Improving quantum annealing by engineering the coupling to the environment
Mojdeh S. Najafabadi,
Daniel Schumayer,
Chee-Kong Lee,
Dieter Jaksch,
David A. W. Hutchinson
EPJ Quantum Technology
10
44
(2023)
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A large class of optimisation problems can be mapped to the Ising model where all details are encoded in the coupling of spins. The task of the original mathematical optimisation is then equivalent to finding the ground state of the corresponding spin system which can be achieved via quantum annealing relying on the adiabatic theorem. Some of the inherent disadvantages of this procedure can be alleviated or resolved using a stochastic approach, and by coupling to the external environment. We show that careful engineering of the system-bath coupling at an individual spin level can further improve annealing.
Quantum-enhanced interferometer using Kerr squeezing
Nikolay Kalinin,
Thomas Dirmeier,
Arseny A. Sorokin,
Elena A. Anashkina,
Luis Sanchez-Soto,
Joel F. Corney,
Gerd Leuchs,
Alexey V. Andrianov
NANOPHOTONICS
12
(14)
2945-2952
(2023)
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One of the prime applications of squeezed light is enhancing the sensitivity of an interferometer below the quantum shot-noise limit, but so far, no such experimental demonstration was reported when using the optical Kerr effect. In prior setups involving Kerr-squeezed light, the role of the interferometer was merely to characterize the noise pattern. The lack of such a demonstration was largely due to the cumbersome tilting of the squeezed ellipse in phase space. Here, we present the first experimental observation of phase-sensitivity enhancement in an interferometer using Kerr squeezing.
Superresolution Enhancement in Biphoton Spatial-Mode Demultiplexing
Imaging systems measuring intensity in the far field succumb to Rayleigh's curse, a resolution limitation dictated by the finite aperture of the optical system. Many proof-of-principle and some two-dimensional imaging experiments have shown that, by using spatial mode demultiplexing (SPADE), the field information collected is maximal, and, thus, the resolution increases beyond the Rayleigh criterion. Hitherto, the SPADE approaches are based on resolving the lateral splitting of a Gaussian wave function. Here, we consider the case in which the light field originates from a biphoton source, i.e., spontaneous parametric down-conversion, and a horizontal separation is introduced in one of the two photons. We show that a separation induced in the signal photon arm can be superresolved using coincidence measurements after projecting both photons on Hermite-Gauss modes. Remarkably, the Fisher information associated with the measurement is enhanced compared to the ordinary SPADE techniques by root K, where K is the Schmidt number of the two-photon state that quantifies the amount of spatial entanglement between the two photons.
Superresolution Enhancement in Biphoton Spatial-Mode Demultiplexing
Imaging systems measuring intensity in the far field succumb to Rayleigh’s curse, a resolution limitation dictated by the finite aperture of the optical system. Many proof-of-principle and some two-dimensional imaging experiments have shown that, by using spatial mode demultiplexing (SPADE), the field information collected is maximal, and, thus, the resolution increases beyond the Rayleigh criterion. Hitherto, the SPADE approaches are based on resolving the lateral splitting of a Gaussian wave function. Here, we consider the case in which the light field originates from a biphoton source, i.e., spontaneous parametric down-conversion, and a horizontal separation is introduced in one of the two photons. We show that a separation induced in the signal photon arm can be superresolved using coincidence measurements after projecting both photons on Hermite-Gauss modes. Remarkably, the Fisher information associated with the measurement is enhanced compared to the ordinary SPADE techniques by K, where K is the Schmidt number of the two-photon state that quantifies the amount of spatial entanglement between the two photons.
All-in-One Photoactivated Inhibition of Butyrylcholinesterase Combined with Luminescence as an Activation and Localization Indicator: Carbon Quantum Dots@Phosphonate Hybrids
Gulia Bikbaeva,
Anna Pilip,
Anastasia Egorova,
Ilya Kolesnikov,
Dmitrii Pankin,
Kirill Laptinskiy,
Alexey Vervald,
Tatiana Dolenko,
Gerd Leuchs, et al.
