Distributed Quantum Computing Seminar Series
Join us for presentations and discussions across a broad range of topics related to Distributed Quantum Computing, while enjoying free pizza and drinks. DQCS takes place in Burchard 715 every Friday from 12-1:30PM.
3/9/2016 "Quantum Computing in the Century of Big Data" by Dr. Chao Wang, MeZocliq
Recent development of quantum computing has sparkled interest in the industry to utilize this mysterious and cutting-edge science to fundamentally solve one critical technology issue big corporations face today---data governance. After a decade of big data explosion, how to securely preserve the terabytes of data and how to effectively use the data are problems that need to be solved. Financial industry, which stores and consumes large amount of data, is especially eager to build a more secure and more robust infrastructure for the long-term advancement. This talk will explore the opportunities quantum computing can bring to big corporations, and analyze several fields that quantum mechanics may play a role in helping the industry grow.
Chao Wang joined a well-funded startup, meZocliq, in 2014 and has been working as a data modeler in the analytics team since then. MeZocliq is backed up by a major asset management firm, which grows quickly during the past few year. To help the clients with big data issue, meZocliq has developed a fully comprehensive clound-based enterprise solution suite, which offers end-to-end functionality across verticals and geographies for large corporations.
2/26/2016 "Silicon-chip-based Nonlinear Photonics" by Dr. Alex Gaeta, Columbia University
Not all that long ago, CMOS-compatible platforms based on Silicon were viewed as undesirable for integrated optics since lasers could not be created from such materials. However, over the past decade silicon has emerged as an exceptional material for manipulating light and has led to realization of ultrahigh-performance photonic devices in fields from data communications to medicine. I will discuss the realization of nonlinear photonics using silicon-based chips with only milliWatt power levels. Such capability enables numerous applications of nonlinear optics in telecommunications, sensing, spectroscopy, high-precision timing, quantum information, and optical computing.
Alex Gaeta received his Ph.D. in 1991 in Optics from the University of Rochester. From 1992 to 2015 he was on the faculty at the School of Applied and Engineering Physics at Cornell University. In July of 2015, he joined the faculty at the Department of Applied Physics and Applied Mathematics at Columbia University. He has published more than 200 papers in areas of integrated nonlinear optics, all-optical signal processing, nanophotonics, ultrafast nonlinear optics, and quantum effects in nonlinear optics. He co-founded PicoLuz, Inc. along with Michal Lipson and Alex Cable and is the founding Editor-in-Chief of Optica. He is a Fellow of the Optical Society of America and of the America Physical Society.
11/20/2015 "Getting Ready for Practical Quantum Computing: Lessons from Quantum Annealing with Dwave." by Dr. Siddhartha Santra, the Army Research Lab
The Dwave quantum annealing processor provides a physical realization of a non-universal form of adiabatic quantum computation that can still be useful for solving certain computationally-hard practical problems. Although, at current sizes, its advantages are not spectacular relative to classical algorithms it provides an interesting platform to test and study different aspects of quantum computation such as the role of entanglement, robustness of adiabatic computation and quantum error correction strategies. While the search for the class of useful problems that will provably be better suited for quantum annealing is still on - we can attempt to develop some intuition about the ingredients in the recipe for large-scale quantum computation in the future.
In this talk I will introduce quantum annealing (QA) as a finite temperature non-universal form of adiabatic quantum computation (AQC). After describing QA with Dwave I will describe two different problems - MAX-2-SAT and Associative memory recall - that we have implemented on the machine. Then I will discuss the relevant outstanding questions such as entanglement and the possibility of speed-up. Finally I will conclude with some lessons that we can draw at this stage about practical large-scale quantum computing.
