The Journal of Physics published a paper entitled as “Design of non-magnetic temperature control system for atomic vapor cell of atomic magnetometer”
Abstract. In order to make the atomic magnetometer work, the heater of the atomic vapor cell must ensure that the temperature can be accurately controlled and the magnetic noise should be reduced as much as possible. This work proposed a non-magnetic heater and designed a corresponding temperature control system. It shows that the heater structure has good heat preservation performance and so, control of the heating process is made easy. The test results indicate that the fluctuation range of vapor cell temperature is less than 0.018 ℃, 0.015 ℃ and 0.006 ℃ respectively at 40 ℃, 50 ℃ and 60 ℃. The effect of heater on the magnetic field cannot be observed by fluxgate magnetometer HS-MS-FG3LN-100 (<300pT).
از جمله نیازهای حیاتی در زمینه حسگرها و تجهیزات کوانتومی، مجتمع سازی و کاهش ابعاد فیزیکی پایین این ادوات است. حسگرهای کوانتومی کاربردهای مختلفی یافتهاند ور در تجهیزات پیشرفته آزمایشگاهی، دستگاههای الکترونیکی و سایر تجهیزات راهبردی به کار میروند.
در جهان، راهکارهای گوناگونی برای رسیدن به این هدف پیشنهاد شده و در حال توسعه است که یکی از این حوزه ها استفاده از ظرفیت نانوفوتونیک در طیف سنجی اتمی است.
به عنوان مثال استفاده از موجبرهای میکرونی برای هدایت نور و واکنش درونی با بخار اتمی از جمله مواردی بوده که با موفقیت روبه رو شده. همچنین از موارد با قابلیت بسیار زیاد میتوان به برهمکنش تک اتم با مدهای کاواک اشاره کرد.
یکی از موارد بسیار جذاب تسهیل کننده این ایده، استفاده از مدهای پلاسمونی به عنوان یک کاواک با قابلیت جفت شدگی آسان با گذارهای اتمی است. ایجاد جفت شدگی اتم با مد کاواک پلاسمونی نیاز به پیش شرایطی مانند شناخت کافی از انواع نانو ساختارهای پشتیبانی کننده از مدهای پلاسمونی و مشخصات مدهای پلاسمونی دارد، که باید به دقت به آن پرداخته شود.
باید توجه داشت که تاکنون کارهای زیادی به منظور به دام اندازی و سرمایش لیزری اتم ها با کمک امواج پلاسمون سطحی انجام شده و این موضوع نویدبخش نسل جدید حسگرهای کوانتومی خواهد بود که مشخصه اصلی حساسیت فوق العاده را به همراه ابعاد کوچک خواهد داشت.
پژوهش های موفقیت آمیز
همچنین تاکنون پتانسیل بالایی در ترکیب مدهای میرا در نانوساختارها با گذارهای اتمی وجود دارد، که این مورد به خوبی در آزمایشگاه مگنتوپلاسمونیک در دانشگاه شهید بهشتی و با حمایت ستاد فوتونیک و مواد پیشرفته معاونت علمی و فناوری ریاست جمهوری، مورد مطالعه قرار گرفته و نتیجه مطالعات برهمکنش موج میرا با بخار اتمی در مقالات معتبر به چاپ رسیده است. به عنوان مثال امکان سنجش فوق دقیق قطبش موج میرا ناشی از بازتاب کلی از سطح منشور، با کمک طیف سنجی اتمی با موفقیت نشان داده شد.
از مهمترین گامهای برداشته شده در آزمایشگاه مگنتوپلاسمونیک در حوزه اندرکنشهای کوانتومی اتم ها با امواج موجبری و فضای آزاد نور توانایی ساخت محفظه های با فشار پایین بخار اتمی روبیدیوم با ابعاد میلیمتری و میکرونی و همچنین محفظه های دوگانه با امکان جفت سازی کوانتومی اتم با مد موجبری پلاسمون سطحی یا میرا و یا سایر مدهای موجبری اشاره کرد.
همچنین ساخت و کار با گرمکن متناسب با طیف سنجی بخار اتمی به منظور داده برداری فلورسانسی و عبوری، دور زدن پهن شدگی داپلری با کمک میکرو سلول روبیدیوم، جفت شدگی اتم با موج میرا و طیف سنجی موج میرا و امکان بررسی اندرکنش واندوالس اتم با سطح و همچنین جفت سازی تراز گسسته کوانتومی با تراز پیوسته پلاسمون های سطحی و ایجاد تداخل فوق حساس فانو به منظور بهره گیری در حسگری کوانتومی از جمله حسگری میدان مغناطیسی در دیگر دستاوردها در این مسیر است
The Journal of Nature Physics published paper entitled as “Microwave electrometry with Rydberg atoms in a vapour cell using bright atomic resonances”
Atom-based standards for length and time as well as other physical quantities such as magnetic fields show clear advantages by enabling stable and uniform measurements. Here we demonstrate a new method for measuring microwave (MW) electric fields based on quantum interference in a rubidium atom. Using a bright resonance prepared within an electromagnetically induced transparency window we could achieve a sensitivity of ∼30 µV cm-1 Hz-1=2 and demonstrate detection of MW electric fields as small as ∼8 µV cm-1 with a modest set-up. The sensitivity is limited, at present, by the stability of our lasers and can be significantly improved in the future. Our method can serve as a new atom-based traceable standard for MW electrometry, with its reproducibility, accuracy and stability promising advances towards levels comparable with those attained in magnetometry at present.
