Scientific Program

Conference Series Ltd invites all the participants across the globe to attend International Conference on Quantum Physics and Nuclear Engineering London, UK.

Day 1 :

OMICS International Quantum Physics 2016 International Conference Keynote Speaker Yukio Tomozawa photo
Biography:

Yukio Tomozawa obtained DSc in 1961 from Tokyo University. He was Assistant at Tokyo University (1956) and at Tokyo University of Education (1957-1959) - Member at the Institute for Advanced Study, Princeton, NJ (1964-1966). He was Assistant Professor, Associate Professor, Professor and Emeritus Professor at the University of Michigan, USA. He found that the Schwarzschild metric does not fit the data of time delay experiment in the field of general relativity. He has introduced a physical metric which fits the data. It was constructed with the constraint that the speed of light on the spherical direction is unchanged from that in vacuum. This modification changes the way we understand the nature of gravity drastically. In particular, the nature of compact objects, neutron stars and black holes, is very different from that described by the Schwarzschild metric. It also explains the dark energy, supernova explosion and high energy cosmic ray emission from AGN (Active Galactic Nuclei), massive black holes.

Abstract:

The author starts from the experimental test of General Relativity on time delay in the solar system by Shapiro et al. The most recent experiment using the Cassini satellite attained an 1 in 10^5 accuracy level. This indicates that the Schwarzschild metric is not a correct metric and the correct metric is the author’s physical metric, in which the speed of light on the spherical direction is constrained to be the value in vacuum. This is a conceptually natural assumption, since the spherical direction is perpendicular to the radial direction which is the direction of the gravity. In this new metric, the size of compact objects, neutron stars and black holes, becomes 2.60 times larger than that of the Schwarzschild radius and is called the extended horizon. The temperature of compact objects is found to be very high, as is evidenced from the existence of highly ionized atoms in the X-ray measurement of compact objects. In this metric, both the point source and a constant density distribution, the internal solution inside the extended horizon is shown to be a repulsive gravitational force, while the gravity outside the extended horizon remains attractive. The repulsive nature of gravity inside the extended horizon is the source for the supernova explosion as well as the reason for high energy cosmic rays generated from AGN, Active Galactic Nuclei, which are massive black holes.rn Using the physical metric in General Relativity, the author suggests that the masses of the merging black holes which produced the gravitational waves in LIGO, GW150914, must be reduced by a factor of 2.60. The masses of the merging black holes are 11.2 (+1.5, -1.5) M_{⊙} and 13.8 (+1.9, -1.5) M_{⊙} and the final mass of the resulting black hole is 23.8 (+1.5, -1.5) M_{⊙}. These masses of the merging black holes are consistent with the observed values of black hole masses.rn

Keynote Forum

Manijeh Razeghi

Northwestern University, USA

Keynote: Quantum science and technology: Application for daily life

Time : 10:00-10:30

OMICS International Quantum Physics 2016 International Conference Keynote Speaker Manijeh Razeghi  photo
Biography:

Manijeh Razeghi joined Northwestern University, Evanston, IL, as a Walter P Murphy Professor and Director of the Center for Quantum Devices in Fall 1991, where she created the undergraduate and graduate program in solid-state engineering. She is one of the leading scientists in the field of semiconductor science and technology, pioneering in the development and implementation of major modern epitaxial techniques. Her current research interest is in nanoscale optoelectronic quantum devices. She has authored or coauthored more than 1000 papers, more than 30 book chapters, and 16 books. She holds 55 US patents and has given more than 1000 invited and plenary talks. She received the IBM Europe Science and Technology Prize in 1987, the Achievement Award from the SWE in 1995, the RF Bunshah Award in 2004 and many best paper awards. She is an Elected Fellow of SWE (1995), SPIE (2000), IEC (2003), OSA (2004), APS (2004) IOP (2005), IEEE (2005) and MRS (2008). She received IBM Teacher of Excellence 2013 award. She is Editor, Associate, and Board Member of many journals, including Nano Science and Nano Technology.

