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July, 2019

The mystery of entanglement deepens

Pre-reading warning: this will make your head hurt, and if it doesn't, you probably misunderstood it. 🙂 HangZhou Night Net

One of the key mysteries of quantum mechanics is called entanglement. Imagine some crystal that (somehow) emits two photons via a single process: the state of the photons will be correlated. If you then manipulate the state of one photon: the state of the other photon will be instantaneously changed as well, independent of the distance separating them. Although entanglement cannot be used to transmit information, it is a critical part of quantum computers. For computing, we rely on the entanglement to make the state of one qubit depend intrinsically on the state of other qubits. However, entanglement is very delicate and this mysterious linkage between two particles can be easily destroyed by interactions with its surroundings.

Experimental research1 to be published in Science shows that entanglement can destroy itself even in the absence of environmental noise. I won't describe the actual experiment here, but essentially the researchers created entangled pairs of photons and subjected them to a controlled amount of noise. Afterwards, the state of the photons was measured to see how well entangled they were. What they discovered is that entanglement can just simply disappear, even when the amount of noise suggests that it should remain.

In physical systems, the probability per unit time of an event occurring—such as entanglement vanishing—is often constant. This means that a long tail is always present, which is often useful in many experiments and engineering systems, because it means you have a known amount of time in which things can be done. Apparently, entanglement does not always disappear gracefully, but rather stomps off in a huff before the party is half over.

Additionally, the researchers noted that different entangled states evolve very differently. They show data where the entanglement between two states decays gracefully, while for others it disappears very quickly, despite the starting states being very similar.

These two findings have serious implications for quantum encryption and quantum computing, both of which rely on entanglement. For these applications to advance, stable and long lasting entanglement is required. Being able to choose the system so that only certain entangled states are produced will probably turn out to be quite challenging.

1 First author: M. P. Almeida

Climate: Life in the twilight zone

In the coming issue of Science, there is a piece of research that contributes to our understanding of the climate. HangZhou Night Net

The paper1 deals with how the ocean can act as a carbon store and how big that store might be. The ocean interacts with carbon in three basic ways. First, there is carbon dioxide that is dissolved in the water. This carbon is in equilibrium with the surrounding atmosphere, and the water cannot be thought of as a storage room for carbon. The second is in ocean life, which is carbon based. However, when organisms die, they enter into a complex cycle that ultimately leads to part of the carbon being recycled into the atmosphere and some being stored on the ocean floor. In this way, life in the ocean is not itself considered a carbon store, but rather a stepping stone on the way to storing carbon. The question is, of course, how much carbon makes it out of the ocean life cycle to end up on the sea floor?

The amount of carbon recaptured by ocean life as the dead organisms sink to the ocean floor has, up to now, been modeled as an exponential decay. The decay starts at the ocean surface and continues through the twilight zone, where ocean life is still abundant. After the twilight zone, no significant capture is considered to take place so the particulates reach the ocean floor and remain there. It is pretty clear that this is simply an "on average" model, which simply cannot take into account local conditions. The research in the linked paper reports on the variability of carbon storage between geographic locations. To do this, the researchers designed novel neutral buoyancy traps. These traps stay at a predetermined depth for a predetermined time, and catch particles as they fall. The traps are only open while at depth, so it is a true measure of the density of particulates falling towards the ocean floor at that depth. These traps were set in cold water, near the Arctic circle, and in warm water, near Hawaii, at multiple depths, and the measurements were repeated (a very expensive exercise for ship-based experiments).

They discovered that the simple model underestimates the ability of life to keep carbon in circulation. Using the measured temperature differences, the model estimates are approximately 11 petagrams per year (1 petagram = 1×1015 grams), while the actual collected particles indicate only 2.3-5.5 petagrams per year—a short fall of around 1 year of anthropogenic carbon. Although both sites showed a substantial amount of variability (20-50 percent), the measured variability is not enough to make up the short-fall.