11/13/2015 "Quantum control in ultracold atoms and molecules" by Prof. Svetlana Malinovskaya and Gengyuan Liu
Quantum control is a quantum mechanical methodology to transfer population from an initial state to a target state by using coherent light. In the past decades, the field of quantum control has grown rapidly both experimentally and theoretically. Among leading control techniques is the adiabatic passage, known for its robustness in the manipulation of dynamics in atoms and molecules, particularly, in control schemes at ultracold temperatures. The application of this technique is ranging from laser cooling and atom optics to quantum information processing and ultracold molecules.
In this talk, I will present our recent work on a new quantum control method for population inversion and preparation of non-equilibrium states in ultracold Rb atoms. The method suggests the implementation of a single nanosecond chipped pulse in the Raman scheme and serves as a viable substitute to a standard approach based on two separate pulses. I will also talk about how to prepare ultracold molecules using optical frequency combs.
10/30/2015 "Quantum Zeno Blockade: Toward Photonic Quantum Computing" by Professor Yuping Huang
Quantum-mechanical photons hold great promise for transformative information technology and beyond in years to come. It is the unifying goal of the Center for Distributed Quantum Computing to develop the world’s first photonic quantum computers that are scalable, portable, and affordable. To this end, there are fundamental and technical challenges that must be overcome on protocol, device, and system levels. In this talk, I will discuss with you a nascent quantum effect in nonlinear optics we discovered recently to overcome a major roadblock toward quantum computing using photons. I will show you the salient aspects of it and our experimental validations. I will also brief research activities undergoing or to take place in Laboratory for Quantum Enhanced Systems and Technology.
10/23/2015 "Non-resonant optical modulation of Laser and its potential in control, communication, and spectroscopy" by Professor Rainer Martini
Non-resonant optical modulation of Laser is a novel scheme in which the emission power as well as the emission frequency are changed based on optically generated carrier in the active medium – hence avoiding any specific design requirements for a laser structure while allowing direct access to the laser medium. Using thereby non-resonant excitation direct optical locking is avoided and alternative fast modulation possibility aside of electrical modulation achieved.
However, the difference in modulation characteristics allow for simultaneous electrical and optical modulation – whereby either amplitude of wavelength variation can be selectively compensated for – and thus allow independently control of output power and wavelength, something previously not achievable.
In addition such a setup could allow also for pure frequency modulation while suppressing the normally associated amplitude modulation, i.e. realizing AM without FM. Within this talk we present experimental results showcasing bandwidth and dynamical range for such non-resonant optical modulation for different semiconductor lasers and address the possibility of novel AM and FM modulation schemes, modulation spectroscopy and the possibility to establish an optical feedback loop.
10/16/2015 "Decoherence Control in Open Quantum Systesm via Internal Model of the Environment" by Prof. Narayan Ganesan
Quantum Information and Quantum Computation hold the key to faster information processing and reliable communication. Quantum information processing devices are also the promising alternative to digital information processing systems due to the reduction in feature size of silicon based technology. However, the problem of decoherence, which is caused by environmental interaction and which leads to collapse of quantum superposition, is currently the biggest roadblock towards exploitation of quantum speedup in computation. The problem has received much attention over the past several years and continues to be the subject of investigation, with techniques such fast action pulses, and quantum error correction. Although many of the techniques are effective for small group of qubits, problems such as scalability of error correction techniques and decoherence under arbitrary useful control pulses prevail.
In this presentation, we investigate decoherence control for quantum systems with the help of a scalable ancillary qubit. The ancillary system is entangled with the system of interest and the model of environmental interaction is used to counter the decohering interaction. Decoherence control utilizing the environmental interaction, which has not been studied before, is shown to be more robust and scalable with the help of the ancillary qubit. The example of decoherence elimination in single qubit, and 2-qubit system is presented in order to demonstrate the efficacy of the technique, which preserves the action of useful control while eliminating only the effects of decohering interaction. This technique also leads us to the idea of Internal Model Principle analogue for quantum control systems which is first of its kind.
