At the occasion of the 60 anniversary of the department, we give a brief introduction of the recent progress on quantum information research over the last few years, including quantum search algorithm, nuclear magnetic resonnace quantum computing experiment, quantum communication theory and experiment. In quantum algorithm study, we put forward the concept of phase matching in quantum searching, corrected a mistake at that time, and furthermore we constructed a quantum search algorithm with 100% successful rate which improves the Grover algorithm. In NMR quantum computing, we have demonstrated several quantum algorithms using 2 to 7 qubits NMR systems. In quantum communication, we have proposed the idea of distributed quantum communication and applied the idea to quantum key distribution, quantum secret sharing and quantum secure direct communication. We have constructed dozens of quantum communication protocols based on this idea. We have demonstrated quantum communication over a 2m distance in free space in laboratory.
At the occasion of the 60 anniversary of the department, we give a brief introduction of the recent progress on quantum information research over the last few years, including quantum search algorithm, nuclear magnetic resonnace quantum computing experiment, quantum communication theory and experiment. In quantum algorithm study, we put forward the concept of phase matching in quantum searching, corrected a mistake at that time, and furthermore we constructed a quantum search algorithm with 100% successful rate which improves the Grover algorithm. In NMR quantum computing, we have demonstrated several quantum algorithms using 2 to 7 qubits NMR systems. In quantum communication, we have proposed the idea of distributed quantum communication and applied the idea to quantum key distribution, quantum secret sharing and quantum secure direct communication. We have constructed dozens of quantum communication protocols based on this idea. We have demonstrated quantum communication over a 2m distance in free space in laboratory.
Quantum Information Science is a cross-disciplinary subject that has arisen in the last twenty years. It concerns itself with the consequences of our most complete description of the physical world (that is, quantum mechanics) for the reliable, secure, private, and rapid processing of information, both in communication and computation. While its invention is often ascribed to the famous theoretical physicist Richard Feynman in the 1980s, his contributions were only one of many that initiated the field around that time. While he perceived that new types of physical devices, in which the quantum laws of superposition and entanglement function at the logical level, could give new power in the simulation of quantum physics, it was others (Bennett, Brassard) who showed that the uncertainty principle led to fundamentally more secure ways of communicating secret messages. It was yet others (Deutsch, Vazirani) who understood that quantum theory defined a new kind of Turing machine, and that not only quantum physics simulations, but potentially many other computational problems, are sped up in this machine. And it was yet another (Shor) who found a simple, very fast algorithm for prime factorization. The word "qubit" was coined only in 1995. Its introduction is indicative of a new mindset that has developed in recent years for studying and using quantum systems. "Qubit" now stands for a durable paradigm that spans a very wide variety of fields. It thus has many sub-meanings: first, it is the basic abstract unit of information for workers ranging from optical communication engineers to NMR spectroscopists to black-hole theorists. Second, it is the name we now routinely give to physical two level systems, as they are realized by photons, atomic and ionic eigenlevels, electronic and nuclear spin, structural defects in solids, and circulating-current states of superconducting devices. Physics has long dealt with some of these two-level systems, but calling them qubits implies a whole suite of interrelated ideas and capabilities that we ascribe to these systems: the ability to precisely set, and to precisely measure, the quantum state of one unique specimen, to avoid its coupling with the environment while at the same time strongly and controllably coupling the qubits together, to exploit the resulting quantum entanglement as a resource for metrological, cryptographic, and computational tasks. Quantum Information is a very diverse subject pursued today in many different directions, by many hundreds of researchers internationally: In theoretical physics, it has enlivened and sharpened the understanding of efficient representations of entangled many-particle wavefunctions, and has provided the prospect of applications for new concepts such as anyons and majorana fermions. Information theorists has benefitted from having a rigorous extension of the basis of their field, in which classical information theory is subsumed into a greatly broader subject. Theoretical computer scientists continue the search for new quantum algorithms, and have used quantum concepts to prove new results about the classification of computational complexity. Coding theorists have had the new and subtle problem of quantum error correction to analyse and conquer. Most strikingly, the program of experimental physics has been influenced in many directions by Quantum Information Science. State-of-the-art optics experiments transmit quantum states over long distances and perform precision manipulations in single quanta (atomic ions, impurity spins, quantum dots) in the quest to have working quantum cyptography and quantum computing. Quantum Hall systems, and topological insulators, are being assiduously examined for new elementary excitations for use as qubits. In the course of ten years, superconducting devices have improved by over four orders of magnitude in their quantum coherence, a metric made precise by the ideas of quantum computing. [...] DiVincenzo, David
In the last 20 years, there have been lots of novel developments and remarkable achievements in quantum information processing theoretically and experimentally. Among them, the coherent control of nuclear spin dynamics is a powerful tool for the experimental implementation of quantum schemes in liquid and solid nuclear magnetic resonance (NMR) system, especially in liquid-state NMR. Compared with other quantum information processing systems, NMR platform has many advantages such as the long coherence time, the precise manipulation and well-developed quantum control techniques, which make it possible to accurately control a quantum system with up to 12-qubits. Extensive applications of liquid-state NMR spectroscopy in quantum information processing such as quantum communication, quantum computing and quantum simulation have been thoroughly studied over half a century. There are also many outstanding researches in the recent several years. So we focus on the recent researches in this review article. First, we introduce the basic principle of the liquid-state NMR quantum computing and two new methods reported in the pseudo-pure state preparation which has more advantages than the traditional methods. The quantum noise-injection methods and the quantum tomography technology in liquid-state NMR are also mentioned. Then we overview Horrow-Hassidim-Lioyd algorithm, quantum support vector machine algorithm, duality quantum computing and their implementations in liquid-state NMR system. Also, we report recent researches about quantum simulations, including quantum tunneling, high-energy physics and topological sequences. Then we display the quantum cloud platform of our group. In order to let more people, either amateurs or professionals, embrace and more importantly participate in the tidal wave of quantum science, we launch our NMR quantum cloud computing (NMRCloudQ) service. Through NMRCloudQ, we offer a direct access to a real, physical spectrometer in our laboratory and encourage users to explore quantum phenomena and demonstrate quantum algorithms. Finally, we discuss the development prospects and development bottlenecks of NMR, and point out the prospects for the future development direction.