Abstract:

When you look closely, Nature is nanotechnology and quantum sensing at its finest. From a single cell, a factory all by itself, to complex systems, such as the nervous system or the human eye, each is composed of specialized quantum-structures that exist to perform a specific function. This same beauty can be mirrored when we interact with the tiny physical world which is the realm of quantum mechanics. Electrons, photons, and even thermal properties can all be engineered at this level. Using Nature as a template, we have already applied nanotechnology to improve traditional sensors (e.g. artificial eyes, ears, and noses). However, beyond this is the more general “quantum sensing” area, which allows us to think creatively about interacting with and exploring physical processes on a truly fundamental level. Possibly the simplest aspect of Quantum Science and nanotechnology, the 2-D quantum well has dramatically enhanced the efficiency and versatility of electronic and optoelectronic devices. While this area alone is fascinating, nanotechnology has now progressed to 1-D (quantum wire) and 0-D (quantum dot) systems which exhibit remarkable and sometime unexpected behaviors. With these components serving as the modern engineer’s building blocks, it is a brave new world we live in, with endless possibilities for new technology and scientific discovery. There is still so much to learn and to be curious about. In this talk, I will present the latest Quantum Devices based on atomic and gap engineering of III-V semiconductor from deep us: 200 nm up to THZ; 300 microns.

Keynote Forum

Kazuhisa Kakurai

QuBS, JAEA & CEMS, RIKEN, Japan

Keynote: Quantum beam science: A bridge between nuclear science and nuclear application

Time : 10:30-11:00

OMICS International Quantum Physics 2016 International Conference Keynote Speaker Kazuhisa Kakurai photo
Biography:

Kazuhisa Kakurai has completed his PhD from TU Berlin working at the Hahn-Meitner Institut, Berlin. He joined the Institute for Solid State Physics of the University of Tokyo as an Assistant Professor and became a Professor in 1997. He was the Director General of the QuBS Directorate at the JAEA until 2014 and now serves as a General Adviser in the QuBS Center, JAEA in Tokai, Japan. Currently he is also Visiting Scientist at CEMS, RIKEN in Wako, Japan.

Abstract:

At the end of 19th century a series of revolutionary discoveries were made to lay the foundations of the today’s Quantum Beam Science. These are the discovery of x-ray by Roentgen in 1895, spontaneous radioactivity from uranium salt by Becquerel in 1896, followed by discoveries of radioactivity from polonium and radium by Curies in 1897. In years 1899 and 1900, Rutherford and Villard separated radiation into three types based on penetration of objects and deflection by a magnetic field and named them alpha, beta and gamma rays. Because alpha particles occur naturally, much of the early knowledge of atomic and nuclear physics, as exemplified by the Rutherford’s gold foil experiment leading to the discovery of atomic nucleus. But the particles and electrons emitted from radioactive nuclei have specific energies and low flux. Hence an generator was developed by Cockcroft and Walton to accelerate the protons performing the first artificial nuclear disintegration. Subsequently the discovery of neutrons by Chadwick and nuclear fission by Hahn, Meitner and Strassmann and the realization of nuclear chain reaction initiated nuclear energy research establishing the nuclear reactors, providing neutron sources with decent flux. The history shows how the discovery of these radiations goes hand in hand with the understanding of the atomic and nuclear phenomena and their applications. The most eminent application being the utilization of nuclear power for energy production leading to the establishment of atomic energy research institutes worldwide in the middle of 20th century. Though the nuclear power aspect was the primary aim of these institutes, nevertheless the utilization of concomitant radiations, i.e. quantum beams, in different field, such as medical, agricultural and condensed matter applications have been investigated intensively at the same time. In this talk I would like to exemplify the development of the quantum beam science in connection with nuclear science and application in the Quantum Beam Science Directorate activities at Japan Atomic Energy Agency.

Break: Networking & Refreshments Break 11:00-11:20 @ FOYER
  • Track 1: Quantum Science
Speaker

Chair

Manijeh Razeghi

Northwestern University, USA

Speaker

Co-Chair

Ian O Driscoll

Cork Institute of Technology and Tyndall National Institute, Ireland

Session Introduction

Yukio Tomozawa

University of Michigan, USA

Title: Evidence for a dark matter particle

Time : 11:20-11:45

Speaker
Biography:

Yukio Tomozawa obtained DSc in 1961 from Tokyo University. He was Assistant at Tokyo University (1956) and at Tokyo University of Education (1957-1959) - Member at the Institute for Advanced Study, Princeton, NJ (1964-1966). He was Assistant Professor, Associate Professor, Professor and Emeritus Professor at the University of Michigan, USA. He found that the Schwarzschild metric does not fit the data of time delay experiment in the field of general relativity. He has introduced a physical metric which fits the data. It was constructed with the constraint that the speed of light on the spherical direction is unchanged from that in vacuum. This modification changes the way we understand the nature of gravity drastically. In particular, the nature of compact objects, neutron stars and black holes, is very different from that described by the Schwarzschild metric. It also explains the dark energy, supernova explosion and high energy cosmic ray emission from AGN (Active Galactic Nuclei), massive black holes.

