highly nonlinear potential to a mechanical oscillator that leads to the motional quantum non-Gaussian states exhibiting nonclassical negative Wigner function and squeezing of a nonlinear combination of mechanical quadratures. We test the method numerically by analyzing highly instable cubic potential with relevant experimental parameters of the levitated optomechanics, prove its feasibility within reach, and propose an experimental test. The method paves a road for experiments instantaneously transforming a ground state of mechanical oscillators to applicable nonclassical states by nonlinear optical force.

Fast Quantum Interference of a Nanoparticle via Optical Potential Control

“…It is well known that dynamics in non-harmonic potentials allow for quantum state preparation beyond the Gaussian realm [11][12][13][14][15]. One may be skeptical, however, if the nonlinear features of diffraction-limited optical potentials can be exploited to generate non-Gaussian quantum states given that nanoparticle wavepackets are notoriously small (compared to the optical wavelength) and subject to decoherence from light scattering.…”

“…At the heart of the protocol is the preparation of a non-Gaussian state in step 2. The pulsed dynamics in a cubic potential V 2 (x) ∝ x 3 imprints a cubic phase on the particle wavefunction ψ(x) → ψ(x) exp[−(i/ )V 2 (x)t] (see [14] for alternative ideas to prepare non-Gaussian states using a cubic potential). In analogy to diffraction at a phase grating [30][31][32], the cubic phase results in fringes in momentum space, clearly reflecting its non-Gaussianity (Fig.…”