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NQIT researchers demonstrate ‘hybrid’ logic gate as work towards quantum computer continues

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NQIT researchers demonstrate ‘hybrid’ logic gate as work towards quantum computer continues

Since it began in 2014, the Networked Quantum Information Technologies Hub has been focusing on developing quantum technologies that could dwarf the processing power of today’s supercomputers and now a new paper by Oxford researchers, published in the journal Nature, demonstrates how the work of the Hub is progressing.

Professor David Lucas of Oxford’s Department of Physics, co-leader, with Professor Andrew Steane, of the ion trap quantum computing group, explains: ‘The development of a “quantum computer” is one of the outstanding technological challenges of the 21st century. A quantum computer is a machine that processes information according to the rules of quantum physics, which govern the behaviour of microscopic particles at the scale of atoms and smaller.

‘An important point is that it is not merely a different technology for computing in the same way our everyday computers work; it is at a very fundamental level a different way of processing information. It turns out that this quantum-mechanical way of manipulating information gives quantum computers the ability to solve certain problems far more efficiently than any conceivable conventional computer. One such problem is related to breaking secure codes, while another is searching large data sets. Quantum computers are naturally well-suited to simulating other quantum systems, which may help, for example, our understanding of complex molecules relevant to chemistry and biology.’

One of the leading technologies for building a quantum computer is trapped atomic ions, and a principal goal of the NQIT project is to develop the constituent elements of a quantum computer based on these ions.

Professor Lucas, of Balliol College, says: ‘Each trapped ion (a single atom, with one electron removed) is used to represent one “quantum bit” of information. The quantum states of the ions are controlled with laser pulses of precise frequency and duration. Two different species of ion are needed in the computer: one to store information (a “memory qubit”) and one to link different parts of the computer together via photons (an “interface qubit”).’

The Nature paper, whose lead author is Chris Ballance, a Junior Research Fellow at Magdalen College, demonstrates the all-important quantum ‘logic gate’ between two different species of ion – in this case two isotopes of calcium, the abundant isotope calcium-40 and the rare isotope calcium-43.

Professor Lucas says: ‘The Oxford team has previously shown that calcium-43 makes the best single-qubit memory ever demonstrated, across all physical systems, while the calcium-40 ion has a simpler structure which is well-suited for use as an “interface qubit”. The logic gate, which was first demonstrated for same-species ions at NIST Boulder (USA) in 2003, allows quantum information to be transferred from one qubit to another; in the present work, the qubits reside in the two different isotopes, stored in the same ion trap. The Oxford work was the first to demonstrate that this type of logic gate is possible with the demanding precision necessary to build a quantum computer.

‘In a nice piece of “spin-off science” from this technological achievement, we were able to perform a “Bell test”, by first using the high-precision logic gate to generate an entangled state of the two different-species ions, then manipulating and measuring them independently. This is a test which probes the non-local nature of quantum mechanics; that is, the fact that an entangled state of two separated particles has properties that cannot be mimicked by a classical system. This was the first time such a test had been performed on two different species of atom separated by many times the atomic size.’

While Professor Lucas cautions that the so-called ‘locality loophole’ is still present in this experiment, there is no doubt the work is an important contribution to the growing body of research exploring the physics of entanglement. He says: ‘The significance of the work for trapped-ion quantum computing is that we show that quantum logic gates between different isotopic species are possible, can be driven by a relatively simple laser system, and can work with precision beyond the so-called “fault-tolerant threshold” precision of approximately 99% – the precision necessary to implement the techniques of quantum error correction, without which a quantum computer of useful size cannot be built.’

In the long term, it is likely that different atomic elements will be required, rather than different isotopes. In closely related work published in the same issue of Nature, by Ting Rei Tan et al, the NIST Ion Storage group has demonstrated a different type of quantum logic gate using ions of two different elements (beryllium and magnesium).

The Oxford experiments were designed and carried out by graduate students Chris Ballance and Vera Schäfer, following a proposal of Jonathan Home and David Lucas, using an apparatus developed by all members of the research team.