10/09/2015 "Quantum Computing and Computational Finance" by Prof. Rupak Chatterjee
The complexities of the ﬁnancial world have grown dramatically in the twenty ﬁrst century. A clear manifestation of this was the 2008 subprime mortgage crisis that led to a global recession. The widespread application of simpliﬁed modeling techniques for the risk analysis of complex credit derivatives products, due to the lack of computational power and speed, was blamed for the lack of transparency of the real risks embedded in such assets. Quantum computers, may provide a completely new approach oﬀering massive data storage and an exponential speed up of computing power. The initial goal of this research eﬀort is to identify which computational ﬁnance problems are well suited for quantum computers. This consists of matching critical modeling issues such as improved credit rating methodologies and real time options risk management to appropriate computational ﬁnance techniques that are natural ﬁts for the current generation of quantum chips. Current quantum computers are based on quantum circuit models, adiabatic quantum computing, or topological quantum computing.
10/2/2015: "Qubit Decoherence Via Phase and Amplitude Noises" by Dr. Yushui Chen
Quantum dynamics of open systems is a generic paradigm that has been widely discussed in research fields ranging from atomic and optical physics to condensed matter physics and to quantum information science. It becomes clear that a deep understanding of the effects of environments on a quantum system such as the mechanisms of decoherence and entanglement in the framework of quantum open systems is both of fundamental interest in quantum foundation issues and of practical importance in quantum information and quantum computing. The mastery of quantum coherence and entanglement control is the key to the success of quantum design and engineering.
In this talk I will present highlights of our recent work on several key issues in quantum dynamics of quantum open systems including non-Markovian quantum dynamics, quantum trajectories and quantum control.
9/25/2015: "Controlling Exciton Photophysics in Single Walled Carbon Nanotubes" by Dr. Ibrahim Sarpkaya
Single-walled carbon nanotubes (SWCNTs) have recently gained tremendous interest as a nanomaterial for next generation optoelectronics and quantum photonic devices. However, the photophysics of excitons in SWCNTs is not yet fully understood and is largely affected by detrimental extrinsic effects, which give rise to strongly reduced device performance. Here, we demonstrate novel methods and to better understand and control the photophysics of excitons in SWCNTs. The first part of my talk presents novel ways to completely remove detrimental spectral diffusion and blinking in the emission of surfactant dispersed SWCNTs on millisecond time scales and also demonstrates pronounced single photon emission in combination with 50-fold enhanced emission efficiency. The demonstrated single photon emission is promising for practical applications in quantum cryptography. We also demonstrated a new regime of intrinsic exciton photophysics in ultra-clean SWCNTs with narrow emission linewidths, fourfold enhanced exciton dephasing times and prolonged emission lifetimes up to 18 ns. These lifetimes are two orders of magnitude better than prior measurements and in agreement with values predicted by theorists a decade ago. Furthermore, we present a novel method which controls exciton-acoustic phonon interaction at the nanoscale by utilizing laser vaporization growth of SWCNTs combined with copolymer wrapping.
9/18/2015: "Fiber based Polarization-entangled Photon Pairs for Quantum-key Distribution" by Dr. Yong Meng Sua
Entangled photon-pair sources at optical fiber’s low-loss propagation window are essential for global scale quantum-key distribution (QKD). Furthermore, direct generation of entangled photon-pairs in optical fiber can obviate the optical coupling issue and taking advantage of existing fiber-optics technologies. We demonstrated high purity polarization correlated and polarization entangled photon pair using only 10 m long dispersion flatten highly nonlinear fiber (HNLF). To address the practicality of long distance quantum communication, we investigated the effect of standard loss and multiple scattering on fiber based photon-pairs. Our findings indicate that both standard loss and multiple scattering in transmission channel are detrimental to quantum correlation polarization-correlated and polarization-entangled photon-pairs.
*This seminar series is co-sponsored by the Office of the Vice-Provost for Research and the Department of Physics and Engineering Physics.