Abstract:

The author published a proposal in 1985 that suggested cosmic rays are emitted from AGN (Active Galactic Nuclei) or massive black holes. In that proposal, the knee energy in the cosmic ray energy spectrum is the interface between the radiation-dominated expansion rate and the matter-dominated expansion rate for an expanding heat bath. As such, it requires the existence of a particle of mass at 3 PeV, the knee energy value. Assuming that this provides a mass scale for new physics, one can compute the mass of the dark matter particle as the lowest mass state of the new physics. Choosing a supersymmetric theory which provides a large mass ratio, one can predict the dark matter particle mass of 8.1 TeV. The analysis of a recent HESS data shows a gamma ray spectrum that peaks at 7.6±0.1 TeV. The agreement between the theoretical prediction and the observational data suggests the search for the other predicted particles with the mass of 26.8 TeV, 78.0 TeV and 3 PeV.

Labonté Laurent

University of Nice Sophia Antipolis, France

Title: Silicon photonics: Generation of entangled photon pairs

Time : 11:45-12:10

Speaker
Biography:

Labonté Laurent studied in the University of Limoges (France) where he received a Master's degree in "Optical and High Frequency Telecommunication" (University of Limoges, France). He obtained the PhD degree in Physics in 2005 on both experimental and numerical study of microstructured fiber for non-linear optics and astronomy. From 2005 to 2006, he was an Assistant Professor. In 2006, he joined the group “Quantum Information with Light & Matter” of the Laboratory of Condensed Matter Physics (LPMC), as an Associate Professor of the University of Nice Sophia Antipolis. His research activities focus on generating, distributing and manipulating quantum information at telecom wavelength.

Abstract:

Integrated quantum photonics has already proven its suitability for high-performance photon-pair source realizations and basic quantum state simulation. Among all physical technological platforms (lithium niobate, KTP, III/V semiconductors), silicon photonics stands as a promising avenue for developing cost-effective quantum circuits, with the potential for on-chip signal processing. Thanks to the possibility of integrating electronics and photonics in a full monolithic fashion. Notably, integrated ring cavities already enable producing entangled photons, thanks to enhanced third-order nonlinear processes. In this talk, we report the generation of entangled photon pairs in micro-ring cavity based on silicon-on-insulator structure (SOI), in energy-time format, which is widely suited for the fiber based quantum key distribution (QKD) because of its robustness against polarization mode dispersion and disturbance. Furthermore, since this on-chip quantum entangled photons pair source is fully compatible with telecom components, it offers a path toward quantum photonic circuits for the next QKD real-world system.

Natalia Korolkova

University of St. Andrews, UK

Title: Gaussian quantum discord and the entangling power of a beamsplitter

Time : 12:10-12:35

Speaker
Biography:

Natalia Korolkova has completed her PhD in Theoretical Quantum Optics in 1996 from Moscow State University. During 1996-1997, she was a Post-doctoral Researcher at the Palacky University in Olomouc, Czech Republic, in Non-Classical Light and Quantum Cryptography. In 1997, she joined the University of Erlangen-Nuernberg, Germany, as a Humboldt Fellow working on quantum correlations of bright optical beams and fiber solitons. During 1999-2003, she led the Quantum Information group at the University of Erlangen. Since September 2003, she is Lecturer at the School of Physics and Astronomy, University of St. Andrews, UK. She has published over 70 research papers and book chapters.