See also Chris Ballance’s DPhil thesis, available online.

This article originally appeared on the Oxford University Science blog – read the original here.

Source: https://www.nqit.ox.ac.uk/news/nqit-researchers-demonstrate-hybrid-logic-gate-work-towards-quantum-computer-continues

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Quantum

Sure, The Goop Lab Is Absurdbut It Also Offers Hope

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The first episode of The Goop Lab, Gwyneth Paltrow’s new Netflix show, opens in Jamaica. The sun beams, the crystalline water sparkles, and a group of Goop staffers sit cross-legged in a circle, like schoolchildren poised for a read-aloud. Then, under the supervision of three “psychedelic elders,” they each drink a mug of psilocybin tea.

It’s fitting that the series begins this way. The following episodes, each meant to explore the “ideas that may seem out-there or too scary,” feel a bit like navigating the surrealism of psychedelics. There are moments of absurdity, moments of poignancy. A woman is brought to tears by a psychic reading that involves a donkey; in another episode, a series of vulva portraiture flashes onscreen. By the end, the viewer may feel the way one Goop staffer describes feeling after the work-sponsored mushroom trip: “really drained, physically and emotionally.”

Since it began as an email newsletter in 2008, the Goop brand has become well-established for championing the unestablished. The products sold on its website include, among other things, a mustard seed detox bath, an aromatic spray for psychic vampires, and a supplement called Brain Dust. In 2017, the watchdog group Truth in Advertising filed a complaint with two district attorneys at the California Food, Drug and Medical Device Task Force asking the regulators to look into Goop’s claims about more than 50 of its products, including its vaginal eggs, which the Goop site suggested could “increase vaginal muscle tone, hormonal balance, and feminine energy in general.” As a result, the company agreed to pay a $145,000 fine and submit to a five-year injunction, during which Goop promised not to say its products have "sponsorship, approval, characteristics, ingredients, uses or benefits which they do not have.”

The Netflix show uses this skepticism as a runway. This isn’t science—it’s something much more lucrative. “We’re here one time, one life,” Paltrow says in the first episode, addressing her staffers from the Goop headquarters in Santa Monica, California. “How can we really milk the shit out of this?” She’s referring to the show’s approach to self-optimization, but could just as easily be talking about her business strategy.

As a multimillion-dollar business, Goop has perfected the art of manufacturing hope. Modern-day anxieties go in (stress, lack of desire, an undiagnosable medical condition) and out comes a strange but sellable solution (herbal supplements, crystals, reiki). The Goop Lab follows this formula as well. Each episode unpacks a controversial wellness idea—cold therapy, energy healing, orgasm coaching, psychic communication, dieting for longevity, and psychedelic medicine—and explores its merits with expert interviews, case studies, and a stunt from the Goop staffers. Many of these staffers out themselves as skeptics, talking on camera about how they do not believe in psychic mediumship or energy healing. In that sense, few of the episodes come off as outright endorsements. Then again, Paltrow and her staff don’t do much to counterbalance or fact-check the claims of the experts they invite on the show. To that end, it’s worth mentioning that each episode includes a disclaimer: The show is meant to “entertain and inform, not provide medical advice.”

Paltrow’s colleagues call her GP, which abbreviates her name but also doubles for “guinea pig.” On the show, she tries several of the controversial wellness practices herself—like a five-day fast and, in one rather frightening scene, a facial that involves needling her own blood plasma back into her face. Mostly, though, Paltrow saves herself from much on-screen embarrassment. For those experiments, she sends her staff.

The Goop staff goes to Jamaica for the supervised psilocybin trip. They go to Lake Tahoe to practice hyperventilating and submerging themselves in freezing-cold water. They take erotic portraits in a workshop about sensuality, and they take turns reading each others’ psychic energies with a medium. Even though Goop staffers express skepticism, science and pseudoscience are woven so tightly together on the show that it’s difficult to find the seams.