What is of more concern is the observed temperature dependence, which shows increasingly poor carbon storage as the temperature increases—a positive feedback loop. Moreover, this will be likely to couple with other expected effects, such as an increase in stratification and increasing acidity.

In related news, the Guardian has summarized Mark Lynas' book called 6 Degrees. Lynas has gone through scientific literature of the past decade or so to compile a sort of compendium on what we can expect for each degree increase in temperature. It is intentionally scary—as it should be—and makes it clear that everyone will be affected by even a fairly small 1 degree Celsius increase in global average temperature.

1 First author: K. O. Buesseler

Rift-to-drift transition triggered catastrophic global warming

The Paleocene-Eocene thermal maximum (PETM) was a global disruption: mean temperatures rose 5-6° C as over 1,500 Gigatons of carbon entered the atmosphere. That carbon acidified the oceans, causing a major extinction of sea life. Both temperatures and carbon levels remained high for hundreds of thousands of years. But new data that will appear in the next issue of Science suggests the global disruption had a local cause: the break up of plates that produced the North Atlantic. HangZhou Night Net

The PETM occurred roughly 55 million years ago, and the timing suggested a possible link, as the split between Europe and Greenland occurred at roughly that time. These geological events are often accompanied by major volcanic activity, which will also tend to pump a lot of carbon into the atmosphere. But the evidence for volcanic activity at the time of the PETM is sparse, and the biggest volcanic event near that time occurred approximately 450,000 years after the PETM.

The new work focused on the ash from this later event (called Ash-17, and found in Denmark). The authors were able to show that ash from sites in Greenland dated from precisely the same period, and shared chemical properties with Ash-17, suggesting they were formed in the same event. Using this information, they then tracked the Greenland geologic column backwards in time towards the PETM.

They found that the time of the PETM marked a major transition in Greenland geology: the first appearance of rocks that bear the signature of having formed at a mid-ocean ridge. They also looked at data from the other side of the break up in the Faeroes Islands, and found that they showed an identical timing of the appearance of rock formed at a ridge. Thus, the data suggests that the PETM doesn't correspond with a major eruption, but rather with the onset of a new phase in tectonic activity. This "rift to drift" transition marked the point where the breakup of Greenland and Northern Europe was complete, and regular spreading at the Mid-Atlantic Ridge began.

If a major eruption didn't occur, how did all the carbon get there? The authors say that their data favor a previously proposed model in which the Mid-Atlantic ridge formed under a sediment-rich ocean basin. The sudden influx of magma and heat disrupted the sediment, and released the huge amount of stored carbon left there by millennia of ocean life. Once it hit the atmosphere, global temperatures spiked.

We come not to bury Kutaragi, but to praise him

Sony has dominated video game consoles since the launch of the first PlayStation in the mid-90s, and the company has long been known for top-quality consumer electronics. In the past few years, Sony has seen their electronics market share diminish due to the lower prices of competitors like Samsung and Toshiba, and their fortunes didn't improve with the release of their expensive and much-hyped PlayStation 3 to lukewarm reviews and diminishing sales. HangZhou Night Net

Sir Howard Stringer has been attempting to improve the fortunes of the company, and the stock is once again rising. In thisperiod of change we now learn that the head of SCEI and the "father of the PlayStation" Ken Kutaragi is stepping down. While theexact reason for the change is unknown, Sony's game's division has suffered heavy losses in recent quarters and there have been widespread reports of Kutaragi's inability to work with other Sony executivesfor positive change.

Theeasy jokes about "Crazy Ken's" notable quotes shouldn't take away the long list of accomplishments that Ken Kutaragi has enjoyed since joining Sony directly aftergraduating from the University of Electro-Communications in Tokyo. After seeing the promise of big profits in video games with the rise of the Famicom, he pushed for Sony's inclusion in the Super Famicom system via Sony's SPC700 sound chip.

