Here’s How Darpa’s Robot Ship Will Hunt Silent Subs

Here’s How Darpa’s Robot Ship Will Hunt Silent Subs

WIRED / Danger Room
By Spencer Ackerman
December 27, 2012


DARPA's former headquarters in the Virginia Square neighborhood of Arlington. This agency recently moved to 675 North Randolph Street, near the Ballston Common Mall.
DARPA’s former headquarters in the Virginia Square neighborhood of Arlington. This agency recently moved to 675 North Randolph Street, near the Ballston Common Mall.


Submariners like to say there are two kinds of ships: subs and targets. The Pentagon’s futurists want to turn that aphorism on its head, and develop a new kind of surface ship that can turn a sub into a target. Naturally, the sub-hunter won’t have a human on board. Here’s how it’s going to work.

The video above is a new promotional piece of machinima (do people still say that?) released by the defense contractor Science Applications International Corporation, which has a $58 million contract with Darpa to build its unmanned sub-hunter of the future. That maritime robot, called the Anti-Submarine Warfare Continuous Trail Unmanned Vehicle, or ACTUV, doesn’t exist yet and won’t for years. But here SAIC at least sketches out how the long, thin and “radically different” ACTUV can keep surface ships from becoming targets.


The really interesting thing here is how different the surface-gliding ACTUV is from the now-familiar drones that litter the skies. Even the longest-flying drones can only stay in the air for 30 hours or so. SAIC intends for this thing to stay on a hunt for 60 to 90 days.

What’s more, SAIC is designing the ACTUV to be way more autonomous than contemporary drone aircraft: After a sailor powers it up and helps guide it out of port, she can go on a long vacation while the ACTUV speeds out to the open water to use its long-range acquisition sonar and other advanced sensors to scan for submarines, while automatically steering clear of any nearby surface ships.

Assuming SAIC isn’t over-promising (much), the sonar pods underneath the belly of the ACTUV create an acoustic image of a submarine and pursue it at high speed — although that’s something that can only happen when the ACTUV gets fairly close to its quarry. (More on that in a second.) Once the ACTUV thinks it’s got something, it pings nearby Navy ships through a satellite link. If a sailor thinks the ACTUV has made a mistake, he can convey that back to the unmanned ship and it’ll move on.

If not, the ACTUV operates alongside the fleet, with coordination not often seen with aerial drone tactics. SAIC apparently wants the ACTUV in constant communication with a mothership and Naval aircraft that would fly overhead and drop sonar charges to hunt the mystery sub, with the ACTUV speeding along to keep pace with the swift submarine. SAIC seems to intend for the ACTUV to follow the sub back to its home port (!) if necessary, or until a human in the fleet commands it to break contact. The ACTUV, in case you were wondering, isn’t armed.

How all this will happen isn’t yet clear. The subs that really give the U.S. Navy pause are cheap diesel-electric models, which are technologically puny compared to the Navy’s nuclear-powered subs but can be much quieter and harder to track. Russia sells them; Iran claims to have them. SAIC’s video suggests that the ACTUV can’t actually find the diesel-electric sub on its own: The scenario here depends on a Navy commander suspecting there’s an enemy sub in the area and deploying a P8 Poseidon surveillance aircraft (successor to the P-3C Orion) to drop sonar buoys to find it. The ACTUV sprints out in a certain pattern while “predict[ing] that long-range sensors will be able to completely envelop” the area where the sub might be “and prevent successful evasion.” So not an exact science, but its sonars are said to get more precise the closer the ACTUV gets to the suspected sub target.

The on-board hardware described generically in the video relies on “collected data and sophisticated logics” to “infer the intent” of watercraft. So that should at least make the ACTUV cognizant of any sizable metal thing that seems to be tracking a Navy ship. And if SAIC is right that the ACTUV can really hear the diesel-electric subs, then that enemy sub really may become the ocean’s newest target.

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How One Myst Fan Made Himself a Real-Life Linking Book


How One Myst Fan Made Himself a Real-Life Linking Book

by Tim Maly
November 24, 2012

Mike Ando’s Myst Book
Mike Ando’s Myst Book


The classic PC game Myst was known for drawing people in to its massive, surreal world. But maker Mike Ando took a little piece of that world and drew it into ours. He made a lovingly authentic replica of the Linking Book that helps the main character — you — navigate the world.

