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classifieds-marketing-news · 5 months ago

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Biggest movers before the market opens: Abercrombie & Fitch, Pinterest, Hilton Grand Vacations

Top News in the Stock Market Today Quantum Stocks Plunge After Zuckerberg's Comments Quantum stocks took a hit following remarks from Mark Zuckerberg and Nvidia CEO Jensen Huang, with Rigetti Computing and D-Wave Quantum seeing significant drops. Managed Care Stocks on the Rise Managed care stocks saw gains after the US government proposed a reimbursement rate increase for Medicare Advantage plans, with Humana, UnitedHealth, and CVS Health all rising. Boot Barn Guides Higher Boot retailer Boot Barn's guidance for third-quarter earnings exceeded expectations, leading to a 4% jump in its stock price. Pinterest Slides After Downgrade Pinterest shares dropped after a downgrade from Jefferies, citing underwhelming growth forecasts for the company. Crypto Stocks Decline with Bitcoin Stocks tied to the price of bitcoin fell as the cryptocurrency dipped, affecting companies like Coinbase and MicroStrategy. Lululemon Sees Strong Demand Lululemon reported strong holiday sales, leading to a 3% increase in shares and an upward revision of its sales and earnings guidance. Macy's Issues Lackluster Guidance Macy's shares fell after issuing a disappointing update to its fourth-quarter guidance, with revenue expected to fall below previous estimates. Abercrombie & Fitch Raises Outlook Despite a plunge in premarket trading, Abercrombie & Fitch raised its fourth-quarter sales outlook on strong holiday sales expectations. Howard Hughes Holdings Soar Shares of real estate developer Howard Hughes Holdings jumped 9% after a proposal from Bill Ackman's Pershing Square for a new entity merger. Tech Stocks Tumble as Treasury Yields Rise Megacap tech stocks like Nvidia, Tesla, and Palantir Technologies saw losses as US Treasury yields increased. Moderna Lowers Sales Guidance Biotech firm Moderna saw a 20% drop after lowering its 2025 sales guidance, citing potential headwinds in the coming year. Intra-Cellular Therapies Acquired by Johnson & Johnson Intra-Cellular Therapies' stock surged after an announcement of an acquisition by Johnson & Johnson for $132 per share. Contributing reporting by Michelle Fox, Alex Harring, Yun Li, Tanaya Macheel, Sarah Min, Jesse Pound, and Pia Singh. #Money #Abercrombie #AbercrombieFitchCo #Biggest #BootBarnHoldingsInc #breakingnews #BreakingNewsMarkets #BroadcomInc #Business #businessnews #CoinbaseGlobalInc #CoreScientificInc #CVSHealthCorp #DPCMCapitalInc #economy #Fitch #Grand #Hilton #HumanaInc #IntraCellularTherapiesInc #IONQInc #JohnsonJohnson #LululemonAthleticaInc #MacysInc #MarathonDigitalHoldingsInc #market #MarketInsider #markets #MetaPlatformsInc #MicronTechnologyInc #MicrostrategyInc #ModernaInc #movers #NVIDIACorp #opens #PalantirTechnologiesInc #Pinterest #PinterestInc #QuantumComputingInc #regwallmarketmovers #RigettiComputingInc #Stockmarkets #TeslaInc #UnitedHealthGroupInc #vacations #WD40Co https://tinyurl.com/2anpls3u

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sciencespies · 4 years ago

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How Close Are We To The Holy Grail Of Room-Temperature Superconductors?

https://sciencespies.com/news/how-close-are-we-to-the-holy-grail-of-room-temperature-superconductors/

How Close Are We To The Holy Grail Of Room-Temperature Superconductors?

One of the biggest physical problems in modern society is resistance. Not political or social resistance, mind you, but electrical resistance: the fact that you cannot send an electrical current through a wire without some of that energy getting lost, being dissipated into heat. Electrical currents are just electric charges that move over time, and are harnessed by humans to move through current-carrying wires. Yet even the best, most effective conductors — copper, silver, gold, and aluminum — all have some resistance to current passing through them. No matter how wide, shielded, or unoxidized these conductors are, they’re never 100% efficient at transporting electrical energy.