Abstract:

A beamsplitter (BS) is frequently used to generate entangled continuous variable states, if at least one of the inputs is a quantum squeezed state. Interestingly, for mixed quantum states, a BS can create entanglement even from two input modes none of which exhibit any local squeezing, provided that they are correlated in a tailored way. These correlations are quantified by Gaussian quantum discord. We demonstrate that such discordant correlations and BS serve as a resource using three protocols: 1) Entanglement distribution by separable ancilla. Here, two modes A and B and the ancilla C are initially in a three-partite fully separable state. C interference on a BS first with A and then with B, consequently A and B become entangled. C remains separable throughout the protocol. The initial state ABC is separable but discordant, i.e., all three modes are correlated in a particular fashion. 2) Recovery of entanglement from the noise-affected squeezed states via interference with a correlated ``environmental’’ mode. 3) Generation of a three-partite entangled state by splitting on a BS a thermal state correlated with a vacuum mode. The created entanglement does not occur between the output modes of the BS but instead it emerges between one output mode and the remaining two modes taken together. This phenomenon is a key element for some of the above protocols, and for entanglement sharing. We will discuss in detail discordant states involved and unveil the seemingly counterintuitive emergence of entanglement in these protocols.

Speaker
Biography:

David Eimerl has an MA from Oxford University and obtained a PhD from Northwestern University in 1973. He became a program leader and chief scientist at the Lawrence Livermore National Laboratory in the Laser/ICF Program. In 2000, he founded EIMEX, providing contract services in lasers, optics, lasers in medicine, patent prosecution and custom high performance computer codes. He has published more than 140 papers in refereed journals and has several patents.

Abstract:

StarDriver is a class of laser fusion drivers that minimizes laser-plasma instabilities and improves laser-plasma coupling by the use of multi-beam laser architecture with both large system frequency bandwidth and dense, wide k-spectrum. It comprises 5000-25000 individual lasers (beamlets), each delivering nominally 100 joules in pulses of ~3-30 ns at a nominal wavelength of ~355 nm with better than 3-5 diffraction-limited performance. The beamlets are individually relatively narrowband (<1THz) to facilitate maximum laser performance, but the ensemble of beamlets span a wide frequency range. Currently available laser media enable ~ 2% at 355 nm with the possibility of system bandwidths approaching 10% in the future. Each beamlet has 2D SSD. StarDriver provides optimal asymptotic smoothing for hydrodynamic instabilities (0-1%), innovative focusing strategies including zooming, and the large bandwidth enables extremely rapid hydrodynamic smoothing times ~ 30 fs. The distribution of frequencies among the beamlets allows flexibility for fine control of the seeding of the Rayleigh-Taylor instability. The ultra-broad bandwidth combined with the large k-spectrum of the beamlets irradiating the plasma corona may enable complete suppression of the most problematic laser-plasma instabilities such as stimulated Brillouin backscatter, stimulated Raman scatter, cross-beam energy transfer, and the two plasmon decay instability. StarDriver offers potentially superior flexibility in laser drivers for ICF, enabling almost arbitrary sequencing of wavelength, polarization, focus, and fine control of the spatio-temporal properties of the drive in the corona. The highly modular strategy of StarDriver should enable an attractive development pathway as well as maximizing overall system efficiency.

Break: Networking & Lunch Break 13:00-13:45
Speaker
Biography:

Almut Beige completed her PhD in 1998 at the University of Goettingen in Germany. She is the Head of the Theoretcial Physics Group in the School of Physics and Astronomy at the University of Leeds, which she joined after working at Imperial College London and the Max-Planck Institute for Quantum Optics in Garching in Germany. She published 80 scientific papers, has an H-index of 23 and more than 2000 citations listed on ISI Web of Science. She currently serves on the Editorial Board of Journal of Modern Optics and European Physics Journal D.

Abstract:

Sonoluminescence is the intriguing phenomenon of energy concentration from an oscillating pres- sure field into a brief pulse of light via the actions of a bubble filled with atomic species. Since its discovery, there have been many theories on what mechanisms must be at work. The phenomenon attracted the interests of scientists from a wide range of disciplines, including physics, chemistry and engineering. In this paper, we develop a quantum optical model to analyse the dynamics of the atoms during the bubble collapse phase. Our model uses ideas of analogous work on cavity-mediated collective laser cooling of an atomic gas to very low temperatures and predicts many aspects of actual sonoluminescence experiments correctly. For example, we identify a mechanism responsible for the sudden emission of light during each bubble collapse phase. Moreover, our model might explain why certain atomic species in sonoluminescing bubbles become hotter than what one would expect from thermodynamic heating by rapid compression. In the long-term, our work might help to further increase the temperature of sonoluminescing bubbles for applications in sonochemistry, medicine, and the study of small volume plasmas.

