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Quantum states are the key mathematical objects in quantum theory. It is therefore surprising that physicists have been unable to agree on what a quantum state represents. There are at least two opposing schools of thought, each almost as old as quantum theory itself. One is that a pure state is a physical property of system, much like position and momentum in classical mechanics. Another is that even a pure state has only a statistical significance, akin to a probability distribution in statistical mechanics. Here we show that, given only very mild assumptions, the statistical interpretation of the quantum state is inconsistent with the predictions of quantum theory....

Progress in atomic, optical and quantum science1, 2 has led to rapid improvements in atomic clocks. At the same time, atomic clock research has helped to advance the frontiers of science, affecting both fundamental and applied research. The ability to control quantum states of individual atoms and photons is central to quantum information science and precision measurement, and optical clocks based on single ions have achieved the lowest systematic uncertainty of any frequency standard3, 4, 5. Although many-atom lattice clocks have shown advantages in measurement precision over trapped-ion clocks6, 7, their accuracy has remained 16 times worse8, 9, 10. Here we demonstrate a many-atom system that achieves an accuracy of 6.4 × 10−18, which is not only better than a single-ion-based clock, but also reduces the required measurement time by two orders of magnitude. By systematically evaluating all known sources of uncertainty, including in situ monitoring of the blackbody radiation environment, we improve the accuracy of optical lattice clocks by a factor of 22. This single clock has simultaneously achieved the best known performance in the key characteristics necessary for consideration as a primary standard-stability and accuracy. More stable and accurate atomic clocks will benefit a wide range of fields, such as the realization and distribution of SI units11, the search for time variation of fundamental constants12, clock-based geodesy13 and other precision tests of the fundamental laws of nature. This work also connects to the development of quantum sensors and many-body quantum state engineering14 (such as spin squeezing) to advance measurement precision beyond the standard quantum limit.

According to the company's wikipedia page, the computer costs $ 10 million. Can we then declare Quantum Computing has officially arrived?! quotes from elsewhere in the site: "first commercial quantum computing system on the market"; "our current superconducting 128-qubit processor chip is housed inside a cryogenics system within a 10 square meter shielded room" Link to the company's scientific publications. Interestingly, this company seems to have been running a BOINC project, AQUA@home, to "predict the performance of superconducting adiabatic quantum computers on a variety of hard problems arising in fields ranging from materials science to machine learning. AQUA@home uses Internet-connected computers to help design and analyze quantum computing algorithms, using Quantum Monte Carlo techniques". List of papers coming out of it.

have to be carefull this article is really badly written. Teleportation is not some matter that disapear from somewhere to reappear somewhere else... Usually we talk about entangled particles (by essence quantum theory is non-local), and teleportation means that if you force (with a measurement) one particle to take a particular quantum state then the other one will have the same quantum state. There it seems that the same could be done with a quantum field, which is the second quantization of the quantum theory: the state of a quantum field can contain a mixture of n-particles states (meaning that the number of particles is not defined, only the mean value). If you measure the number of particle then you force the quantum field to "choose" a particular quantum state (which can be the vacuum). Teleportation means that you will have exactly the same measure on another quantum field, which is somehow intricated to your first one.

"A new Angry Birds-style game is set to help launch a new understanding of quantum science. Some find the concepts of quantum science confusing or unintuitive. Einstein even called quantum effects "spooky." To help people better understand some of the core concepts of quantum science, the Institute for Quantum Computing (IQC) at the University of Waterloo is launching a game - the Quantum Cats" Looking forward to see the ACT winning the Quantum Cats competition :)

Extending quantum communication to space environments would enable us to perform fundamental experiments on quantum physics as well as applications of quantum information at planetary and interplanetary scales. Here, we report on the first experimental study of the conditions for the implementation of the single-photon exchange between a satellite and an Earth-based station. We built an experiment that mimics a single photon source on a satellite, exploiting the telescope at the Matera Laser Ranging Observatory of the Italian Space Agency to detect the transmitted photons. Weak laser pulses, emitted by the ground-based station, are directed toward a satellite equipped with cube-corner retroreflectors. These reflect a small portion of the pulse, with an average of less-than-one photon per pulse directed to our receiver, as required for faint-pulse quantum communication. We were able to detect returns from satellite Ajisai, a low-Earth orbit geodetic satellite, whose orbit has a perigee height of 1485 km.

