Abstract: Reservoir computing is a brain inspired artificial intelligence algorithm with excellent performance on tasks such as speech recognition or time series prediction. We present this algorithm and its connection with neuroscience. The reservoir computing algorithm can be easily implemented in hardware. We present photonic implementations based on a simple architecture consisting of a single nonlinear node and a delay line. These analog implementations have performance comparable to digital implementations. We discuss the future of photonic reservoir computing and more generally of analog brain inspired computing.
Abstract: Long-distance quantum communication based on quantum repeater protocol is an important topic in quantum information science. To outperform the direct transmission of light in fiber, quantum memories with high-efficiency, high fidelity, high capacity and long storage time is crucial. Here we Achieve a high storage efficiency of 92% for a optical memory based on EIT scheme with cold atomic media of optical depth around 1000. To realize the true quantum memory, we have performed the storage of single photons generated by cavity-enhanced spontaneous parametric down conversion In the preliminary experiment, we have achieved a storage efficiency (SE) of 50%. Further improvements towards a high efficiency will be discussed.
CQT Colloquium by Gabriel Landi, University of São Paulo
Title: Measures of irreversibility using quantum phase space Date/Time: 28-Feb, 04:00PM Venue: CQT Level 3 Seminar Room, S15-03-15
Abstract: Irreversibility is an emergent concept, stemming from the complex interaction of a macroscopically large number of particles. It is also one of the most important concepts in thermodynamics, with ramifications in diverse fields. Understanding irreversibility from the microscopic level constitutes an active topic of research, particularly in the case of quantum system where irreversibility is known to emerge due to the entanglement between a system and its environment. In this lecture I will discuss recent results concerning the use of quantum phase space technique to establish measures of entropy production, the key quantifier of irreversibility. We will show how our formalism enables one to identify phase space currents operating both in the system and in the bath and which are ultimately responsible for the emergence of irreversibility. Our model also allows full control over the environment's degrees of freedom, which allows us to study also the interplay between irreversibility and the degree of non-Markovianity in a system. As we show, the system-environment mutual information is not a faithful witness of non-Markovianity, whereas the entropic distance of the environment from its initial state is. Finally, we will also discuss an application of these concepts to construct Onsager’s transport theory for the combined transfer of energy and squeezing in bosonic systems.
CQT Talk by Serge Massar, Université libre de Bruxelles (ULB)
CQT Talk by Man-Hong Yung Southern University of Science and Technology & Huawei Technologies
Title: Quantum Computing for the Near Future Date/Time: 22-Jan, 02:00PM Venue: CQT Level 3 Seminar Room, S15-03-15
Abstract: In the near future, it is possible that quantum devices with 50 or more high quality qubits can be engineered. On one hand, these quantum devices could potentially perform specific computational tasks that cannot be simulated efficiently by classical computers. On the other hand, the number of qubits would not be enough for implementing textbook quantum algorithms. An immediate question is how one might exploit these near term quantum devices for really useful tasks? In addition, one may also expect that these powerful quantum devices are accessible only through cloud services over the internet, which imposes the question of how might one verify the server, behind the internet, does own a quantum computer instead of a classical simulator? In this talk, I will share my thoughts over these questions based on my recent works.
Bio: Man-Hong Yung is an associate professor of physics at the Southern University of Science and Technology (SUSTech) located in Shenzhen, China, where he is also the vice dean of the Shenzhen Institute for Quantum Science and Engineering (SIQSE). Currently, he is on subbatical leave for joining Huawei Technologies as the Chief Scientist for quantum algorithms and software.
Dr. Yung obtained a bachelor and a master degree in physics at the Chinese University of Hong Kong. Then, he moved to the University of Illinois Urbana-Champaign where he obtained a PhD degree under the supervision of Prof. Anthony Leggett. Next, he joined Harvard University as a postdoctoral researcher in the research group of Prof. Alan Aspuru-Guzik. After that, he returned to China and worked as an assistant professor at the Institute for Interdisciplinary Information Sciences directed by Prof. Andrew Yao at Tsinghua University, before joining SUSTech. His recent research interests include quantum simulation, quantum control, quantum machine learning, and applications for near-term quantum devices. He is one of the inventors of the method of variational quantum eigensolver (VQE) for simulating quantum chemistry. He is also involved in the first experimental demonstration of applying the unitary coupled-cluster ansatz on VQE.
CQT PhD Thesis Defense by Jirawat Tangpanitanon
Title: Towards Quantum Simulation with Interacting Photons in Superconducting Circuits Date/Time: 29-Jan, 03:00PM Venue: CQT Level 3 Conference Room, S15-03-17
Abstract: Interacting photons in superconducting circuits have recently emerged as a promising platform for quantum simulation thanks to their local controllability and long coherence times. In this thesis, we first show how signatures of the celebrated many-body localization transition can be simulated using interacting photons in a nine site superconducting circuit.The measurements of the relevant energy eigenenergies and eigenstates were done by implementing a novel many-body spectroscopy method we develop in collaboration with Google Quantum Hardware Group benchmarked first by measuring the Hofstadter butterfly. In the second part of the thesis, we theoretically explore topological pumping with interacting photons for robust quantum state transfer in nonlinear photonic lattices. In the last part the existence of hidden long range order in driven-dissipative lattices as function of the interplay of different external driving with dissipation is studied. Possibilities of applying these results in different area of quantum technologies are discussed throughout the thesis.
CQT Talk by Miguel Navascues, IQOQI Vienna - Austrian Academy of Sciences
As quantum technologies develop, we acquire control of an ever-growing number of quantum systems. Unfortunately, current tools to certify non-classical properties of quantum states, such as entanglement and Bell nonlocality, are just practical for systems of a very modest size, of around 4 sites. Our approach to solve this "many-body quantum information problem" uses a class of linear transformations, called connectors, which join or chunk different sites of the considered network in a way that preserves the property under investigation. Applying these operations recursively, very quickly we end up with a network of manageable size, whose properties can be explored via usual techniques. In case of a successful detection, this method outputs a linear witness which admits an exact tensor network state representation. Using a normal desktop, we test our method by certifying entanglement, Bell nonlocality and supra-quantum Bell nonlocality in networks with hundreds of sites.