Jianxin Chen

Chinese Academy of Sciences, China

Title: High performance InAs-based type-II superlattice infrared photo-detectors

Time : 14:10-14:35

Speaker
Biography:

Jianxin Chen has completed his PhD from the Graduate School, Chinese Academy of Sciences. He has been with Shanghai Institute of Metallurgy, Chinese Academy of Sciences; Swiss Federal Institute of Technology at Laussane; Bell Laboratories, Lucent Technologies; and Princeton University. He is now a Professor of Shanghai Institute of Technical Physics, Chinese Academy of Sciences. He has authored and co-authored more than 80 peer-reviewed journal papers. His current research interests are quantum structured materials for optoelectronic devices.

Abstract:

I will report our recent works on InAs-based superlattice photodiodes. The InAs/GaSb superlattice materials were conventionally grown on GaSb substrates and have been achieved excellent successes. However since the lattice constant of InAs is smaller than that of GaSb, GaSb-based superlattice structures are highly strained. The longer the cutoff wavelength, the bigger the strain is. This issue can be eliminated if the superlattice structures are grown on InAs substrates. Moreover, the growth temperature of the superlattice materials on InAs substrates can be significantly increased, which helps to improve the superlattice’s electrical properties, such as minority carrier lifetime, which is a bottleneck for superlattice photo-detector’s performances. InAs/GaSb superlattices on InAs substrates with sharp X-ray diffraction peaks have been obtained for the first time, indicating high crystalline quality of the material. Superlattice structures with different InAs thickness in each period was grown and examined. The results show that the lattice mismatch of the superlattices to the InAs substrates is not sensitive to the InAs thickness. Cutoff wavelength can be tuned from 6 μm to 12 μm by varying the InAs layer thickness from 14 MLs to 26 MLs. Optical responses and quantum efficiency are measured and changes linearly with the absorption thickness. P-I-N detectors based on the InAs-based superlattice materials also shown excellent electrical performances, which will be presented and discussed in detail in the talk.

Binayak S Choudhury

Indian Institute of Engineering Science and Technology, India

Title: Protocols for concentration of entanglement in multipartite quantum states

Time : 14:35-15:00

Speaker
Biography:

Binayak S Choudhury is Full Professor of the Department of Mathematics, Indian Institute of Engineering Science and Technology, Shibpur, India since 2003. He has supervised 13 PhD students and published more than 175 research articles in journals in several areas of Pure Mathematics, Applied Mathematics and Theoretical Physics. He has delivered lectures in many institutes and universities across the world. His works in Theoretical Physics are in Quantum Physics and Cosmology.

Abstract:

Quantum entanglement is considered as the most precious resource of Quantum Technology. Originally, the concept appeared in the famous EPR paper in 1935 in which entanglement between two parties was defined. It was only during the last decade of the twentieth century that the power of entanglement was discovered. In recent years, studies on entanglement attracted much attention due to its uses in the absolutely safe information transmission through Quantum Communication Protocols like Quantum Teleportation, Quantum Key Distribution, Quantum Secret Sharing, etc. Multipartite entanglement was considered and put to use at a later point of time. The quantification of entanglement had become necessary for which measures of entanglement have developed. In most of the cases, maximally entangled states are used, especially in Communication Protocols, although there are some reports of utilizing non-maximally entangled states as well. Thus, there is a need to increase the amount of entanglement, that is, to find the ways of creating more entanglement starting from a state which is initially less entangled. For this purpose Entanglement Concentration Protocols are proposed. Particularly, our discussion is on the protocols for entanglement concentration of multipartite quantum states, that is, quantum states which are shared by more than two parties.

Speaker
Biography:

Nir Bar-Gill is an Assistant Professor in the departments of Applied Physics and Physics at the Hebrew University in Jerusalem, Israel. He received his PhD in 2010 from the Weizmann Institute of Science in Israel, following which he spent 3 years as a Post-doctoral fellow at Harvard University, USA. His research focuses on NV centers in diamond, and in particular their relation to quantum information processing, quantum simulation and sensing. He has received several awards, including the Harvard Post-doctoral Award for career development and the Minerva ARCHES award.