Photopharmacology is a booming research area requiring a new generation of agents possessing simultaneous functions of photoswitching and pharmacophore. It is important that any practical implementation of photopharmacology ideally requires spatial control of the medicinal treatment zone. Thus, advances in the study of substances meeting all the listed requirements will lead to breakthrough research in the coming years. In this study, CQDs@phosphonate nanohybrids are presented for the first time and combine biocompatible and nontoxic luminescent carbon quantum dots (CQDs) with photoactive phosphonate enabling inhibition of butyrylcholinesterase (BChE), which is a prognostic marker of numerous diseases. The conjunction of these components in hybrids maintains photoswitching and provides enhancement of BChE inhibition. After laser irradiation with a wavelength of 266 nm, CQDs@phosphonate hybrids demonstrate a drastic increase of butyrylcholinesterase inhibition from 38% up to almost 100% and a simultaneous luminescence decrease. All the listed hybrid properties are demonstrated not only for in vitro experiments but also for complex biological samples, i.e., chicken breast. Thus, the most important achievement is the demonstration of hybrids characterized by a remarkable combination of all-in-one properties important for photopharmacology: (i) bioactivity toward butyrylcholinesterase inhibition, (ii) strong change of inhibition degree as a result of laser irradiation, luminescence as an indicator of (iii) bioactivity state, and of (iv) spatial localization on the surface of a sample.
Sensing Rotations with Multiplane Light Conversion
M. Eriksson,
A. Z. Goldberg,
M. Hiekkamaki,
F. Bouchard,
J. Rehacek,
Z. Hradil,
Gerd Leuchs,
R. Fickler,
Luis Sanchez-Soto
We report an experiment estimating the three parameters of a general rotation. The scheme uses quantum states attaining the ultimate precision dictated by the quantum Cramer-Rao bound. We realize the states experimentally using the orbital angular momentum of light and implement the rotations with a multiplane light-conversion setup, which allows one to perform arbitrary unitary transformations on a finite set of spatial modes. The observed performance suggests a range of potential applications in the next generation of rotation sensors.
Günter Ellrott,
Paul Beck,
Vitaliy Sultanov,
Sergej Rothau,
Norbert Lindlein,
Maria Chekhova,
Vojislav Kristic
Advanced Photonics Research
4
(10)
2300159
(2023)
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Circular dichroism is a unique chiroptical signature of the chirality of a system and is a prevalent way to characterize and distinguish systems on a fundamental level and for their technological applicability. Thus, engineering and maximizing the chiroptical response of a single chiral object or a metasurface composed of chiral entities is a formidable task. Current efforts strongly focus on individual metallic nanostructures and their periodic ensembles to harvest on (resonant) plasmonic properties and interactions. This route, however, waives the advantages of high-refractive-index nanoscale materials embracing low dissipative losses at optical wavelengths and electromagnetic fields penetrating and propagating in such materials. Herein, a strong circular dichroism is demonstrated in square lattices of nanohelices made of the high-refractive-index semiconductor germanium, with dissymmetry factors outperforming metal-based ensembles. The observation of a much higher dissymmetry emerges for illumination with spatially coherent light, in comparison to spatially incoherent light. High dissymmetry is attributed to cooperative coupling between single helices, resulting from the combination of dielectric resonances of both the individual helical building blocks and the highly ordered lattice.
