Storage and retrieval of optical information in levitated cavityless optomechanics

We theoretically consider light storage in a single nanoparticle levitated in an optical dipole trap and subjected to nonlinear feedback cooling. The storage protocol is realized by controlling the coupling between mechanical displacement and signal pulse by maneuvering the intensity of writing and readout pulses. The process involves writing and readout pulses at one mechanical frequency below the signal pulse. We demonstrate that during the writing pulse, a signal pulse is stored as a mechanical excitation of the nanoparticle oscillation. It is then shown that a readout pulse at later time can retrieve the stored optical information from the mechanical oscillator. A long storage lifetime of 2 ms is obtained in our system due to the absence of clamping losses. Further, we describe that our protocol can be used for wavelength conversion and shows a saturation in the conversion efficiency as a function of cooperativities of the writing and readout pulses. We also illustrate that the presence of linear feedback heating can lead to the amplification of the retrieved photon energy. Our prototype for light storage with levitated optomechanics can be used to explore the possibility of quantum memories for photonic states.