Timothy Caulfield, who researches health law and policy at the University of Alberta, has called this the “the wellness version of fake news” and “an infomercial for the gestalt that is Goop.” (Caulfield is also the author of the 2016 book Is Gwyneth Paltrow Wrong About Everything? in which he seems to conclude, basically, yes.) Paltrow and her staffers occasionally raise their eyebrows at the claims made onscreen, but mostly, they are game to participate and promote the theories in each episode. Caulfield says that’s for one obvious reason: Goop, the company, stands to profit from them.

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“People are frustrated with how they’re treated by the conventional system, and feel like their needs are not being listened to,” says Caulfield. “But an entity like Goop is exploiting a real problem in order to sell pseudoscience. It’s a for-profit company. It’s doing these things in order to build a brand.”

The show has its fair share of “junk science, gibberish, and unproven health claims from snake-oil-salesmen guests,” as some reviews have pointed out. But there are reputable experts who share real science, too. The first episode, about the benefits of psychedelics, features an interview with Mark Haden, the executive director of MAPS Canada. MAPS, or the Multidisciplinary Association for Psychedelic Studies, works closely with the FDA and promotes academic research and clinical studies around the therapeutic potential of psychedelics. Another episode, on female orgasm, features Betty Dodson, the 90-year-old sex educator whose work has been instrumental in understanding pleasure.

Those moments of lucidity can make it difficult to parse what’s real and what’s not. (Caulfield has a term for this thin veneer of credibility: “We call it ‘scienceploitation.’”) In some cases, like the episode about psychedelics, the show conflates the real science with the anecdotal experience of the Goop staffers in Jamaica. Other times, the effect is more absurd. In an episode about energy healing, a body healer cites the “double slit experiment” from quantum mechanics to credentialize his work—a practice that involves waving his hands like a puppeteer above a person’s body to release the energy that’s “trapped” in the fascia and can cause pain, disease, and emotional unrest.

What the show does most candidly, though, is shine a light on the desperation people feel when science cannot understand their pain. Throughout the series, we meet a Goop staffer suffering from a panic disorder, another who’s dealing with the trauma of her father’s suicide, and another who has trouble with intimacy since coming out as gay. Between the interviews and the staff stunts, there are various “case studies,” like a veteran who tried to kill himself multiple times before finding MDMA-assisted therapy. If The Goop Lab is an informercial for the products it sells, it’s also a portrait of the average Goop aficionado. They’ve been failed by everything else; if a $300 crystal can make them feel better, why not try?

If anyone stands to gain from The Goop Lab, though, it’s not the viewers, or the staffers who jump at the chance to go on a 'shroom trip. It’s the people whose products and alternative therapies are showcased on screen, each of whom can expect a sizable dose of interest after the exposure from Paltrow’s show. After watching so many of Goop’s staffers open up about their personal challenges and traumas, it’s hard not to root for them to find a little peace. If energy healing does the trick, well, so be it.


Read more: https://www.wired.com/story/the-goop-lab-review/

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Quantum

New guidelines for the allocation of Partnership Resource

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The Hub has today published new guidelines for the allocation of its flexible funding, the so-called Partnership Resource. We welcome proposal submissions for a period of six weeks (till March 8th, 2020). Funding decisions will be communicated to all successful applicants during the w/c 23/03/20. For more information on the nature of the partnership resource funding, the kind of projects supported in the past, and to download the guidelines, visit the Partnership Resource section of the website here.

Source: https://www.quantumcommshub.net/news/new-guidelines-for-the-allocation-of-partnership-resource/

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Scientists gain new visibility into quantum information transfer

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When we talk about “information technology,” we generally mean the technology part, like computers, networks, and software. But information itself, and its behavior in quantum systems, is a central focus for MIT’s interdisciplinary Quantum Engineering Group (QEG) as it seeks to develop quantum computing and other applications of quantum technology.

A QEG team has provided unprecedented visibility into the spread of information in large quantum mechanical systems, via a novel measurement methodology and metric described in a new article in Physics Review Letters. The team has been able, for the first time, to measure the spread of correlations among quantum spins in fluorapatite crystal, using an adaptation of room-temperature solid-state nuclear magnetic resonance (NMR) techniques.