Unless, that is, you can make your current-carrying wire go from a normal conductor to a superconductor. Unlike normal conductors, where the resistance gradually lowers when you cool them down, a superconductor has its resistance plummet to zero below a certain critical threshold. Without any resistance, superconductors can transmit electrical energy in a lossless fashion, leading to the holy grail of energy efficiency. Recent developments have brought about the highest-temperature superconductor ever discovered, but we probably won’t be transforming our electronics infrastructure anytime soon. Here’s the science of what’s going on at the frontiers.

One of Faraday’s 1831 experiments demonstrating induction. The liquid battery (right) sends an … [+] electric current through the small coil (A). When it is moved in or out of the large coil (B), its magnetic field induces a momentary voltage in the coil, which is detected by the galvanometer. As the temperature decreases, the resistance of the circuit decreases as well.

J. Lambert

Superconductivity has a long and fascinating history. We realized back in the 19th century that all materials — even the best conductors — still exhibit some sort of electrical resistance. You can lower the resistance by increasing the cross-section of your wire, by lowering the temperature of your material, or by decreasing the length of your wire. However, no matter how thick you make your wire, how cold you cool your system, or how short you make your electric circuit, you can never achieve infinite conductivity with a standard conductor for a surprising reason: electrical currents create magnetic fields, and any change in your resistivity will change the current, which in turn will change the magnetic field inside your conductor.

Yet perfect conductivity requires that the magnetic field inside your conductor not change. Classically, if you do anything to decrease the resistance of your conducting wire, the current will increase, and the magnetic field will change, meaning you can’t achieve perfect conductivity. But there’s an inherently quantum effect — the Meissner effect — that can arise for certain materials: where all magnetic fields inside a conductor are expelled. This makes the magnetic field inside your conductor zero for any current that flows through it. If you expel your magnetic fields, your conductor can begin behaving as a superconductor, with zero electrical resistance.

Helium’s unique elemental properties, such as its liquid nature at extremely low temperatures and … [+] its superfluidic properties, make it well-suited to a series of scientific applications that no other element or compound can match. The superfluid helium shown here is dripping because there is no friction in the fluid to keep it from creeping up the sides of the container and spilling over, which it does spontaneously.

Alfred Leitner

Superconductivity was discovered way back in 1911, when liquid helium first came into widespread use as a refrigerant. Scientist Heike Onnes was using liquid helium to cool down the element mercury into its solid phase, and was then studying the properties of its electrical resistance. Just as expected, for all conductors, the resistance gradually dropped as the temperature dropped, but only up until a point. Abruptly, at a temperature of 4.2 K, the resistance completely disappeared. Moreover, there was no magnetic field present inside the solid mercury once you crossed below that temperature threshold. Later only, several other materials were shown to exhibit this superconductivity phenomenon, all becoming superconductors at their own unique temperatures:

lead at 7 K,

niobium at 10 K,

niobium nitride at 16 K,

and many other compounds subsequently. Theoretical advances accompanied them, helping physicists understand the quantum mechanisms that cause materials to become superconducting. After a series of experiments in the 1980s, however, something fascinating began to occur: materials composed of vastly different types of molecules not only exhibited superconductivity, but some did so at significantly higher temperatures than the earliest known superconductors.

This figure shows the development and discovery of superconductors and their critical temperatures … [+] over time. The different colors represent different types of materials: BCS (dark green circle), Heavy-fermions-based (light green star), Cuprate (blue diamond), Buckminsterfullerene-based (purple inverted triangle), Carbon-allotrope (red triangle), and Iron-pnictogen-based (orange square). The novel states of matter achieved at high pressures have led to the current records.