Summary form only given. Quantum mechanics offers the information scientist a new rich resource, which is only recently being tapped to allow for secure communication in the form of quantum cryptography, and for tremendous parallelism in quantum information processing and computing. I will describe developments and prospects for each. Quantum cryptography has already advanced beyond the research laboratory to become a realizable technology with proven secret key distribution for encryption. Quantum computing, although at an earlier stage of development has been recognized as a major new development in physics, enables us (if a quantum computer is realizable) to attack problems previously thought to be too complex for normal computation in a reasonable time. Examples of quantum algorithms involving this kind of advantage are Shor's for fast factorization (in itself a threat to secure communication) and Grover's for database searching. I will discuss the ways quantum mechanics allow such a speed-up, stressing how quantum entanglement is the key resource being exploited, and how quantum gates, networks, and the processors may be implemented in a realistically noisy environment. Simple demonstrators have already been built, and I will discuss prospects for future realization of large-scale processors.
After nearly three decades of rapid development, the quantum information technology in the theoretical and technical studies has gained remarkable achievements. This review gives a brief introduction to the development of various hot research branches of quantum information technology, including quantum cryptography, quantum communication, quantum computing, quantum simulation, quantum metrology, and fundamental theory of quantum information. In addition, this review also discusses various physical systems which have been well applied in the quantum information technology, such as atomic, molecular and optical physics, different branches in solid state physics (superconducting Josephson Junction system, semiconductor quantum dots, Nitrogen-vacancy color centers in diamond), trapped ions, and nuclear magnetic resonance system. With the investigation and accumulation of quantum information technology, the ability to control microscopic world has been significantly improved. Quantum cryptography has been close to the practical application and the long-distance quantum communication has overcome the practical obstacles in principle. Quantum simulation is close to the limit of the classical computer. Also, quantum metrology has gained rapid development. This review not only shows the situation of the international development of quantum information technology, but also highlights the achievements of China in recent years. These achievements demonstrate that China is an indispensable force in the worldwide quantum information community.
In this presentation, an overview of Quantum Information Systems is given. Therefore, the postulates of quantum mechanics are given based on one interpretation that is called the Copenhagen interpretation. The main pillars of quantum mechanics are: Superposition, Interference, and Entanglement. Quantum Information Systems comprise three disciplines: Quantum Computation, Quantum Communication, and Quantum Control. Each one of them has a number of topics with some implementations that have reached the commercial level. Quantum Computation has three models: the circuit model that is using different techniques like superconducting elements and special Silicon-based elements. The Adiabatic quantum model has reached the commercial stage through a start-up company using superconducting chips. The categorical quantum model is based on category theory and one of its main applications is the study and verification of network and cryptographic protocols. Quantum communication started with defining the basic unit of information, the qubit. Then the quantum compression theorem was proved. The quantum channel capacity problem was divided into two problems: transmitting classical information over a quantum channel, and transmitting quantum information over a quantum channel. The first problem was partially resolved. However, the second problem is being researched upon. Two applications will be briefly presented: quantum teleportation and superdense coding. Both of them employs quantum entanglement. Quantum Key Distribution (QKD) using cryptographic protocols has received much attention due its importance in network security. A number of protocols have been proposed and some of them have been implemented, and now a number of commercial products have been announced. Also, some experimental networks have been implemented. QKD using space links have been proposed and experimented with. In few years quantum satellites will be launched. Quantum cryptographic protocols are being proposed to protect infrastructure networks like the electric power grid. Also, it is being used as a countermeasure against global spying networks like ECHELON that are detrimental for national economies. The Quantum Internet is also being considered using quantum teleportation together with Cavity Quantum Electrodynamics with some experimental work going on. Quantum Control is essential for both Quantum Computation and Quantum Communication. Intensive research is going on in: State estimation (called Quantum State Tomography), system identification (called Quantum Process Tomography), and Quantum Feedback Control. The basic concepts will be briefly considered in this presentation. University education has witnessed major changes to support the above developments. At the postgraduate level many universities offer many courses related to the above disciplines. Recently, a number of institutions started to offer undergraduate courses and some of them have even started to introduce Quantum Engineering 4 years undergraduate programs. A brief account will be given to such developments.