18:00 - 19:30
- Wallenberg Research Centre
You are cordially invited to attend the next public STIAS lecture of 2018. This presents an opportunity to academics, researchers and students at universities of the Western Cape, as well as members of the public, to learn more about the work of STIAS fellows and associates.
Seating for the event is limited and must be reserved in advance:
RSVP by 12h00 on Thursday 1 November with Ms Nel-Mari Loock
On this occasion Professor Jian-Wei Pan, Director: Division of Quantum Physics and Quantum Information at the University of Science and Technology of China, Hefei will present a talk with the title:
From Einstein’s Curiosity to New Quantum Technologies
This event will be streamed live at https://www.youtube.com/channel/UCNCAcXCVa1QjpO8q3OpIQ5w
Quantum information science and technology are emerging and fascinating technologies formed by combining coherent manipulating of individual quantum systems and information technology. This enables secure quantum cryptography (quantum communication), super-fast quantum computing, revealing the laws of complex physical systems (quantum simulation), and improving measurement precision (quantum metrology) to beat classical limits. This presentation will highlight some of our progress with quantum communication, quantum computing, quantum simulation and quantum metrology, based on photons and atoms.
From a fundamental point of view one is led to the concept of quantum entanglement as applied to the quantum superposition principle for a multi-particle system. The associated ‘spooky action at a distance’ phenomena referred to by Einstein, is often explained by the seemingly reasonable assumptions of “local realism”. In this context the inequalities proposed by John Bell and others provide immediate tests for the correctness of quantum mechanics. Many efforts address loophole-free experimental tests of Bell’s inequalities, attempting to close various loopholes; some are still to be settled, including the freedom of choice loophole.
Tests are on-going, but already developed ground-breaking technologies for coherent manipulation of quantum systems offer elegant and feasible solutions to the increasing needs for computational power and information security. Based on state-of-the-art fiber technology and rich fiber resources, we have managed to achieve prevailing quantum communication with realistic devices in a real-life situation. This includes developing a decoy state scheme over 100 km fibre, extending its employment to a metropolitan area network, as well as maintaining Measurement Device Independent Quantum Key Distribution (MDI-QKD) over 400km. We are also developing practically useful quantum repeaters that combine entanglement swapping, entanglement purification, and efficient and long-lived quantum memory for ultra-long distance quantum communication.
Another goal is to attain global quantum communication via satellite. We have spent the past decade performing systematic ground tests for satellite-based quantum communication. Our efforts finally ensured the successful launch of the Micius satellite which very recently was operated as a trustful relay for intercontinental QKD between Beijing and Vienna over a distance of 7600 km.
Future prospects include building a global quantum communication infrastructure with satellite and fiber networks, quantum computing through coherent manipulation of more than 50 qubits to exceed the simulating power of the best current supercomputers, reaching “quantum supremacy”, and a Bell-test experiment with a human as observer at a distance of the order of one light-second.
Jian-Wei Pan is Director: Division of Quantum Physics and Quantum Information at the University of Science and Technology of China in Hefei and holds a PhD from the University of Vienna (1999). During his early career in Austria as a PhD student and later as a senior scientist, Pan and his colleagues achieved a seminal series of breakthroughs in quantum communication. His first quantum teleportation experiment reported in 1997 was selected by Nature as one of the 21 classic papers in physics published by Nature in 20th Century. Pan performed the first entanglement swapping experiment, which was later selected by Science magazine as one of the top ten breakthroughs of 1998. These experiments established the fascinating scientific possibility of transferring quantum states of one object to another over arbitrarily long distances in a disembodied way, ie without physically transporting the object itself.
He has focused on developing experimental methods to coherently control multiple photons for the creation of multiparticle entanglement – a concept first recognized by Einstein, Schrödinger et al. and is at the heart of quantum physics. He has developed the world’s first three- and four-photon entanglement, and used them to perform the first Greenberger-Horne-Zeilinger experiment that showed stark contradictions between Einstein’s local hidden variable theory and quantum mechanics. He theoretically proposed, and experimentally demonstrated his own idea of entanglement purification of arbitrarily noisy entangled state using only linear optics. These work offers a powerful tool to beat the undesired abundant decoherence effects for achieving long-distance quantum communication and scalable quantum computation.
Pan was appointed as Yangtze Chair Professor of Physics by the Chinese Ministry of Education in 2002. There he brought research on quantum information science in China to a world leading level. He accumulated records for creating the world’s first five-, six-, eight-, and ten-photon entanglement. Pan has developed the first s-shell pulsed resonant excitation method—the cleanest way—to generate single photons with near-unity indistinguishability, which is now adopted by nearly all the leading groups worldwide. By combining with solid-state cavity-QED, he created the first single-photon source that simultaneously combines near-perfect single-photon purity, indistinguishability, and efficiency (selected as Optics in 2016 by OPN), opening the way to multi-photon experiments with semiconductor quantum dots. These experiments gave rise to further technologies for new quantum information protocols, such as optical quantum computation.