Pia Jensen Ray. Figure 2.4 in Master’s thesis, “Structural investigation of La2–xSrxCuO4+y – Following staging as a function of temperature”. Niels Bohr Institute, Faculty of Science, University of Copenhagen. Copenhagen, Denmark, November 2015. DOI:10.6084/m9.figshare.2075680.v2

It started with a simple class of materials: copper oxides. In the mid-1980s, experiments with copper oxides with the elements lanthanum and barium broke the longstanding temperature record by several degrees, being found to superconduct at temperatures greater than 30 K. That record was quickly broken by using strontium instead of barium, and then was broken once again — by a significant margin — by a new material: Yttrium-Barium-Copper-Oxide.

This wasn’t just a standard advance, but rather a huge leap: instead of superconducting at temperatures below ~40 K, which meant that either liquid hydrogen or liquid helium was required, Yttrium-Barium-Copper-Oxide became the first material discovered to superconduct at temperatures above 77 K (it superconducts at 92 K), meaning that you could use the much cheaper liquid nitrogen to cool your device down to superconducting temperatures.

This discovery led to an explosion of superconductivity research, where a variety of materials were introduced and explored, and not only extreme temperatures but also extreme pressures were applied to these systems. Despite the huge explosion in research surrounding superconductivity, however, the maximum superconductivity temperature stagnated, failing to crack the 200 K barrier (while room temperature is just a hair under 300 K) for decades.

Still image of a liquid nitrogen cooled puck, superconducting above a magnetic track. By creating a … [+] track where the outside magnetic rails point in one direction and the inside magnetic rails point in the other, a Type II superconducting object will levitate, remained pinned above-or-below the track, and will move along it. This could, in principle, be scaled up to allow resistance-free motion on large scales if room-temperature superconductors are achieved.

Henry M��hlpfordt / TU Dresden

Nevertheless, superconductivity has become incredibly important in enabling certain technological breakthroughs. It’s widely used in the creation of the strongest magnetic fields on Earth, which are all made through superconducting electromagnets. With applications ranging from particle accelerators (including the Large Hadron Collider at CERN) to diagnostic medical imaging (they’re an essential component of MRI machines), superconductivity isn’t just itself a fascinating scientific phenomenon, but one that enables some excellent science.

While most of us are probably more familiar with the fun and novel applications of superconductivity — such as using those strong magnetic fields to levitate frogs or taking advantage of superconductivity to make frictionless pucks levitating above and sliding across magnetic tracks — that’s not really the societal goal. The goal is to create an electrified infrastructure system for our planet, from power lines to electronics, where electrical resistance is a thing of the past. While some cryogenically cooled systems currently leverage this, a room-temperature superconductor could lead to an energy-efficiency revolution, as well as infrastructure revolutions in applications such as magnetically levitated trains and quantum computers.

A modern high field clinical MRI scanner. MRI machines are the largest medical or scientific use of … [+] helium today, and make use of quantum transitions in subatomic particles. The intense magnetic fields achieved by these MRI machines rely on field strengths that can only be achieved with superconducting electromagnets, at present.

Wikimedia Commons user KasugaHuang

In 2015, scientists took a relatively simple molecule — hydrogen sulfide (H2S), a molecule very analogous to water (H2O) — and applied an incredible pressure to it: 155 gigapascals, which is over 1500000 times the pressure of Earth’s atmosphere at sea level. (For comparison, this would be like applying more than 10,000 tonnes of force to every square inch of your body!) For the first time, the 200 K barrier was cracked, but only under these extremely pressurized conditions.

This line of research was so promising that many physicists who had become disillusioned with the prospect of achieving a practical solution to the superconductivity questioned took it up once again with renewed interest. In the October 14, 2020 issue of Nature, University of Rochester physicist Ranga Dias and his colleagues mixed hydrogen sulfide, hydrogen, and methane under extreme pressures: ~267 gigapascals, and were able to create a material — a “photochemically transformed carbonaceous sulfur hydride system” — that shattered the temperature record for superconductors.

For the first time, a maximum superconducting transition temperature of 288 K was observed: about 15 degrees Celsius or 59 degrees Fahrenheit. A simple refrigerator or heat pump would suddenly make superconductivity possible.

Inside a material subjected to a changing external magnetic field, small electric currents known as … [+] eddy currents will develop. Normally, these eddy currents decay away rapidly. But if the material is superconducting, there is no resistance, and they will persist indefinitely.

