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Lunes 7 de octubre
10:30 - 11:30 hr.
Quantum Research Center, Southwest Institute of Technical Physics (SWITP), Chengdu 610046, Sichuan, China
Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China (UESTC), Chengdu 611731, Sichuan, China
Efficient Studies on Optoelectronic Quantum Devices
Quantum information science has now attracted significant attention, since it has been well proved and is believed to support quantum computation, quantum communication and quantum metrology in the near future. The recent developments of optoelectronics do promote the progress in quantum information processing [1]. In this field, our united group in SWITP and UESTC recently made efforts in manufacturing quantum devices by using optoelectronic techniques.
Single photon emitters refer to light sources that release light in the form of individual particles or photons. They serve as the fundamental devices for quantum communication and are also well used in quantum detection and photonic quantum computation. We designed quantum dot embedded nanocavities to serve as efficient quantum emitters [2]; we fabricated heralded single-photon sources, emitting highly pure and speedy single photons, using spectral multiplexing technique [3]; and we succeeded in preparing defects in GaN usable as room temperature quantum random number generators [4].
Single photon detectors can respond to incident light signal as weak as one single photon. They play widespread roles in the field of quantum information processing by serving as key devices for, e.g., readout in quantum computing, receiving in quantum communication and photon measurement in quantum metrology. We focused our research on focal-plane single photon avalanche detectors (SPAD) and negative feedback avalanche diodes [5], optimized readout circuits for all types of SPADs, and recently developed SPAD arrays with more than 128 × 32 pixels for quantum imaging. Moreover, we have proposed fiber Bragg grating sensing system by utilizing single photon detectors [6].
Quantum entanglement is a phenomenon that arises when a collection of particles is created, interact, or exist in close proximity to each other in such a manner that the individual quantum states of each particle cannot be figured out independently from the states of the others, even if these particles are widely separated. As a fundamental resource, quantum entangled light sources are widely used in quantum information processing. Applying cascaded second-order nonlinear optical process in PPLN waveguides, we developed an entangled photon emitter with fidelity of 97% and noise level nearly 10 times better than ever reported [7]. Chip-integrated photon entangler with visibility of over 99% was established by fabricating Si3N4 micro-rings via micro/nano-processing [8]. We also applied the fabricated entanglement sources in quantum teleportation and quantum key distribution [9].
In addition, we explored Er-doped fiber based multiplexed quantum memory for simultaneously storing 1650 single photons [10], and studied optoelectromechanical devices for measuring minor quantities in quantum level [11].
Our studies might be a step forward to the realization of practical quantum information networks, and they may shed light on quantum information technology in the future.
References:
[1] D. E. Michaelis et al. Nature Photonics 4: 545–548 (2010).
[2] H. Z. Song et al. Optics Express, 2015, 23(12):16264-16272; H. Z. Song et al. Nanoscale Research Letters 12(1): 128 (2017); S. Huang et al., Current Optics and Photonics, 4(6):509-15 (2020).
[3] H. Yu et al., Photonics Research, 10(6):1417-1429 (2022); Y. R. Fan et al., Photonics Research, 9(6):1134-1143 (2021).
[4] Q. Luo et al., Optics Letters 45(15): 4224-4227 (2020).
[5] H. Z. Song, Chapter 9 in Advances Photodiodes - Research and Application. London: IntechOpen, 2018； H. Z. Song et al., IEEE Transactions on Electron Devices, 63(12):4845-51 (2016).
[6] Z. Ou et al., Optics Express 31(5): 8152-8159 (2023).
[7] Z. Zhang et al., npj Quantum Information 7(1): 123 (2021).
[8] Y. R. Fan et al., arXiv preprint 2209: 11417 (2022).
[9] S. Shen et al., Light: Science & Applications 12(1): 115 (2023); Y. R. Fan et al., Physical Review A. 108, L020601 (2023).
[10] S. H. Wei et al., npj Quantum Information, 2024, to be published.
[11] Q. Z. Cai et al., Physical Review A 108(2): 022419 (2023); B. L. Li et al., Optics Letters 48(10): 2571-2574 (2023).
Martes 8 de octubre
9:00 - 10:00 hr.