Abstract:

Nitrogen-Vacancy (NV) color centers in diamond provide a unique nanoscale quantum spin system embedded in a solid-state structure. As such they are well suited for studies in a wide variety of fields, with emerging applications ranging from quantum information processing to magnetic field sensing and nano-MRI (Magnetic Resonance Imaging). Importantly, NVs possess unique optical transitions which allow for optical initialization and readout of their quantum spin state. In this talk I will introduce the field of NV centers, and describe our research into understanding and controlling these systems, with the goal of enabling fundamental research and future applications. I will present the techniques used for manipulation of the NV centers, and for enhancing their quantum coherence lifetime. Specifically, I will describe our recent work on extending the coherence time of arbitrary quantum states, and on spectrally characterizing the noise which limits coherence in shallow NVs. I will then demonstrate how these approaches can be used for magnetic field sensing and nanoscale NMR (Nuclear Magnetic Resonance) and MRI.

Manuel García-Méndez

CICFIM de la FCFM-UANL, Mexico

Title: Blue-green luminescence of Ce-doped ZnO thin films

Time : 15:25-15:50

Speaker
Biography:

Manuel García Méndez got his PhD at the CICESE-UNAM program in Ensenada, México in 2000. Then, he did a Post-doc staying at the Physics Department, University of Manchester in 2000-2001. From 2001 up to date, he has been a Titular Researcher at the CICFIM in Monterrey, NL México, in which he heads the Thin Film Laboratory.

Abstract:

Electronic, structural and photoluminescence properties of ZnO and Ce-doped ZnO thin films deposited on glass substrates by RF reactive-magnetron sputtering, and post annealed at 300C into an oxygen atmosphere, were investigated using X-ray diffraction (XRD), UV-Visible spectroscopy, XPS and PL measurements. Both films crystalized in wurzite structure with lattice parameters very similar in value to the stress-free standard. Transmittance of both films was high, of about 90% at the visible wavelength region (400-750 nm), with a band gap of Eg=3.23 eV and Eg=3.27 eV for pure and Ce-doped films respectively. The absorption edge of the doped film was shifted to the blue because of the Burstein-Moss effect. XPS spectra showed the coexistence of Ce3+ and Ce4+ ions in a proportion of about 70%:30% into the host ZnO lattice. Both type of ions induce extra electron states that allows multi-emission peaks at the blue-green region. Rearrangement of electronic levels because of added Ce into the ZnO matrix is discussed. Such films with blue-green luminescent properties are promising materials for potential applications in optoelectronic devices.

Break: Networking & Refreshments Break 15:50-16:10
  • Track 1: Quantum Science
    Track 2: In Depth Quantum Mechanics
Speaker

Chair

Yukio Tomozawa

University of Michigan, USA

Speaker

Co-Chair

Waseem Bakr

Princeton University, USA

Session Introduction

Norio Kawakami

Kyoto University, Japan

Title: Photo-induced topological phase transitions in ultracold fermions

Time : 16:10-16:35

Speaker
Biography:

Norio Kawakami has completed his PhD from Osaka University (Japan). His research concerns Theory of Condensed Matter Physics with particular emphasis on many-body problems where interactions between the constituent particles, such as electrons in solids, are very strong and thus give rise to novel quantum phenomena.

Abstract:

Photo-induced quantum phenomena have attracted much attention recently. Here, we address the following quantum phase transitions induced by external laser fields in cold fermions in optical lattices. Recently, concepts of topological phases of matter are extended to non-equilibrium systems, especially periodically driven systems. We construct a model which shows non-equilibrium topological phase transitions using a simple phenomenon in cold-atomic systems. We show that the celebrated Rabi oscillation has the possibility to tune the band structure in fermionic optical lattices and thereby drives non-equilibrium topological phase transitions. If time allows, we also address a possible realization of a photo-induced Kondo effect induced for cold fermions in optical lattices. Using a model for cold alkaline-earth atoms driven by optical coupling, we demonstrate that photo-induced Kondo effect overcomes the heating effect, and thus realizes orbital-spin entangled states leading to heavy-fermion liquids.

Ian O’Driscoll

Cork Institute of Technology and Tyndall National Institute, Ireland

Title: Ultrashort optical pulse generation in quantum dot lasers

Time : 16:35-17:00

Speaker
Biography:

Ian O’Driscoll obtained his PhD at UCC, Ireland in 2008, where he studied the carrier dynamics of InAs quantum dots. He then worked at Cardiff University, UK, as a Research Associate until 2012, where he investigated the physics of quantum dot laser materials and the consequences of carrier localization on device behavior. Since 2013, he works at the Tyndall National Institute, Ireland, where he is a recipient of the Starting Investigator Research Grant funded by Science Foundation Ireland. He has published over 30 papers in reputed journals and currently serves as Guest Editor for a special issue in MDPI Photonics.