Cedrat Technologies

Last year’s discovery represented a tremendous symbolic breakthrough, as the increase in known superconducting temperatures followed a steady progression in recent years under extreme pressures. The 2015 work in pressurizing hydrogen and sulfur cracked the 200 K barrier, and 2018 research in a high-pressure compound involving lanthanum and hydrogen cracked the 250 K barrier. The discovery of a compound that can superconduct at liquid water temperatures (albeit at extremely high pressures) isn’t exactly a surprise, but it is a really big deal to break the room temperature barrier.

However, it seems that practical applications remain significantly far off. Achieving superconductivity at mundane temperatures but extreme pressures is not significantly more accessible than achieving it at mundane pressures but extreme temperatures; both are barriers to widespread adoption. In addition, the superconducting material only persists as long as the extreme pressures are maintained; once the pressure drops, so does the temperature at which superconductivity occurs. The next big step — one that remains to be taken — is to create a room temperature superconductor without these extreme pressures.

This is an image, taken with scanning SQUID microscopy, of a very thin (200 nanometers) … [+] Yttrium-Barium-Copper-Oxide film subjected to liquid helium temperatures (4 K) and a significant magnetic field. The black spots are vortices created by the eddy currents around the impurities, while the blue/white regions are where all the magnetic flux has been expelled.

F. S. Wells et al., 2015, Scientific Reports volume 5, Article number: 8677

The concern is that there may be some sort of a Catch-22 situation at play here. The highest-temperature superconductors at standard pressures don’t appreciably change in behavior as you vary the pressure, while the ones that superconduct at even higher temperatures under high pressures no longer do so when you reduce the pressure. Solid materials that are good for making wires out of, like the various copper oxides discussed earlier, are very different than the pressurized compounds that are only created in trace quantities under these extreme laboratory conditions.

But — as first reported by Emily Conover at Science News — it’s possible that theoretical work, aided by computational calculations, could help point the way. Each possible combination of materials can give rise to a unique set of structures, and this theoretical and computational search can help identify which structures may be promising for obtaining the desired properties of high-temperature but also lower-pressure superconductors. The 2018 advance that crossed the ~250 K superconducting barrier for the first time, for example, was based on such calculations, which led to the lanthanum-hydrogen compounds that were then experimentally tested.

This diagram shows the structure of the first high-temperature low-pressure superhydride: LaBH8. The … [+] authors on this 2021 work were able to predict a hydride superconductor, LaBH8, with a high superconducting temperature of 126 K at a pressure down to 40 gigapascals: the lowest pressure ever for a high temperature superconducting hydride.

S. Di Cataldo et al., 2021, arXiv:2102.11227v2

Already, such calculations have pointed towards a substantial advance by leveraging a new set of compounds: yttrium and hydrogen, which superconduct at near-room temperatures (-11 Celsius, or 12 Fahrenheit) but at substantially lower pressures than were previously required. While metallic hydrogen — which only exists at ultra-high pressures, such as those found at the bottom of Jupiter’s atmosphere — is expected to be an excellent high-temperature superconductors, the addition of extra elements could lower the pressure requirements while still maintaining the high-temperature superconductivity property.

Theoretically, all single-element combinations with hydrogen have now been explored for superconductivity properties, and the hunt is now on for two-element combinations, such as the carbon-sulfur-hydrogen compound previously discovered experimentally by Dias. Lanthanum and boron with hydrogen has shown promise experimentally, but the number of possible two-element combinations rises into the thousands. Only with computational methods can we receive guidance on what we ought to try next.

Squeezed to high pressure between two diamonds, a material made of carbon, sulfur and hydrogen … [+] superconducts: transmitting electricity without resistance at room temperature. So long as the pressure and temperature simultaneously remain above a certain critical threshold, the resistance will remain at zero. This compound holds the record for highest superconducting temperature: 15 C (59 F).