Dr. Mengke Cai
Quantum Research Center, Southwest Institute of Technical Physics (SWITP), Chengdu 610046, P. R. China
Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, P. R. China
Efficient Photocatalytic Energy Conversion
Understanding and manipulating intragap states in semiconductors may enable superior solar-to-fuel energy conversion [1,2]. The effect of intragap states on photocatalysis usually remains unclear and is sometimes contradictory. Quantum-confined colloidal quantum dots (QDs) provide a unique platform to tune the density and distribution of intragap states due to their discrete energy levels. Herein, intragap active domains, composed of Cu vacancies (VCu′) and high-valent Cu (Cu*) defect states, are constructed in copper-deficient Zn-doped CuInS2 QDs [3]. Note that these intragap states mainly exist at in-facet and on-edge defects in QDs, being away from the valence band maximum and close to Fermi level. Steady and transient optical spectra indicate that photoactivated Cu* states serving as photoinduced absorption centers can facilitate the generation of long-lived hot electrons (ca. 85 ps) as a manifestation of phonon bottleneck. Synergistically, the VCu′ states enable the holes capture and electron-hole pairs decoupling to suppress ultrafast Auger-like hot carrier cooling (ca. 178 fs). Moreover, the on-edge defects are demonstrated to play an active role in solar-to-fuel reduction kinetics through density functional calculation. As a result, the QDs exhibit an outstanding performance for fuel generation.
Keywords: colloidal quantum dots; defect engineering; hot-electron; intragap states; photocatalytic hydrogen generation
References:
[1] M. Cai et al., “Manipulating the Optically Active Defect–Defect Interaction of Colloidal Quantum Dots for Carbon Dioxide Photoreduction”, ACS Catal. 13, 15546-15557 (2023).
[2] M. Cai et al., “Decoration of BiVO4 Photoanodes with Near-Infrared Quantum Dots for Boosted Photoelectrochemical Water Oxidation”, ACS Appl. Mater. Interfaces 13, 50046-50056 (2021).
[3] M. Cai et al., “Regulating intragap states in colloidal quantum dots for universal photocatalytic hydrogen evolution”, Appl. Catal., B 343, 123572 (2024).
Martes 8 de octubre
11:30 - 12:30 hr.
División de Ciencias e Ingenierías, Departamento de Física, Universidad de Guanajuato, México
Entropías no-aditivas que dependen solo de la probabilidad. Algunas de sus consecuencias. Mecánica cuántica y relatividad general modificadas
Entropías no aditivas, que dependen de uno o varios parámetros, han sido propuestas en la literatura desde hace tiempo. En 2010, propuse una clase de entropías no aditivas que no dependen de ningún parámetro, sino únicamente de la probabilidad. Mostraré que estas entropías tienen profundas implicaciones en la física a energías cercanas a la de Planck, modificando tanto la mecánica cuántica como la relatividad general.
Para sistemas con muy pocos microestados, estas entropías podrían ser relevantes; mientras que, para muchos microestados, coinciden con la entropía usual de Boltzmann-Gibbs. Esto no ocurre con las entropías no aditivas tradicionales que dependen de parámetros.
Miércoles 9 de octubre
9:00 - 10:00 hr.
Dr. Juan Azorín Nieto
División de Ciencias Básicas e Ingeniería, Departamento de Física, Universidad Autónoma Metropolitana, México
La Dosimetría Termoluminiscente Aplicada en Física Médica
El término radiación ionizante es muy amplio, abarca tanto radiación electromagnética como corpuscular, con la energía suficiente para alterar el estado físico de la materia en la que incide haciendo que los átomos queden ionizados. En determinadas circunstancias, la presencia de estos iones en los tejidos vivos puede alterar los procesos biológicos normales; por lo que la radiación ionizante puede constituir un riesgo para la salud humana si no se emplea en una forma apropiada y segura.
Por tal motivo, la medición de la energía depositada por la radiación ionizante en la materia, disciplina conocida como dosimetría de la radiación ionizante, es una necesidad fundamental en las aplicaciones de las radiaciones ionizantes y muy especialmente en el campo de la física médica. Este tipo de mediciones pueden efectuarse de manera muy eficiente aplicando el fenómeno conocido como termoluminiscencia.
