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Yoon Jungbae,Kim Kihwan,Na Yisoo,Lee Donghun 한국물리학회 2023 Current Applied Physics Vol.50 No.-
Pulse-level protocols are commonly used in quantum information and sensing experiments. However, finite pulse width, inevitable in many cases due to experimental conditions, can affect the overall performance of the quantum measurement. Here, we study the effect of finite pulse width on quantum sensing experiments based on the solid-state spin qubits: nitrogen-vacancy centers in diamond. We perform magnetic sensing experiments of DC and AC fields using canonical sensing protocols: Ramsey interferometry, Hahn echo, and XY8 dynamical decoupling. By varying the width of π/2 and π pulse used in the protocols, we estimate the amount of phase accumulation during the pulses and correct their effects by compensating the qubit evolution time for time offsets due to the phase accumulation. In this way, we are able to recover optimal conditions for maximum sensitivity.
Yoon, Junghyo,Yoon, Hee-Sook,Shin, Yoojin,Kim, Sanghyun,Ju, Youngjun,Kim, Jungbae,Chung, Seok 1637.934400 2017 Nanomedicine: Nanotechnology, Biology and Medicine Vol.13 No.5
<P><B>Abstract</B></P> <P>Electrospun and ethanol-dispersed polystyrene-poly(styrene-co-maleic anhydride) (PS-PSMA) nanofibers (NFs) were used as a platform for the selective capture and three-dimensional culture of EpCAM-positive cells in cell culture medium and whole blood. The NFs were treated with streptavidin to facilitate bond formation between the amino groups of streptavidin and the maleic anhydride groups of the NFs. A biotinylated anti-EpCAM monoclonal antibody (mAb) was attached to the streptavidin-conjugated NFs via the selective binding of streptavidin and biotin. Upon simple mixing and shaking with EpCAM-positive cancer cells in a wide concentration range from 10 to 1000,000 cells per 10mL, the mAb-attached NFs (mAb-NFs) captured the Ep-CAM positive cells in an efficiency of 59%-67% depending on initial cell concentrations, with minor mechanical capture of 14%-36%. Captured cells were directly cultured, forming cell aggregates, in the NF matrix, which ensures the cell proliferation and follow-up analysis. Furthermore, the capture capacity of mAb-NFs was assessed in the presence of whole blood and blood lysates, indicating cluster formation that captured target cells. It is anticipated that the antibody-attached NFs can be employed for the capture and analysis of very rare EpCAM positive circulating cancer cells.</P> <P><B>Graphical Abstract</B></P> <P>Polystyrene-poly(styrene-co-maleic anhydride) (PS-PSMA) electrospun nanofibers (NFs) conjugated by anti-EpCAM monoclonal antibody is presented as an integrative platform for target cell capture and culture. The developed NFs has inter-fiber space for efficient selective cell capturing in wide concentration range of cell containing suspensions. Captured cells could be directly cultured in the NFs matrix, to ensure a cell culture environment.</P> <P>[DISPLAY OMISSION]</P>
Field averaging effect and estimation of minimum sample size in wide-field diamond microscopy
Yoon Jungbae,Jeong Jugyeong,Lee Donghun 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.10
Wide-feld diamond microscopy is a powerful imaging method based on diamond nitrogen-vacancy (NV) centers. It enables magnetic imaging over wide areas of sample with fast data acquisition. However, there can exist feld averaging efect resulting from the large feld gradient around magnetic samples and the collective measurement with ensemble NV centers in a difraction-limited laser spot. As a result, the overall magnitude of magnetic felds is greatly reduced compared to the actual felds. Here, we conduct micromagnetic simulation on diferent sizes of magnetic samples with various spatial resolutions. We fnd that based on the magnetic sensitivity and the spatial resolution of a wide-feld diamond microscope, one can estimate the minimum size of sample resolvable with the setup. This provides useful information in the design of an experiment without unnecessary trial and error measurements.
Development of a low-energy beam transport system at KBSI heavy-ion accelerator
Bahng, Jungbae,Lee, Byoung-Seob,Sato, Yoichi,Ok, Jung-Woo,Park, Jin Yong,Yoon, Jang-Hee,Choi, Seyong,Won, Mi-Sook,Kim, Eun-San Elsevier 2015 Nuclear Instruments & Methods in Physics Research. Vol.769 No.-
<P><B>Abstract</B></P> <P>The Korea Basic Science Institute has developed a heavy ion accelerator for fast neutron radiography [1]. To meet the requirements for fast neutron generation, we have developed an accelerator system that consists of an electron cyclotron resonance ion source (ECR-IS), low-energy beam transport (LEBT) system, radio-frequency quadrupole (RFQ), medium-energy beam transport system, and drift tube linac. In this paper, we present the development of the LEBT system as a part of the heavy ion accelerator system, which operates from the ECR-IS to the RFQ entrance.</P>
Magnetic imaging of a single ferromagnetic nanowire using diamond atomic sensors
Lee, Myeongwon,Jang, Bumjin,Yoon, Jungbae,Mathpal, Mohan C,Lee, Yuhan,Kim, Chulki,Pane, Salvador,Nelson, Bradley J,Lee, Donghun IOP 2018 Nanotechnology Vol.29 No.40
<P>Recent advances in nanorobotic manipulation of ferromagnetic nanowires bring new avenues for applications in the biomedical area, such as targeted drug delivery, diagnostics or localized surgery. However, probing a single nanowire and monitoring its dynamics remains a challenge since it demands high precision sensing, high-resolution imaging, and stable operations in fluidic environments. Here, we report on a novel method of imaging and sensing magnetic fields from a single ferromagnetic nanowire with an atomic-scale sensor in diamond, i.e. diamond nitrogen-vacancy (NV) defect center. The distribution of static magnetic fields around a single Co nanowire is mapped out by spatially distributed NV centers and the obtained image is further compared with numerical simulation for quantitative analysis. DC field measurements such as continuous-wave ODMR and Ramsey sequence are used in the paper and sub Gauss level of field sensing is demonstrated. By imaging magnetic fields at a single nanowire level, this work represents an important step toward tracking and probing of ferromagnetic nanowires in biomedical applications.</P>