J. Adam Fenster / University of Rochester

The biggest questions surrounding high-temperature superconductivity now all involve the pathway to getting to low pressures as well. The true “holy grail” moment will come when mundane conditions — in both temperature and pressure — can create a situation where superconductivity still persists, enabling a wide variety of electronic devices to leverage the power and promise of superconductors. Although individual technologies will advance, from computers to maglev devices to medical imaging and much more, perhaps the biggest benefits will come from the savings of vast amounts of energy in the electrical grid. High-temperature superconductivity, according to the US Department of Energy, could save the United States alone hundreds of billions of dollars in energy distribution costs annually.

In a world of finite energy resources, the elimination of any inefficiencies can benefit everyone: energy providers, distributors, and consumers at all levels. They can eliminate problems such as overheating, greatly reducing the risk of electrical fires. And they can also increase the lifespan of electronic devices while simultaneously reducing the need for heat dissipation. Once a novelty, superconductivity leapt into the scientific mainstream with the 20th century’s advances. Perhaps, if nature is kind, it will leap into the consumer mainstream with 21st century advances. Impressively, we’re already well on our way.

#News

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levysoft · 6 years ago

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Notizia bomba nel campo dell’informatica quantistica. Trapelata, poi ritirata, ma mai smentita né confermata ufficialmente. La scorsa settimana �� apparso su sito della Nasa un paper dal titolo Quantum supremacy using a programmable superconducting processor, ossia Supremazia quantistica usando un processore superconduttivo programmabile. L’articolo è rimasto online per poche ore (fortunatamente qualche anima pia ha provveduto a salvarlo) ma tanto è bastato a generare una valanga di commenti, controversie, polemiche, supposizioni e speranze tra la comunità degli addetti ai lavori. Questo il succo: Sycamore, il computer quantistico di Google, sarebbe riuscito a conseguire la cosiddetta supremazia quantistica, ossia a svolgere nel giro di pochi minuti, e per la prima volta al mondo, una serie di operazioni che i computer tradizionali impiegherebbero decine di migliaia di anni a svolgere. Abbiamo cercato di capire, con l’aiuto di un esperto, quanto c’è da fidarsi, perché si tratta di una notizia così importante e cosa potrebbe cambiare nel futuro qualora fosse confermata.

Recap: cos’è e come funziona un computer quantistico

Cominciamo dalle basi, anche per sgomberare il campo da ambiguità e incomprensioni. Un computer quantistico sfrutta alcune tra le proprietà più bizzarre e controintuitive della meccanica quantistica per ottenere una potenza di calcolo di gran lunga superiore rispetto a quella di un computer (e di un supercomputer) classico. Come tutti sanno, l’unità minima di informazione di un processore convenzionale è il bit, un’entità binaria che può assumere i valori zero e uno a seconda del passaggio o meno di corrente. Dal canto loro, i processori quantistici usano i qubit, in genere particelle subatomiche come fotoni o elettroni, che invece possono immagazzinare molte più informazioni: “I processori tradizionali”, racconta Tommaso Calarco, direttore del Jara-Institute Quantum Information e presiedente dello European Quantum Flagship Network, “ammettono solo due stati, lo zero e l’uno, legati al passaggio o al non-passaggio di corrente, cioè di un flusso di elettroni. Nei processori quantistici, invece, ogni singolo elettrone trasporta un’informazione, il che amplifica enormemente la potenza di calcolo”.

Le leggi della meccanica quantistica, infatti, postulano (tra le altre cose) che ogni particella sia soggetta al cosiddetto principio di sovrapposizione, ossia – per dirla rozzamente – si possa trovare contemporaneamente, con probabilità diverse, in più stati differenti. “Il principio di sovrapposizione consente di superare il dualismo acceso/spento e di veicolare molta più informazione: una particella quantistica può rappresentare contemporaneamente più stati”. Il qubit, insomma, permette di parallelizzare i calcoli, cioè di svolgere molte, moltissime operazioni contemporaneamente.