hello Jose! Interesting it was proposed to do the same with the ISS as part of the ACES experiment. I don't remember the paper but i can look if you're interested

Scientists have discovered how algae that survive in very low levels of light are able to switch on and off a weird quantum phenomenon that occurs during photosynthesis. The function in the algae of this quantum effect, known as coherence, remains a mystery, but it is thought it could help them harvest energy from the sun much more efficiently. Working out its role in a living organism could lead to advances such as better organic solar cells.

very very nice! we tried already a few years back to find an angle to see how we could study quantum phenomena occuring in plants and photosynthsis is one of the great examples since somehow plants manage to make the phenomena work for them at elevated temperatures, a feat in itself ... any good idea most welcome!!!

Anna maybe? Joe?

IBM for the first time ever is making quantum computing available to the public, providing access to a quantum processor via the cloud. Users can create algorithms and run experiments and get inspired by the possibilities of a quantum computer.

Looks interesting.. Have you tried it?

Mathias Troyer from ETH Zurtich gave a talk in Leiden where he showed what he wants to be the replacement to this IBM programming or the best ally of it - program quantum computers with, for instance, python code. Nice developments coming from the quantum coding field, besides the fact we are ages away from a practical quantum computer.

any idea if what the canadians claim to sell is closer to a quantum computer than what they did 2011? (I remember Luzi's comment back then that this had nothing to do with a quantum computer) Canada being member state of ESA ... should we start getting interested?

google paper on quantum computers ... anybody with further insight on how realistic this is

Not an answer to Leopold's question but here is a little primer on quantum computers for those that are (like me) still confused about what they actually do: http://www.dwavesys.com/tutorials/background-reading-series/quantum-computing-primer It give a good intuitive idea of the kinds of problems that an adiabatic quantum computer can tackle, an easy analogy of the computation and an explanation of how this get set up in the computer. Also, there is emphasis on how and why quantum computers lend themselves to machine learning (and maybe trajectory optimization??? - ;-) ).

A theory-SuperDense quantum teleportation-posed by Hampshire College physics professor Herbert Bernstein will be tested on the International Space Station. Theoretical physicist Bernstein devised the SuperDense scheme more than a decade ago in his investigations of different ways to send a quantum state from one part of a laboratory to a remote station.

Anna could you have a closer look into this - we should at least know what they are up to, be able to explain if anybody asks ... I also somehow missed this one in the NIAC study descriptions ... maybe a good moment to have another look at these "This is the second NASA grant for SuperDense quantum teleportation. A grant awarded in 2010 through NASA Innovative Advanced Concepts (NIAC) investigated the viability of the theory and produced the world's first experimental demonstration. Surprising or seminal experiments have marked Bernstein's research career. This is the fourth time a major proposal has become reality; two of his experiments helped found new sub-fields of physics (neutron interferometry and entanglement for quantum information)."

Quoted from one of the authors in a separate interview: "We know that the spin states of atomic nuclei associated with semiconductor defects have excellent quantum properties at room temperature," said Awschalom, Liew Family Professor in Molecular Engineering and a senior scientist at Argonne National Laboratory. "They are coherent, long-lived and controllable with photonics and electronics. Given these quantum 'pieces,' creating entangled quantum states seemed like an attainable goal." Bringing the quantum world to the macroscopic scale could see some interesting applications in sensors, or generally entanglement-enhanced applications.

They were previously working on the same concept in N-V centers in diamond (as a semiconductor). Here the advantage is that SiC could in principle be integrated with Si or Ge. Anyway its all about controlling coherence. In the next 10 years some breakthroughs are expected in the field of semiconductor spintronics, but quantum computing in this way lies still in the horizon

I tried reading the abstract and my eyes glazed over at the buzzword density. Is this hot doo doo or a meaningful result?

wow, quantum, artificial life, biomimetic, quantum supremacy .... quantum machine learning, and quantum artificial intelligence and, wait for it ...... quantum complexity. All in one abstract is this the new champion?