En esta plática se describe brevemente el fenómeno de termoluminiscencia y los modelos que tratan de explicarlo; así como su aplicación a la dosimetría de la radiación ionizante en física médica.
Jueves 10 de octubre
9:00 - 10:00 hr.
Departamento de Física , CINVESTAV, México
Recubrimientos Luminiscentes y sus Aplicaciones en Iluminación y Recolección de Luz Solar
El desarrollo de materiales Luminiscentes enfocados a su uso en dispositivos emisores de luz blanca (WLED´s) y recolección de luz solar ha derivado en estrategias que contemplan la integración de nuevos materiales y dispositivos que además permitan una aproximación sustentable desde el punto de vista ecológico. En esta aproximación es crucial la síntesis de fósforos y recubrimientos que mejoren la eficiencia energética de dispositivos emisores de luz y fotovoltaicos mediante la conversión espectral. El manejo apropiado de conversión de rangos espectrales puede incidir en la eficacia de dispositivos ya desarrollados con tecnologías de bajo costo. En esta platica se revisará la utilización de compuestos híbridos (orgánicos-inorgánicos) así como solo-inorgánicos con los que se pretende optimizar la eficacia de dispositivos de iluminación de estado sólido y fotovoltaicos mediante un diseño apropiado de conversión espectral. También se comentará sobre nuevos dispositivos que incidan en este mismo propósito usando las características de nuevos materiales emergentes.
Jueves 10 de octubre
11:30 - 12:30 hr.
Departamento de Física , Universidad de Maryland, USA
Detection of Gravitational Waves and the Dawn of Gravitational-Wave Astrophysics
Fifty years ago, the dream of directly detecting gravitational waves was at a crucial transition. Despite early claims by Joe Weber, resonant bar detectors had failed to confirm the General Relativity prediction that gravitational waves should be traveling through space and passing through the Earth. The waves were evidently too weak, if they existed at all. However, Rainer Weiss and a few others had begun to explore the possibility of using laser interferometers to detect the tiny ripples in spacetime that are gravitational waves. Decades of development finally led to the construction and operation of the LIGO detectors in the United States and to a few similar detectors in other parts of the world, and in 2015, the LIGO detectors succeeded in observing a clear event from a pair of black holes which spiraled inward and merged. Many more discoveries have followed, including a dramatic multi-messenger event from the first detected merger of a pair of neutron stars. I will summarize the main discoveries and the current state of the field of detecting gravitational waves and using them to test physics theories and astrophysics models.
Viernes 11 de octubre
9:00 - 10:00 hr.
Chair, Department of Physics, University of California, Merced, USA
Controlling Chaos and Transport in Biological Active Fluids
In recent years a new direction in bio-inspired fluids has emerged: transport in active fluids. This field brings together concepts from soft matter, such as liquid crystal physics, with ideas from fluid dynamics. In such systems, the motion and flows of the fluid may be dominated by self-propulsion of the fluid components. For biological systems, this self-propulsion can result from the action of molecular motors, or be driven by the autonomous motion of cells. In this talk I will review some of the recent and interesting concepts in this field – including some recent work on active fluid dynamics in a microtubule/kinesin motor-based fluid from my own lab – with the aim of inspiring new directions in the physics of biological cells.
Viernes 11 de octubre
10:30 - 11:30 hr.
Dr. Ian Cavin
NHS Tayside Medical Physics, Ninewells Hospital, Dundee, United Kingdom
The Hospital Medical Physicist: What every Physicist needs to know
The role of Physicists in Medicine is extremely varied and rewarding. As part of a multi- disciplinary team supporting and advising patients, carers, clinicians, medical Physicists are well respected for their scientific and problem-solving skills. From advice for individual patients, to the training and education of staff, analysis of clinical scans, to the design, development and testing of equipment for clinical and research services are examples of the types of activities undertaken.
A thorough understanding of the physical principles as well ability to communicate complex scientific concepts to a non-scientific audience clearly and concisely is crucial for patient, staff and service safety.
Rapid advances in the development of equipment used for diagnosis and treatment require medical physicists to keep their skills and knowledge up-to-date. Dr. Ian Cavin outlines what every physicist needs to know when considering a career as a clinical scientist in medicine. He discusses the challenges and rewards he has faced during his 15 years working as a Hospital Medical Physicist.
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