Non sostituirà i computer tradizionali, per ora

Attenzione: quanto detto finora, probabilmente, non vuol dire che nel prossimo futuro i processori classici andranno definitivamente in pensione. Per la maggior parte delle operazioni convenzionali saranno ancora l’opzione più efficienteed economica: usare un computer quantistico per il rendering di un video o per abbattere i mostri di un videogioco sarebbe come sparare a una mosca con un cannone. Diverso è il caso di settori come la scienza dei materiali, o l’industria farmaceutica, o la fisica delle particelle: in questi scenari un processore quantistico potrebbe davvero cambiare completamente – e per sempre – le regole del gioco, rendendo possibili avanzamenti tecnologici di vastissima portata e difficili da prevedere a priori.

A che punto siamo?

Questi mesi rappresentano una fase cruciale nella storia dello sviluppo dei computer quantistici. Appena pochi giorni prima del leak di Google, Ibm ha annunciato che a ottobre prossimo consentirà a ingegneri, fisici e informatici di accedere da remoto a un computer quantistico a 53 qubit, il più potente mai costruito dall’azienda e il maggiore mai messo a disposizione per uso esterno. La notizia è arrivata a coronamento di sforzi che vanno avanti da anni: nel 2017, come vi avevamo raccontato, gli scienziati di Ibm erano riusciti a simulare con successo un computer quantistico a 56 qubit all’interno di un processore tradizionale con 4.5 terabyte di memoria.

Dal canto suo, invece, Google ha a disposizione Sycamore, un computer a 54 qubit (uno dei quali sembra non funzionare come dovrebbe, e pertanto ne vengono utilizzati 53), e un altro sistema a 72 qubit, che al momento si è rivelato però troppo difficile da controllare. Tutto perché i sistemi quantistici sono estremamente delicati, e particolarmente suscettibili anche a impercettibili interferenze esterne (termiche ed elettromagnetiche, per esempio): “Per dare un’idea della difficoltà enorme di gestire e controllare i computer quantistici”, ci spiega ancora Calarco, “si può pensare ai qubitcome ai componenti di un’orchestra chiamata a suonare la nona sinfonia di Beethoven. Però ciascun musicista deve riuscire a farlo con guantoni da boxe alle mani e casco sulla testa. E in una stanza tenuta a novanta gradi di temperatura. È un compito veramente molto, molto difficile”.

Supremazia quantistica vs vantaggio quantistico

Veniamo a Google. Cosa vuol dire supremazia quantistica? “Di per sé, si tratta di un concetto molto semplice”, dice ancora Calarco. “Vuol dire riuscire a risolvere, con un computer quantistico, un calcolo che un computer tradizionale non riuscirebbe a risolvere, quantomeno in un tempo ragionevole”. Nella fattispecie, Sycamore è riuscita a dimostrare che una sequenza di numeri casuali è realmente casuale (un problema matematicamente molto complesso) in circa tre minuti e venti secondi; Summit, il supercomputer (tradizionale) più potente al mondo, ci impiegherebbe circa 10mila anni.

“Il problema risolto da Sycamore, in sé, è del tutto inutile, o meglio ha interesse puramente accademico. La sua importanza è legata al fatto che riuscire a risolverlo dimostra una volta per tutte che abbiamo conseguito la supremazia quantistica. È il coronamento di quello che pensavamo fosse solo un sogno, e che ora sappiamo in realtà essere fattibile”. Il prossimo passo, spiega ancora Calarco, sarà passare dalla supremazia quantistica al vantaggio quantistico, cioè all’effettiva progettazione di algoritmi da far svolgere ai computer quantistici del futuro. È come se in questo momento abbiamo mostrato che è possibile costruire una macchina velocissima, ma ci mancano ancora strade, distributori di benzina, infrastrutture. E soprattutto partenze e destinazioni. “È ancora decisamente troppo presto per immaginare tutte le applicazioni. Potrebbero essere davvero sterminate, e strabilianti. I prossimi passi sono anzitutto migliorare ulteriormente l’hardware, arrivando a controllare con precisione sistemi a 100 o più qubit, e poi lavorare allo sviluppo di algoritmi che permettano di arrivare al vantaggio quantistico”. Il futuro ci attende.

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