Quasiclassical approach to the nonlinear Kerr dynamics
Mojdeh S. Najafabadi,
Andrei B. Klimov,
Luis Sanchez-Soto,
Gerd Leuchs
Optics Communications
545
129717
(2023)
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We examine the quasiclassical approximation to the self-Kerr nonlinear effect. The corresponding dynamics appears as classical trajectories, with the quantumness of the state included via its Wigner function. We obtain analytical estimates of the optimal squeezing attainable that compare fairly well with the numerical quantum solution. We delimit the range of parameters for which the quasiclassical solution retains relevant quantum features.<br><br>
Fiber-Optical Sources of Quantum Squeezed Light
A. V. Andrianov,
Nikolay Kalinin,
A. A. Sorokin,
E. A. Anashkina,
Gerd Leuchs
Optoelectronics Instrumentation and Data Processing
59
(1)
28-38
(2023)
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Quantum squeezed states of light characterized by a reduced quantum uncertainty with respect to one of the quadrature variables smaller than the uncertainty of the vacuum state (the standard quantum limit) play an important role in the current fundamental and applied research. The main information concerning the proprieties and manifestations of the squeezed states are presented. A concise review of the methods for obtaining and detecting the quantum squeezed light is performed; at that, a special attention is payed to fiber-optical schemas. The Kerr mechanism of squeezed state generation that is realized in various variants of fiber-optic systems is considered in detail. An experimental scheme of generation of polarization-squeezed states based on a nonlinear polarization-maintaining fiber is presented. Different factors that limit squeezing are considered.
Protecting Quantum Modes in Optical Fibers
Muhammad Abdullah Butt,
Paul Roth,
Gordon Wong,
Michael Frosz,
Luis Sanchez-Soto,
E. A. Anashkina,
A. V. Andrianov,
Peter Banzer,
Philip Russell, et al.
Physical Review Applied
19
054080
(2023)
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Polarization-preserving fibers maintain the two polarization states of an orthogonal basis. Quantum communication, however, requires sending at least two nonorthogonal states and these cannot both be preserved. We present an alternative scheme that allows for using polarization encoding in a fiber not only in the discrete, but also in the continuous-variable regime. For the example of a helically twisted photonic crystal fiber, we experimentally demonstrate that using appropriate nonorthogonal modes, the polarization-preserving fiber does not fully scramble these modes over the full Poincaré sphere, but that the output polarization will stay on a great circle; that is, within a one-dimensional protected subspace, which can be parametrized by a single variable. This allows for more efficient measurements of quantum excitations in nonorthogonal modes.
Influence of Initial Surface Roughness on LIPSS Formation and Its Consecutive Impact on Cell/Bacteria Attachment for TiAl6V4 Surfaces
Lamborghini Sotelo,
Tommaso Fontanot,
Sanjana Vig,
Patrick Herre,
Peyman Yousefi,
Maria Helena Fernandes,
George Sarau,
Gerd Leuchs,
Silke Christiansen
Advanced Materials Technologies
8
(12)
(2023)
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The influence of the initial surface roughness of TiAl6V4 samples on the orientation and periodicity of the resulting laser-induced periodic surface structures (LIPSS), as well as the surface wettability and chemistry is reported here. Before LIPSS fabrication, initial sample surface roughness is adjusted by variations of finial polishing steps with polishing grain sizes of 18.3, 8.4, 5, and 0.5 mu m. A 3 x 3 irradiation matrix was defined and lasered on all samples by changing the laser power and distance between consecutive laser scans. The resulting structures were characterized by scanning electron microscopy (SEM), atomic force microscopy, Raman spectroscopy, and contact angle measurements. As a further step, three representative generated structures were chosen to explore their bone implant viability by resazurin assays, alkaline phosphatase activity, and direct SEM imaging of the induced cells (MG63) and bacteria (Escherichia coli and Staphylococcus aureus). Results show that initial surface roughness has big influence on the wettability of the resulting surface, as well as inducing small variations on the orientation of the generated LIPSS. Structures generated with a higher integrated fluence have also shown to enhance cell differentiation while reducing bacterial activity, making them a great candidate for improved bone implant compatibility and durability.