His reputation as a maverick iswell-earned. After Nintendo snubbed Sony while they were working on a CD-ROM add-on for the Super Famicom, the betrayal caused Sony to launch their own system: the PlayStation. The disc-based system took off and cemented Sony's place in gaming history after the Sega Saturn failed to sell in high numbers and the Nintendo 64 was hampered by its cartridge-based technology. With the launch of the PlayStation 2, Sony stood high above their competitors with full backwards compatibilityfor the original PlayStation and what was (at the time) an inexpensive DVD player. Sony Computer Entertainment became one of the company's biggest profit centers, and Kutaragi enjoyed the ride with a solid vision and some memorably wacky quotes.

Hecontinued to build hisreputation up until the launch of the PlayStation 3, claiming that the system would allow you to visit a "4D" world and that people will want to work harder to afford one. He also claimed that the system shouldn't be looked at as a games console. The inclusion of the Blu-ray drivedrove up the price and so far hasn't proved as strong of a sales motivator as the PlayStation 2's DVD drive.

Nintendo also proved to be a stronger competitor than Sony expected; the dominance of the Nintendo DS is a major obstacleto Sony's own portable, the PSP. The market has changed since the rise of Ken Kutaragi, and Sony now has to catch up. After a shaky US launch and before the European release, he was famously quoted admitting that Sony was losing their foothold in the market. "If you asked me if Sony's strength in hardware was in decline, right now I guess I would have to say that might be true," he said in an uncharacteristically candid moment.

Ken Kutaragi will be replaced by Kazuo Hirai, but will continue to work as a senior technology adviser for Sony. A shakeup in the command structure behind thePS3 may have a positive effect on future sales and strategy, turning thestruggling platform into a profitable business. Let's take this moment to thank Ken Kutaragi for his many innovative ideas and enthusiastic spirit in the world of gaming. Remember him every time you notice how great the Super Nintendo sounds, or how the PlayStation 2 led to the wider appeal of DVDs. We're looking forward to seeing his future projects.

Project Honey Pot springs $1 billion lawsuit on spammers

A "John Doe" lawsuit filed in the U.S. District Court in Alexandria, Virginia, this morning could be one of the largest anti-spam suits ever filed in the US so far. The suit was filed by Project Honey Pot, a free anti-spam service that collects information on e-mail address harvesters across thousands of sites on the Internet that have their software installed. The class-action complaint was filed on behalf of roughly 20,000 Internet users in more than 100 countries, according to the organization's web site. HangZhou Night Net

Because of webmasters large and small installing its software on their servers, Project Honey Pot has collected information on thousands of e-mail harvesters in the US—people or bots that automatically scan web sites for e-mail addresses and then store them in a database for sale to a spammer. The organization hopes that by filing the "John Doe" suit, they can use that information in conjunction with subpoenas to find out who the actual spammers are.

The lead attorney in the case is Jon Praed of the Internet Law Group. Praed has achieved quite the reputation as a "spam hunter" in recent years, as he has successfully represented AOL and Verizon against spammers.

Under Virginia's anti-spam statute and the federal CAN-SPAM law, Project Honey Pot's case could result in more than $1 billion in statutory damages against spammers. Although CAN-SPAM has been around since early 2004, the inability of lawmakers to find or identify the spammers in question has led to an increase in spam over the years instead of a decrease. However, Project Honey Pot's approach could actually yield some results, founder of myNetWatchman Lawrence Baldwin told the Washington Post. "If they're successful, I think it will yield some very usable information in terms of identifying who the real miscreants are. Let's just hope some of them are here in United States and therefore reachable," he said.

Project Honey Pot appears to be fully committed to the fight for its users, and although they acknowledge that spam won't go away even if the case succeeds, they hope that the case will help scare spammers in the future. The organization even says that should it win, it may give back to its community: "Since we will know what Project Honey Pot members provided the data that ends up winning the case, maybe we'll be able to send them a little bonus," wrote the company.