Researchers increasingly believe that a clearer understanding of information spreading is not only essential to understanding the workings of the quantum realm, where classical laws of physics often do not apply, but could also help engineer the internal “wiring” of quantum computers, sensors, and other devices.

One key quantum phenomenon is nonclassical correlation, or entanglement, in which pairs or groups of particles interact such that their physical properties cannot be described independently, even when the particles are widely separated.

That relationship is central to a rapidly advancing field in physics, quantum information theory. It posits a new thermodynamic perspective in which information and energy are linked — in other words, that information is physical, and that quantum-level sharing of information underlies the universal tendency toward entropy and thermal equilibrium, known in quantum systems as thermalization.

QEG head Paola Cappellaro, the Esther and Harold E. Edgerton Associate Professor of Nuclear Science and Engineering, co-authored the new paper with physics graduate student Ken Xuan Wei and longtime collaborator Chandrasekhar Ramanathan of Dartmouth College.

Cappellaro explains that a primary aim of the research was measuring the quantum-level struggle between two states of matter: thermalization and localization, a state in which information transfer is restricted and the tendency toward higher entropy is somehow resisted through disorder. The QEG team’s work centered on the complex problem of many-body localization (MBL) where the role of spin-spin interactions is critical.

The ability to gather this data experimentally in a lab is a breakthrough, in part because simulation of quantum systems and localization-thermalization transitions is extremely difficult even for today’s most powerful computers. “The size of the problem becomes intractable very quickly, when you have interactions,” says Cappellaro. “You can simulate perhaps 12 spins using brute force but that’s about it — far fewer than the experimental system is capable of exploring.”

NMR techniques can reveal the existence of correlations among spins, as correlated spins rotate faster under applied magnetic fields than isolated spins. However, traditional NMR experiments can only extract partial information about correlations. The QEG researchers combined those techniques with their knowledge of the spin dynamics in their crystal, whose geometry approximately confines the evolution to linear spin chains.

“That approach allowed us to figure out a metric, average correlation length, for how many spins are connected to each other in a chain,” says Cappellaro. “If the correlation is growing, it tells you that interaction is winning against the disorder that’s causing localization. If the correlation length stops growing, disorder is winning and keeping the system in a more quantum localized state.”

In addition to being able to distinguish between different types of localization (such as MBL and the simpler Anderson localization), the method also represents a possible advance toward the ability to control of these systems through the introduction of disorder, which promotes localization, Cappellaro adds. Because MBL preserves information and prevents it from becoming scrambled, it has potential for memory applications.

The research’s focus “addresses a very fundamental question about the foundation of thermodynamics, the question of why systems thermalize and even why the notion of temperature exists at all,” says former MIT postdoc Iman Marvian, who is now an assistant professor in Duke University’s departments of Physics and Electrical and Computer Engineering. “Over the last 10 years or so there’s been mounting evidence, from analytical arguments to numerical simulations, that even though different parts of the system are interacting with each other, in the MBL phase systems don’t thermalize. And it is very exciting that we can now observe this in an actual experiment.”

“People have proposed different ways to detect this phase of matter, but they’re difficult to measure in a lab,” Marvian explains. “Paola’s group studied it from a new point of view and introduced quantities that can be measured. I’m really impressed at how they’ve been able to extract useful information about MBL from these NMR experiments. It’s great progress, because it makes it possible to experiment with MBL on a natural crystal.”

The research was able to leverage NMR-related capabilities developed under a previous grant from the US Air Force, says Cappellaro, and some additional funding from the National Science Foundation. Prospects for this research area are promising, she adds. “For a long time, most many-body quantum research was focused on equilibrium properties. Now, because we can do many more experiments and would like to engineer quantum systems, there’s much more interest in dynamics, and new programs devoted to this general area. So hopefully we can get more funding and continue the work.”


Source: http://news.mit.edu/2018/mit-qeg-develops-unprecedented-visibility-quantum-information-transfer-0308

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