3D Nanocomposite with High Aspect Ratio Based on Polyaniline Decorated with Silver NPs: Synthesis and Application as Electrochemical Glucose Sensor
Anna A. Vasileva,
Daria V. Mamonova,
Vladimir Mikhailovskii,
Yuri V. Petrov,
Yana G. Toropova,
Ilya E. Kolesnikov,
Gerd Leuchs,
Alina A. Manshina
In this paper, we present a new methodology for creating 3D ordered porous nanocomposites based on anodic aluminum oxide template with polyaniline (PANI) and silver NPs. The approach includes in situ synthesis of polyaniline on templates of anodic aluminum oxide nanomembranes and laser-induced deposition (LID) of Ag NPs directly on the pore walls. The proposed method allows for the formation of structures with a high aspect ratio of the pores, topological ordering and uniformity of properties throughout the sample, and a high specific surface area. For the developed structures, we demonstrated their effectiveness as non-enzymatic electrochemical sensors on glucose in a concentration range crucial for medical applications. The obtained systems possess high potential for miniaturization and were applied to glucose detection in real objects-laboratory rat blood plasma.
Near single-photon imaging in the shortwave infrared using homodyne detection
O. Wolley,
S. Mekhail,
P. -A Moreau,
T. Gregory,
G. Gibson,
Gerd Leuchs,
M. J. Padgett
Proceedings of the National Academy of Sciences of the United States of America
120
(10)
e216678120
(2023)
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Low-light imaging is challenging in regimes where low-noise detectors are not yet available. One such regime is the shortwave infrared where even the best multipixel detector arrays typically have a noise floor in excess of 100 photons per pixel per frame. We present a homodyne imaging system capable of recovering both intensity and phase images of an object from a single frame despite an illumination intensity of ??? 1 photon per pixel. We interfere this weak signal which is below the noise floor of the detector with a reference beam that is ??? 300, 000 times brighter, record the resulting interference pattern in the spatial domain on a detector array, and use Fourier techniques to extract the intensity and phase images. We believe our approach could vastly extend the range of applications for low-light imaging by accessing domains where low-noise cameras are not currently available and for which low-intensity illumination is required.
Local sampling of the SU(1,1) Wigner function
Nicolas Fabre,
Andrei B. Klimov,
Gerd Leuchs,
Luis Sanchez-Soto
AVS Quantum Science
5
014404
(2023)
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Despite its indisputable merits, the Wigner phase-space formulation has not been widely explored for systems with SU(1,1) symmetry, as a simple operational definition of the Wigner function has proved elusive in this case. We capitalize on unique properties of the parity operator, to derive in a consistent way a bona fide SU(1,1) Wigner function that faithfully parallels the structure of its continuous-variable counterpart. We propose an optical scheme, involving a squeezer and photon-number-resolving detectors, that allows for direct point-by-point sampling of that Wigner function. This provides an adequate framework to represent SU(1,1) states satisfactorily.
Physical Mechanisms Underpinning the Vacuum Permittivity
The debate about the emptiness of space goes back to the prehistory of science and is epitomized by the Aristotelian 'horror vacui', which can be seen as the precursor of the ether, whose modern version is the dynamical quantum vacuum. In this paper, we suggest to change a common view to 'gaudium vacui' and discuss how the vacuum fluctuations fix the value of the permittivity, e(0), and permeability, mu(0), by modelling their dynamical response by three-dimensional harmonic oscillators.
Observation of Robust Polarization Squeezing via the Kerr Nonlinearity in an Optical Fiber
Nikolay Kalinin,
Thomas Dirmeier,
Arseny A. Sorokin,
Elena A. Anashkina,
Luis Sanchez-Soto,
Joel F. Corney,
Gerd Leuchs,
Alexey V. Andrianov
Advanced quantum technologies
6
2200143
(2023)
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Squeezed light is one of the resources of photonic quantum technology. Among the various nonlinear interactions capable of generating squeezing, the optical Kerr effect is particularly easy-to-use. A popular venue is to generate polarization squeezing, which is a special self-referencing variant of two-mode squeezing. To date, polarization squeezing generation setups have been very sensitive to fluctuations of external factors and have required careful tuning. In this work, a development of a new all-fiber setup for polarization squeezing generation is reported. The setup consists of passive elements only and is simple, robust, and stable. More than 5 dB of directly measured squeezing is obtained over long periods of time without any need for adjustments. Thus, the new scheme provides a robust and easy-to-set-up way of obtaining squeezed light applicable to different applications. The impact of pulse duration and pulse power on the degree of squeezing is investigated.
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