Abstract:

This work uses semiconductor quantum dots, which are nanoscale inorganic materials, in order to achieve extremely short optical light pulses. Such pulses find use in high bit rate optical communications, wave division multiplexing, microscopy, multi-photon imaging and the generation of terahertz signal sources. Passively mode locked ultra-short pulses are created using an absorber section within a quantum dot lasing cavity, and the repetition rate, or time between successive pulses, is controlled by the length of the cavity. The work confirms the merits of random population for the generation of ultra-short pulses. When the quantum dots are randomly populated, they are independently occupied, which allows access to the entire gain spectrum. Sub pico-second pulse-widths were achieved using these methods, without any significant device engineering. A relatively simple method for significantly improving the optical pulse width when the dots are randomly populated will also be highlighted. These techniques can be applied to any quantum dot material.

Fabian Hartmann

Universität Würzburg, Germany

Title: Logical stochastic resonance with a coulomb-coupled quantum dot rectifier

Time : 17:00-17:25

Speaker
Biography:

Fabian Hartmann studied Physics at the University of Würzburg, Germany, and has completed his PhD from “Technische Physik” (Chair of Applied Physics), University of Würzburg. Currently, he is a post-doctoral research associate in the Nanoelectronics group at “Technische Physik”. His current research interests are noise assisted electron transport phenomena in low-dimensional semiconductor devices and resonant tunneling diode based sensors for infrared light detection applications. He has published more than 15 papers in reputed journals.

Abstract:

The exploitation of excess heat and noise has become a topical and significant branch of research, especially in electronics, where an ongoing trend towards sustainable, energy efficient and autonomous systems can be observed. Such a reuse is mainly possible by utilizing nonlinear systems and phenomena like e.g. stochastic resonance (SR) which enhances weak input signals by coupling to a noise floor. Furthermore, noise can improve the operation of logic gates: logical stochastic resonance (LSR) renders logic gates fault tolerant and reliable when the noise is situated in a suitable range. Both LSR and SR have in common the improvement of functional capabilities by application of noise to a system. Here, we present a Coulomb-coupled quantum dot (QD) device that is capable of generating a current through a QD by rectifying voltage fluctuations applied to the other QD. The magnitude and sign of the rectified current can be switched and controlled by external gates, and using these gates as logic inputs, enables the realization of various Boolean logic gate operations. Dependent on the noise amplitude and the control gate voltage, the device features AND, OR, NAND and NOR gate functionalities which can be switched between by either solely changing the noise magnitude or by a sole variation of the control gate voltage.

Waseem Bakr

Princeton University, USA

Title: Pair condensation in a spin-imbalanced two-dimensional Fermi gas

Time : 17:25-17:50

Speaker
Biography:

Waseem Bakr received his PhD from Harvard University in 2011. During his Doctoral thesis, he developed the technique of quantum gas microscopy for imaging atoms with single-site resolution in optical lattices. He used this technique to study quantum phase transitions in optical lattices in Hubbard models and in one-dimensional spin chains. Between 2011 and 2013, he was a Post-doctoral Researcher in Martin Zwierlein’s group at MIT, where he experimentally explored strongly-correlated fermions, including experiments on lower dimensional gases and spin-orbit coupled systems. Since 2013, he has been an Assistant Professor in the Department of Physics at Princeton University.

Abstract:

Strongly interacting Fermi gases of ultracold atoms are a clean and tunable platform for exploring high critical temperature superfluidity. This is particularly interesting because the physics of these gases has a close connection to superconductivity in strongly correlated materials. Early experiments in 3D gases have shed light on the crossover from BCS superfluidity to Bose-Einstein condensation of molecules and on the fate of superfluidity in spin-imbalanced gases. Here we study a strongly interacting spin-imbalanced Fermi gas in two-dimensions, where the low dimensionality enhances correlations and phase fluctuations in the gas. We observe pair condensation in the imbalanced gas and map out the critical polarization at which the condensate vanishes for different interaction strengths. At low temperatures, we observe phase separation between the superfluid and normal gas over a wide range of imbalance. The measurement of the phase diagram of strongly interacting fermions in two dimensions opens the door for a detailed investigation of exotic phases enhanced in two dimensions and in optical lattices like the elusive FFLO phase.