Pan and his team realized many fundamental concepts for the first time, including the realization of non-destructive quantum controlled-NOT gates, Shor’s factoring algorithm, loss-tolerant quantum encoding, topological quantum error correction, quantum simulation of anyonic fractional statistics in the Kitaev model, solving systems of linear equations, and entanglement-based quantum machine learning. Recently, exploiting his state-of-the-art single-photons sources, he has realized boson-sampling with up to five photons with efficiencies >24,000 times higher than the previous work. This is the first single-photon quantum device which reaches a computational complexity that can beat early classical computers such as ENIAC and TRADIC.
Pan and his group continue the scientific dream of quantum teleportation and brought it to conceptually and technologically new levels. Taking advantage of the developed five-photon entanglement, his team demonstrated a so-called open-destination teleportation where the teleported state is encoded to multiple particles at different locations and could be eventually read out from any one of them. The team also made the first attempts to increase the capacity of teleportation from one particle to two particles, and from photon’s one degree of freedom only to simultaneously multiple internal properties of quantum particles, selected as Physics World 2015 “Breakthrough of the Year”.
One of the most important goals of Pan’s research efforts is to achieve technologically useful long-distance secure quantum communication on a global scale. A straightforward approach of fibre-based quantum key distribution (QKD) is ultimately limited to a few hundred kilometres. At 1000 km, even with a perfect 10-GHz single-photon source, ideal detectors and 0.2 dB/km fibre losses one would detect only 0.3 photon on average per century. Consequently, futuristic continental scale quantum communication demands radically different technologies. There are two main routes: quantum repeaters and through satellite; remarkably, Pan has been the unquestionable leader for both.
For the first time, Pan and his team used the decoy-state QKD protocol to close the loophole of imperfect photon source, and used the measurement-device-independent QKD protocol to close the loophole of imperfect photon detectors—two most important loopholes in quantum cryptograph. To overcome the photon loss in fibre, Pan and his team have been the first to realize entanglement swapping, entanglement purification, and quantum memory, and combined them as quantum repeaters. Pan’s group has created the best performance quantum repeater nodes with both long storage time and high retrieval efficiency that can support quantum communications at 500 km, a regime inaccessible with conventional methods. Meanwhile, Pan has been pushed these techniques to move out of the laboratories and enter real-world applications. His team constructed an all-pass-type metropolitan quantum communication networks in Beijing, Jinan, Hefei and Shanghai in China. Very recently, his team has successfully accomplished the project of building world’s biggest quantum secure communication backbone, from Beijing to Shanghai, with a distance exceeding 2000 km. Based on this, currently real-world applications by banks, securities and insurance are on trial.
The second parallel line of Pan’s pursuit of practically useful QKD is satellite-based global quantum communication, taking advantage of the negligible photon loss and decoherence in the atmosphere. In 2005, Pan’s team managed to distribute entangled photon pairs over a noisy ground atmosphere of 13 km in Hefei city. It has been shown for the first time that the desired entanglement can still survive after both entangled photons have passed through the noisy ground atmosphere with a distance beyond the effective thickness of the aerosphere. In 2010, the team demonstrated entanglement distribution and teleportation on the Great Wall of China over a distance of 16 km. Two years later, at Qinghai Lake China the team achieved the distribution of entangled photons over a two-link free-space channel to two receivers separated by more than 100 km. On August 2016, Pan and his team have successfully launched the first Quantum Science Satellite, which has accomplished three key milestone for a global-scale quantum internet: establishment of the first secure QKD from the satellite to the ground with KHz rate over thousands kilometres distance, which is about 20 orders of magnitudes more efficient than using telecommunication optical fibres; satellite-based distribution and survival of entanglement between two photons to two locations on Earth separated by 1205 km and test of the contradiction between Einstein’s local realism and quantum mechanics for the first time at space-scale, and quantum teleportation from ground to satellite over 1400 km. The Quantum Science Satellite will later be used for intercontinental connections to ground stations in Austria, Italy, Germany and Canada, and will provide a platform for fundamental quantum optics experiments at distances that have previously been inaccessible on the ground.
Pan has authored more than 190 articles, including 14 in Nature/Science and 24 in Nature Physics/Nature Photonics/Nature Nanotechnology. His work in the field of quantum information and quantum communication has been selected by Nature in “A celebration of Physics” (1999), as “Feature of the year” (2012), and “the science events that shaped the year” (2016), by Science as “Breakthrough of the year” (1998), by the American Physical Society as “The top physics stories of the year” (5 times), by the Institute of Physics as “Breakthrough of the year” or “Highlights of the year” (6 times), and by Scientific American as “2016 World Changing Ideas”.
Jian-Wei Pan is currently a Professor of Physics of University of Science and Technology of China, an Academician of Chinese Academy of Sciences (CAS), and a Fellow of the World Academy of Sciences (TWAS). He serves as the Director of the CAS Centre for Excellence and Innovation in Quantum Information and Quantum Physics, and the Chief Scientist for the Quantum Science Satellite Project, and the Beijing-to-Shanghai 2000-km Quantum Communication Backbone Project