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In this letter, an investigation of the use of a covariance matrix adaptation evolution strategy (CMA‐ES) algorithm is conducted as the phase‐locking method for multi‐channel coherent beam combining (CBC) for the first time. A comprehensive numerical analysis is carried out on the operational performances of the CMA‐ES based phase‐locking algorithm implemented into 7‐ and 19‐channel CBC systems in a filled‐aperture format. Through numerical simulations it can be verified that the CMA‐ES algorithm can readily lead to over 0.90 of normalised beam combining efficiency with appropriate algorithm parameter sets, which can also be optimised by a combinatorial study. The proposed CMA‐ES based phase‐locking algorithm is a feasible option for novel phase‐locking technique for a CBC system particularly when the local extremum issue becomes severe such as in CBC under turbulent atmospheric conditions.

In the next generation optical data storage systems, the lens-disk interface gap and the tolerance of the focus error will reduce dramatically, however, the rotation of the spindle motor could produce sinusoidal disturbances to the focus actuator system due to the skew of the disk and system mechanical vibrations, which consequently affect the focus precision and even cause the lens-disk collision. In order to avoid the lens-disk collision and increase the focus control precision, an optimal Q -parameterized controller is proposed in this paper. The parameter of the controller is solved based on some properly formulated linear matrix inequalities (LMIs). Simulation results show that the designed controller has an effective anti-collision capability with a good focus precision.

Due to its good conductive properties, unalloyed (pure) aluminum, such as EN AW-1050A H24, finds new fields of application in electromobility. To optimize components, the cyclic material behavior must be understood and described precisely as a foundation of a proper fatigue life estimation. Various cyclic tests were performed to not only derive the cyclic parameters to describe the material but also to find the most suitable procedure to deal with the challenges faced during the experiments. The main point of interest is the comparison between a surface-mounted clip-on extensometer and an optical system both used for strain control in cyclic tests. For the analysis of the anisotropic behavior of EN AW-1050A H24, un-notched flat specimens were extracted from sheet metal lengthways and crossways in respect to the rolling direction. While the cyclic material behavior for specimens of both directions of extraction is characterized by cyclic softening in general, the specimens extracted crossways show a strain-amplitude-dependent cyclic softening with strong strain localization especially at the contact points of the knives of the clip-on extensometer leading to an increased quantity of invalid experiments as well as sudden fractures. In the study, it was possible to show the benefits of a contactless optical strain control system when dealing with very soft metallic materials such as EN AW-1050A H24.

Compared with a traditional distributed control system (DCS), the use of the industrial optical bus control system (OCS) can lower automation investment costs, shorten project time, and reduce control system maintenance expenses. OCS industrial optical bus control system is composed of engineer station, operator station, redundant historical station, equipment management station, redundant control station, redundant industrial optical bus connection unit (RJU) and industrial optical bus intelligent data transmission unit (iDTU) and other equipment in which optical fiber is used for communication from iDTU to RJU and redundant control station. Use of optical fiber communication between the control station and the field data acquisition unit saves money compared to instrument cables.

In order to obtain highly accurate infrared spectra, the optical path scanning control system in a portable Fourier transform spectrometer (FTS) must be able to realize highly stable reciprocal scanning. To address the positional localization and speed fluctuation problems of optical path scanning control systems, an adaptive feedforward–nonlinear PI cascade composite control algorithm (AF-NLPI) is proposed. A physical model of an optical path scanning control system is established. Moreover, an adaptive feedforward compensator using a dynamic forgetting factor is proposed, and it was combined with a nonlinear PI cascade controller to form a composite controller. The control parameters were tuned using the atomic orbital search algorithm. Further, the simulation and experimental results demonstrate that the AF-NLPI can effectively improve the control accuracy and anti-interference ability of an optical path scanning control system in a portable FTS with high feasibility and practicality. By setting the scanning stroke of the system to 8 mm and scanning at 10 mm/s, the stability of the optical scanning speed reached 99.47% when controlled by the controller proposed in this paper, thus fulfilling the motion requirements for optical path scanning control systems.

The thermal environment is an important factor in the design of optical systems. This study investigated the thermal analysis technology of optical systems for navigation guidance and control in supersonic aircraft by developing empirical equations for the front temperature gradient and rear thermal diffusion distance, and for basic factors such as flying parameters and the structure of the optical system. Finite element analysis (FEA) was used to study the relationship between flying and front dome parameters and the system temperature field. Systematic deduction was then conducted based on the effects of the temperature field on the physical geometry and ray tracing performance of the front dome and rear optical lenses, by deriving the relational expressions between the system temperature field and the spot size and positioning precision of the rear optical lens. The optical systems used for navigation guidance and control in supersonic aircraft when the flight speed is in the range of 1–5 Ma were analysed using the derived equations. Using this new method it was possible to control the precision within 10% when considering the light spot received by the four-quadrant detector, and computation time was reduced compared with the traditional method of separately analysing the temperature field of the front dome and rear optical lens using FEA. Thus, the method can effectively increase the efficiency of parameter analysis and computation in an airborne optical system, facilitating the systematic, effective and integrated thermal analysis of airborne optical systems for navigation guidance and control.