In this days, the journal of Nature Communications published a new paper entitled as “Tracking Brownian motion in three dimensions and characterization of individual nanoparticles using a fiber-based high-finesse microcavity”
The dynamics of nanosystems in solution contain a wealth of information with relevance for diverse fields ranging from materials science to biology and biomedical applications. When nanosystems are marked with fluorophores or strong scatterers, it is possible to track their position and reveal internal motion with high spatial and temporal resolution. However, markers can be toxic, expensive, or change the object’s intrinsic properties. Here, we simultaneously measure dispersive frequency shifts of three transverse modes of a highfinesse microcavity to obtain the three-dimensional path of unlabeled SiO2 nanospheres with 300 μs temporal and down to 8 nm spatial resolution. This allows us to quantitatively determine properties such as the polarizability, hydrodynamic radius, and effective refractive index. The fiber-based cavity is integrated in a direct-laser-written microfluidic device that enables the precise control of the fluid with ultra-small sample volumes. Our approach enables quantitative nanomaterial characterization and the analysis of biomolecular motion at high bandwidth.
Plasmonic structures for phase-sensitive ellipsometry biosensing: a Review
Foozieh Sohrabi1, Sajede Saeidifard1 and Seyedeh Mehri Hamidi1*
Plasmonic biosensing endeavors to offer the ultrasensitivity below 10-7 RIU along with providing a label-free platform for the detection of biomarkers. Integrating the intensity (amplitude) sensing with phase property of light not only can increase the signal to noise ratio but also provides additional information of the phase changes compared to the conventional plasmonic technique. This information can be helpful for in-depth understanding of the biomolecular and cellular interactions of the sample. In this review, we aim to look into the recent works on plasmonic biosensing based on phase-sensitive ellipsometry technique and investigate the various structures that have been provided for this platform up to now. The structures based on thin films, colloids and disordered systems, nanoparticle/nanhole arrays, graphene and 3D structures have been reviewed. Undoubtedly, choosing a structural platform and optimizing its structural parameters can increase the biosensitivity as well as decreasing the limit of detection that plays a key role in biosensing. Due to the vast area of phase-sensitive plasmonics, we limit our focus to ellipsometry technique and its integration with plasmonics. We hope this review can open up new horizons towards the development and fabrication of highly sensitive plasmonic structures applicable in phase-sensitive biosensing.
In this days, the journal of optical material express published a new paper entitled as “Non-Hermitian metasurfaces for the best of plasmonics and dielectrics”
Abstract: Materials and their geometry make up the tools for designing nanophotonic devices. In the past, the real part of the refractive index of materials has remained the focus for designing novel devices. The absorption, or imaginary index, was tolerated as an undesirable effect. However, a clever distribution of imaginary index of materials offers an additional degree of freedom for designing nanophotonic devices. Non-Hermitian optics provides a unique opportunity to take advantage of absorption losses in materials to enable unconventional physical effects. Typically occurring near energy degeneracies called exceptional points, these effects include enhanced sensitivity, unidirectional invisibility, and non-trivial topology. In this work, we leverage plasmonic absorption losses (or imaginary index) as a design parameter for non-Hermitian, passive parity-time symmetric metasurfaces. We show that coupled plasmonic photonic resonator pairs, possessing a large asymmetry in absorptive losses but balanced radiative losses, exhibit an optical phase transition at an exceptional point and directional scattering. These systems enable new pathways for metasurface design using phase, symmetry, and topology as powerful tools.
In this days, the journal of sensors publishes a new paper entitled as “Pain and stress detection using wearable sensors and devices—A review“
Pain is a subjective feeling; it is a sensation that every human being must have experienced all their life. Yet, its mechanism and the way to immune to it is still a question to be answered. This review presents the mechanism and correlation of pain and stress, their assessment and detection approach with medical devices and wearable sensors. Various physiological signals (ie, heart activity, brain activity, muscle activity, electrodermal activity, respiratory, blood volume pulse, skin temperature) and behavioral signals are organized for wearables sensors detection. By reviewing the wearable sensors used in the healthcare domain, we hope to find a way for wearable healthcare-monitoring system to be applied on pain and stress detection. Since pain leads to multiple consequences or symptoms such as muscle tension and depression that are stress related, there is a chance to find a new approach for chronic pain detection using daily life sensors or devices. Then by integrating modern computing techniques, there is a chance to handle pain and stress management issue.
