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Register a new userVacuum squeezed light for atomic memories at the D2 cesium line
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Authors
Sidney Burks
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We report the experimental generation of squeezed light at 852 nm, locked on the Cesium D2 line. 50% of noise reduction down to 50 kHz has been obtained with a doubly resonant optical parametric oscillator operating below threshold, using a periodically-polled KTP crystal. This light is directly utilizable with Cesium atomic ensembles for quantum networking applications
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Photonic molecules are composed of two or more optical resonators, arranged such that some of the modes of each resonator are coupled to those of the other. Such structures have been used for emulating the behaviour of two-level systems, lasing, and on-demand optical storage and retrieval. Coupled resonators have also been used for dispersion engineering of integrated devices, enhancing their performance for nonlinear optical applications. Delicate engineering of such integrated nonlinear structures is required for developing scalable sources of non-classical light to be deployed in quantum information processing systems. In this work, we demonstrate a photonic molecule composed of two coupled microring resonators on an integrated nanophotonic chip, designed to generate strongly squeezed light uncontaminated by noise from unwanted parasitic nonlinear processes. By tuning the photonic molecule to selectively couple and thus hybridize only the modes involved in the unwanted processes, suppression of parasitic parametric fluorescence is accomplished. This strategy enables the use of microring resonators for the efficient generation of degenerate squeezed light: without it, simple single-resonator structures cannot avoid contamination from nonlinear noise without significantly compromising pump power efficiency, and are thus limited to generating only weak degenerate squeezing. We use this device to generate 8(1) dB of broadband degenerate squeezed light on-chip, with 1.65(1) dB directly measured, which is the largest amount of squeezing yet reported from any nanophotonic source.
We consider the coherent stimulated Raman process developing in an optically dense and disordered atomic medium in application to the quantum memory scheme. Our theoretical model predicts that the hyperfine interaction in the excited state of alkali atoms can positively affect on the quantum memory efficiency. Based on the concept of the coherent information transfer we analyze and compare the memory requirements for storage of single photon and macroscopic multi-photon light pulses.
Squeezed states are a primary resource for continuous-variable (CV) quantum information processing. To implement CV protocols in a scalable and robust way, it is desirable to generate and manipulate squeezed states using an integrated photonics platform. In this Letter, we demonstrate the generation of quadrature-phase squeezed states in the radio-frequency carrier sideband using a small-footprint silicon-nitride microresonator with a dual-pumped four-wave-mixing process. We record a squeezed noise level of 1.34 dB ($pm$0.16 dB) below the photocurrent shot noise, which corresponds to 3.09 dB ($pm$0.49 dB) of quadrature squeezing on chip. We also show that it is critical to account for the nonlinear behavior of the pump fields to properly predict the squeezing that can be generated in this system. This technology represents a significant step toward creating and manipulating large-scale CV cluster states that can be used for quantum information applications including universal quantum computing.
For some crystalline materials, a regime can be found where continuous ductile cutting is feasible. Using precision diamond turning, such materials can be cut into complex optical components with high surface quality and form accuracy. In this work we use diamond-turning to machine a monolithic, square-shaped, doubly-resonant $LiNbO_3$ cavity with two flat and two convex facets. When additional mild polishing is implemented, the Q-factor of the resonator is found to be limited only by the material absorption loss. We show how our monolithic square resonator may be operated as an optical parametric oscillator that is evanescently coupled to free-space beams via birefringent prisms. The prism arrangement allows for independent and large tuning of the fundamental and second harmonic coupling rates. We measure $2.6pm0.5$ dB of vacuum squeezing at 1064 nm using our system. Potential improvements to obtain higher degrees of squeezing are discussed.
Vacuum ultraviolet (VUV) light at 118 nm has been shown to be a powerful tool to ionize molecules for various gas-phase chemical studies. A convenient table top source of 118 nm light can be produced by frequency tripling 355 nm light from a Nd:YAG laser in xenon gas. This process has a low efficiency, typically producing only nJ/pulse of VUV light. Simple models of the tripling process predict the power of 118 nm light produced should increase quadratically with increasing xenon pressure. However, experimental 118 nm production has been observed to reach a maximum and then decrease to zero with increasing xenon pressure. Here, we describe the basic theory and experimental setup for producing 118 nm light and a new proposed model for the mechanism limiting the production based on pressure broadened absorption.
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