Myst was a ground-breaking point-and-click adventure game created by Cyan Worlds, made of hundreds of beautifully rendered scenes whose combined size made the game so big that it needed a CD-ROM to play, back when many computers didn’t have them. It was the first breakout hit in PC gaming and from its release in 1993 it held the title of best-selling PC game until 2002 when The Sims surpassed it.

The game spawned four sequels, along with novels, music, and an MMO that is still online and being powered by donations from the fan base. The games have been widely ported and the game — once so huge that you needed special hardware to run it — is now available for download on iOS (among other places). In other words, it’s a pretty big deal.


At the core of Myst’s story was a mystical technology called Linking Books that pulled players into other realms, called Ages. They were these beautiful old tomes that, when opened, showed an animated preview of the Age to which you’d be linked.

“Ever since I first played the game, I always wanted my own linking book,” says Ando, “Of course, there was no way my old bulky 486 would fit within a book, but as time marched on technology advanced and computers became smaller. Eventually technology caught up and it was possible to shrink everything down to fit inside the book.”

Ando says his drive to make this project began six years ago when he learned where Cyan got the texture reference for the books — Harper’s New Monthly Magazine, Volume LIV, Issue 312, December 1876 to May 1877. “My mind hatched all sorts of plans about what I’d do once I had the book,” he says, “and finally I decided to set the bar as high as I could — all the Myst games, all playable, and playable well, even the 3-D ones at 30fps.”

To do this, Ando needed to perform two main feats. First, he needed to find the parts to make a computer that would fit in an extremely limited space. Then, he needed to restore the antique book, customize it to look like the ones from Myst, and gut it to make room for the compact computer that would power the game.

Ando’s Myst Book interior. “There was more than one time when I would’ve done anything for an extra 2 millimeters,” he says.
Ando’s Myst Book interior. “There was more than one time when I would’ve done anything for an extra 2 millimeters,” he says.


“Research was the main skill involved,” says Ando, “I spent hundreds of hours, literally, trying to find suitable components to meet all my requirements.”

To build the tiny computer that powers the Linking Book, Ando needed to find a X86 board that could fit inside. Most mobile devices run on ARM, but Ando wanted to run the original releases of each game, so porting wouldn’t do. It had to be X86.

“To give you an idea of how uncommon it is to shrink an X86 computer down this small,” he says, “the smallest X86 computer made by Apple, the Mac Mini, is 17 cm — this book is only 12 cm, plus I had to squeeze in my own power source and screen.”

The parts that made up the computer came from specialist vendors that ordinarily sell to aerospace and other niche enterprise customers. Ando ended up ordering a mixture of store-bought parts, and custom PCB layouts, soldering the whole thing together and switching out components between a bunch of boards to get the most efficient versions. He says he designed the touchscreen controller himself.

And as for the touchscreen itself? At one point in his search, he found himself talking to a vendor in China to arrange for a custom design. “His English skills were so poor I suggested we talk in Chinese and I used Google Translate, so I guess you could add that to my skills,” he says. “I suspect he just found one already to size and charged me as if they made it. If so, good for him — I couldn’t find one anywhere.”

The Myst Book’s exterior. Book Restorer Ian Bates “worked wonders with the book’s exterior, especially given how fragile the book was. (It’s made from essentially 135-year-old newspaper stock that tears incredibly easily and doesn’t like to cut straight),” says Ando.
The Myst Book’s exterior. Book Restorer Ian Bates “worked wonders with the book’s exterior, especially given how fragile the book was. (It’s made from essentially 135-year-old newspaper stock that tears incredibly easily and doesn’t like to cut straight),” says Ando.


For restoration and preparation of the book, Ando turned to Ian Bates, the president of the Australian Bookbinding Association. Bates handled the restoration of the cover, along with cutting the pages and embossing the book with the Myst logotype (but only after Ando had picked which of the several versions of the Myst font they should use).

If you find yourself gasping in horror at the idea that a book restorer would destroy a beautiful old book for a strange electronics project, Ando wants to assure you that nothing of value was lost. “The book I used is basically a cross between a Reader’s Digest & a gossip magazine and many of the articles are incomplete,” he says, “Today, books like this are sold to interior designers literally by the meter without any care given to their contents, author or title. Their main value rests on the aesthetics of their spine.”