"...the European Commission announced in 2016 that it was investing one billion euros in a research effort known as the Quantum Technology Flagship. The goal for this project is to develop four technologies: quantum communication, quantum simulation, quantum computing, and quantum sensing. After almost two years, how is it going?" arxiv link to the actual report: http://arxiv.org/abs/1712.03773

At its Ignite conference today, Microsoft announced its moves to embrace the next big thing in computing: quantum computing. Later this year, Microsoft will release a new quantum computing programming language, with full Visual Studio integration, along with a quantum computing simulator. With these, developers will be able to both develop and debug quantum programs implementing quantum algorithms.

Basically quantum entanglement, or more accurately the dispersal and expansion of mixed quantum states, results in an apparent flow of time. Quantum information leaks out and the result is the move from a pure state (hot coffee) to a mixed state (cooled down) in which equilibrium is reached. Theoretically it is possible to get back to a pure state (coffee spontaneously heating up) but this statistical unlikelihood gives the appereance of irreversibility and hence a flow o time. I think an interesting question is then: how much useful work can you extract from this system? (http://arxiv.org/abs/1302.2811) It should for macroscopic thermodynamic systems lead to the Carnot cycle, but on smaller scales it might be possible to formulate a more general expression. Anybody interested to look into it? Anna, Jo? :)

What you propose is called Maxwell's demon: http://en.wikipedia.org/wiki/Maxwell%27s_demon Unfortunately (or maybe fortunately) thermodynamics is VERY robust. I guess if you really only want to harness AND USE the energy in a microscopic system you might have some chance of beating Carnot. But any way of transferring harvested energy to a macroscopic system seems to be limited by it (AFAIK).

Quantum-stuff in bio-stuff. Finally! Anyone wants to work on biomimetic quantum theory?

I'll start once we have the "Topological Metabiostring".

ooh yeah! do you have some time on sunday...? well this falls i think in the "Can we use it for space?" category... but I would like to read a bit more about it (just had the time to read the sciencenow news few post below...)

anything happening on this since 3 years?

yes it seems like. most of it seems however directed toward understanding this effect, and not toward applications. But i'm still convinced that we could find many very interesting applications !!! a few references from ADS: 1 2011PhRvA..83f3807B 1.000 06/2011 A E X R C U Brida, G.; Chekhova, M. V.; Fornaro, G. A.; Genovese, M.; Lopaeva, E. D.; Berchera, I. Ruo Systematic analysis of signal-to-noise ratio in bipartite ghost imaging with classical and quantum light 2 2011PhRvA..83e3808L 1.000 05/2011 A E R U Liu, Ying-Chuan; Kuang, Le-Man Theoretical scheme of thermal-light many-ghost imaging by Nth-order intensity correlation 3 2011PhRvA..83e1803D 1.000 05/2011 A E R C U Dixon, P. Ben; Howland, Gregory A.; Chan, Kam Wai Clifford; O'Sullivan-Hale, Colin; Rodenburg, Brandon; Hardy, Nicholas D.; Shapiro, Jeffrey H.; Simon, D. S.; Sergienko, A. V.; Boyd, R. W.; Howell, John C. Quantum ghost imaging through turbulence 4 2011SPIE.7961E.160O 1.000 03/2011 A E T Ohuchi, H.; Kondo, Y. Complete erasing of ghost images caused by deeply trapped electrons on computed radiography plates 5 2011ApPhL..98k1115M 1.000 03/2011 A E R U Meyers, Ronald E.; Deacon, Keith S.; Shih, Yanhua Turbulence-free ghost imaging 6 2011ApPhL..98k1102G 1.000 03/2011 A E R C U Gan, Shu; Zhang, Su-Heng; Zhao, Ting; Xiong, Jun; Zhang, Xiangdong; Wang, Kaige Cloaking of a phase object in ghost imaging 7 2011RScI...82b3110Y 1.000 02/2011 A E R U Yang, Hao; Zhao, Baosheng; Qiu

A system of nine quantum bits (qubits) that is robust to errors that would normally destroy a quantum computation has been created by researchers at the University of California, Santa Barbara (UCSB) and Google. The device relies on a quantum error-correction protocol, which the team says could be deployed in practical quantum computers of the future.

Quantum processes shouldn't survive in hot, wet biological systems and yet a growing body of evidence suggests they do. Now physicists think they know how

Yes, because our bosses forced us to write strategic reports on "system of systems" :-)

Oh these terrible ignorant slave masters .... Would love to see your "reports on system of systems" :-)