Tests of quantum mechanics on a macroscopic scale require extreme control over mechanical motion and its decoherence 1 – 3 . Quantum control of mechanical motion has been achieved by engineering the radiation–pressure coupling between a micromechanical oscillator and the electromagnetic field in a resonator 4 – 7 . Furthermore, measurement-based feedback control relying on cavity-enhanced detection schemes has been used to cool micromechanical oscillators to their quantum ground states 8 . In contrast to mechanically tethered systems, optically levitated nanoparticles are particularly promising candidates for matter-wave experiments with massive objects 9 , 10 , since their trapping potential is fully controllable. Here we optically levitate a femtogram (10 −15  grams) dielectric particle in cryogenic free space, which suppresses thermal effects sufficiently to make the measurement backaction the dominant decoherence mechanism. With an efficient quantum measurement, we exert quantum control over the dynamics of the particle. We cool its centre-of-mass motion by measurement-based feedback to an average occupancy of 0.65 motional quanta, corresponding to a state purity of 0.43. The absence of an optical resonator and its bandwidth limitations holds promise to transfer the full quantum control available for electromagnetic fields to a mechanical system. Together with the fact that the optical trapping potential is highly controllable, our experimental platform offers a route to investigating quantum mechanics at macroscopic scales 11 . Quantum control of an optically levitated nanoparticle with a mass of just one femtogram is demonstrated in a cryogenic environment by feedback-cooling the motion of the particle to the quantum ground state.

Optical systems combining balanced loss and gain provide a unique platform to implement classical analogues of quantum systems described by non-Hermitian parity–time (PT)-symmetric Hamiltonians. Such systems can be used to create synthetic materials with properties that cannot be attained in materials having only loss or only gain. Here we report PT-symmetry breaking in coupled optical resonators. We observed non-reciprocity in the PT-symmetry-breaking phase due to strong field localization, which significantly enhances nonlinearity. In the linear regime, light transmission is reciprocal regardless of whether the symmetry is broken or unbroken. We show that in one direction there is a complete absence of resonance peaks whereas in the other direction the transmission is resonantly enhanced, a feature directly associated with the use of resonant structures. Our results could lead to a new generation of synthetic optical systems enabling on-chip manipulation and control of light propagation. It is now shown that coupled optical microcavities bear all the hallmarks of parity–time symmetry; that is, the system’s dynamics are unchanged by both time-reversal and mirror transformations. The resonant nature of microcavities results in unusual effects not seen in previous photonic analogues of parity–time-symmetric systems: for example, light travelling in one direction is resonantly enhanced but there are no resonance peaks going the other way.

Quantum communications technologies require a network of quantum processors connected with low-loss and low-noise communication channels capable of distributing entangled states. Superconducting microwave qubits operating in cryogenic environments have emerged as promising candidates for quantum processor nodes. However, scaling these systems is challenging because they require bulky microwave components with high thermal loads that can quickly overwhelm the cooling power of a dilution refrigerator. Telecommunication frequency optical signals, however, can be fabricated in significantly smaller form factors to avoid challenges caused by high signal loss, noise sensitivity and thermal loads due to their high carrier frequency and propagation in silica optical fibres. Transduction of information by means of coherent links between optical and microwave frequencies is therefore critical to leverage the advantages of optics for superconducting microwave qubits, while also enabling superconducting processors to be linked with low-loss optical interconnects. Here, we demonstrate coherent optical control of a superconducting qubit. We achieve this by developing a microwave–optical quantum transducer that operates with up to 1.18% conversion efficiency with low added microwave noise, and we demonstrate optically driven Rabi oscillations in a superconducting qubit. Superconducting qubits operate at microwave frequencies, but it is much more efficient to transmit information optically. Now, a superconducting qubit has been controlled with an optical signal by using a microwave–optical quantum transducer.

Periodically driven quantum many-body systems can display rich dynamics and host exotic phases that are absent in their undriven counterparts. However, in the presence of interactions such systems are expected to eventually heat up to a simple infinite-temperature state. One possible exception is a periodically driven many-body localized system, in which heating is precluded by strong disorder. Here, we use a gas of ultracold fermionic potassium atoms in optical lattices to prepare and probe such a driven system and show that it is indeed stable for high enough driving frequency. Moreover, we find a novel regime in which the system is exceedingly stable even at low drive frequencies, a particular feature of our driving scheme. Our experimental findings are well supported by numerical simulations and may provide avenues for engineering novel phases in periodically driven matter. Many-body localization, which exhibits a fascinating interplay between disorder and interactions, can be studied using ultracold atoms in a quasiperiodic chain. Adding periodic driving makes things even more interesting.