@article{14802,
abstract = {Frequency-stable lasers form the back bone of precision measurements in science and technology. Such lasers typically attain their stability through frequency locking to reference cavities. State-of-the-art locking performances to date had been achieved using frequency modulation based methods, complemented with active drift cancellation systems. We demonstrate an all passive, modulation-free laser-cavity locking technique (squash locking) that utilizes changes in spatial beam ellipticity for error signal generation, and a coherent polarization post-selection for noise resilience. By comparing two identically built proof-of-principle systems, we show a frequency locking instability of 5×10−7 relative to the cavity linewidth at 10 s averaging. The results surpass the demonstrated performances of methods engineered over the last five decades, potentially enabling an advancement in the precision control of lasers, while creating avenues for bridging the performance gaps between industrial grade lasers with scientific ones due to the afforded simplicity and scalability.},
author = {Diorico, Fritz R and Zhutov, Artem and Hosten, Onur},
issn = {2334-2536},
journal = {Optica},
keywords = {Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials},
number = {1},
pages = {26--31},
publisher = {Optica Publishing Group},
title = {{Laser-cavity locking utilizing beam ellipticity: accessing the 10−7 instability scale relative to cavity linewidth}},
doi = {10.1364/optica.507451},
volume = {11},
year = {2024},
}
@article{18226,
abstract = {Spontaneous parametric downconversion (SPDC) in quantum optics is an invaluable resource for the realization of high-dimensional qudits with spatial modes of light. One of the main open challenges is how to directly generate a desirable qudit state in the SPDC process. This problem can be addressed through advanced computational learning methods; however, due to difficulties in modeling the SPDC process by a fully differentiable algorithm, progress has been limited. Here, we overcome these limitations and introduce a physically constrained and differentiable model, validated against experimental results for shaped pump beams and structured crystals, capable of learning the relevant interaction parameters in the process. We avoid any restrictions induced by the stochastic nature of our physical model and integrate the dynamic equations governing the evolution under the SPDC Hamiltonian. We solve the inverse problem of designing a nonlinear quantum optical system that achieves the desired quantum state of downconverted photon pairs. The desired states are defined using either the second-order correlations between different spatial modes or by specifying the required density matrix. By learning nonlinear photonic crystal structures as well as different pump shapes, we successfully show how to generate maximally entangled states. Furthermore, we simulate all-optical coherent control over the generated quantum state by actively changing the profile of the pump beam. Our work can be useful for applications such as novel designs of high-dimensional quantum key distribution and quantum information processing protocols. In addition, our method can be readily applied for controlling other degrees of freedom of light in the SPDC process, such as spectral and temporal properties, and may even be used in condensed-matter systems having a similar interaction Hamiltonian.},
author = {Rozenberg, Eyal and Karnieli, Aviv and Yesharim, Ofir and Foley-Comer, Joshua and Trajtenberg-Mills, Sivan and Freedman, Daniel and Bronstein, Alexander and Arie, Ady},
issn = {2334-2536},
journal = {Optica},
number = {6},
pages = {602--615},
publisher = {Optica Publishing Group},
title = {{Inverse design of spontaneous parametric downconversion for generation of high-dimensional qudits}},
doi = {10.1364/optica.451115},
volume = {9},
year = {2022},
}
@article{22,
abstract = {Conventional ultra-high sensitivity detectors in the millimeter-wave range are usually cooled as their own thermal noise at room temperature would mask the weak received radiation. The need for cryogenic systems increases the cost and complexity of the instruments, hindering the development of, among others, airborne and space applications. In this work, the nonlinear parametric upconversion of millimeter-wave radiation to the optical domain inside high-quality (Q) lithium niobate whispering-gallery mode (WGM) resonators is proposed for ultra-low noise detection. We experimentally demonstrate coherent upconversion of millimeter-wave signals to a 1550 nm telecom carrier, with a photon conversion efficiency surpassing the state-of-the-art by 2 orders of magnitude. Moreover, a theoretical model shows that the thermal equilibrium of counterpropagating WGMs is broken by overcoupling the millimeter-wave WGM, effectively cooling the upconverted mode and allowing ultra-low noise detection. By theoretically estimating the sensitivity of a correlation radiometer based on the presented scheme, it is found that room-temperature radiometers with better sensitivity than state-of-the-art high-electron-mobility transistor (HEMT)-based radiometers can be designed. This detection paradigm can be used to develop room-temperature instrumentation for radio astronomy, earth observation, planetary missions, and imaging systems.},
author = {Botello, Gabriel and Sedlmeir, Florian and Rueda Sanchez, Alfredo R and Abdalmalak, Kerlos and Brown, Elliott and Leuchs, Gerd and Preu, Sascha and Segovia Vargas, Daniel and Strekalov, Dmitry and Munoz, Luis and Schwefel, Harald},
issn = {2334-2536},
journal = {Optica},
number = {10},
pages = {1210--1219},
publisher = {Optica Publishing Group},
title = {{Sensitivity limits of millimeter-wave photonic radiometers based on efficient electro-optic upconverters}},
doi = {10.1364/OPTICA.5.001210},
volume = {5},
year = {2018},
}