Photos courtesy of Mike Ando.
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Tragedy as woman with debilitating sexual arousal disorder that made her orgasm up to 50 times in a row commits suicide


Tragedy as woman with debilitating sexual arousal disorder that made her orgasm up to 50 times in a row commits suicide

  • Gretchen Molannen, 39, suffered from persistent genital arousal for 16 years
  • She committed suicide a day after paper published her story
  • Condition meant it was impossible to work
  • Turned down for disability twice
  • Appealed on Craigslist for a free MRI scan so she could prove condition to judge
  • Attempted suicide three times in the last year

Daily Mail (UK)
By Rachel Quigley and Beth Stebner
December 4, 2012

A woman who suffered from a debilitating condition where she had constant, uncontrollable orgasms has committed suicide after years of battling her affliction.

Gretchen Molannen, 39, was found dead in her home in Spring Hill, Florida, over the weekend from an apparent suicide. 

She had suffered from persistent genital arousal disorder (PGAD) for more than a decade-and-a-half.

The condition means the afflicted are physically but not psychologically aroused and can often only find relief after masturbating for hours upon end.

Desperate: Gretchen Molannen, 39, was found dead in her home in Spring Hill, Florida, over the weekend from an apparent suicide. She had suffered from persistent genital arousal disorder (PGAD) for more than a decade-and-a-half
Desperate: Gretchen Molannen, 39, was found dead in her home in Spring Hill, Florida, over the weekend from an apparent suicide. She had suffered from persistent genital arousal disorder (PGAD) for more than a decade-and-a-half


Trauma: The condition means the afflicted are physically but not psychologically aroused and can often only find relief after masturbating for hours upon end
Trauma: The condition means the afflicted are physically but not psychologically aroused and can often only find relief after masturbating for hours upon end


It is unclear how or when the 39-year-old died. The Hernando County Sheriff’s office responded to a suicide call on Saturday night and two of her friends confirmed it.

The Tampa Bay Times had done a profile on Ms Molannen only a week before, speaking to her about her debilitating disorder.

‘I had such a different life before this thing, this beast, took over,’ she said in November. Ms Molannen explained that she began feeling the sensation when she was 23, describing that it was like a switch she couldn’t turn off.

‘I used to love life. But this has destroyed it. This isn’t living. What’s the point? I think about suicide all the time,’ she said.

One of the only forms of relief came from masturbating for hours on end, something that Ms Molannen, a Lutheran, found as a point of shame.

Though she had aspirations of working as a translator as she is fluent in French, German and Spanish, her condition meant that she had to take odd jobs, because she had to deal with the physical demands of PGAD.

But, having to relieve herself almost constantly, she stopped working in 1999 and started spending most of the time in her bedroom with her vibrator.

Agony: Gretchen Molannen
Agony: Gretchen Molannen


‘I was terrified,’ she said. ‘I couldn’t get unaroused. I didn’t know what to do.’

Her distress over the condition made her attempt suicide three times in the past year.

‘I know that God wants more out of my life than having me testing out suicide methods, constantly crying and abusing myself,’ she said.

Agony: Gretchen Molannen, 39, pictured on her Facebook page wearing a mask, committed suicide on December 1 because of a debilitating condition which caused her to have repeated, uncontrollable orgasms
Agony: Gretchen Molannen, 39, pictured on her Facebook page wearing a mask, committed suicide on December 1 because of a debilitating condition which caused her to have repeated, uncontrollable orgasms


She tragically revealed to the paper she had been molested for years by a neighbor, who said she was being punished for being bad. She wondered if that had anything to do with it?



Persistent genital arousal disorder is a fairly recent phenomenon, first described in medical literature in 2001.

Sufferers describe symptoms as only physical arousal. Women who have the disorder say that they experience symptoms that are intense and incredibly uncomfortable.

Some women may temporarily lesson the symptoms by masturbating and reaching orgasm, though it is an ephemeral relief system. Treatment ranges from psychotherapy to various medications.

Doctors don’t agree what causes it but do agree on how debilitating it is.

Women have described getting it after falling over, childbirth, menopause and coming off anti-depressants.



She had a boyfriend, who emailed the Times after her original story was published, saying the article ‘won’t help her now’ because she had killed herself.

They had sex around four times a year, the Times said, because it caused Ms Molannen hours of agony afterward. She agreed to it in a bid for physical intimacy. 

Unable to hold down any full-time employment. Ms Molannen said she tried to file for disability twice, and was twice denied. 

Because of this, the boyfriend had paid her taxes so she could keep her parents’ house.

Her worst day, she said, was when she had 50 uncontrolled orgasms in a row.

‘It made me think I was going to die,’ she told the newspaper. ‘That was the worst day.’

Describing the first time she felt it, Ms Molannen said she thought it was just a hormonal change women went through that they didn’t talk about, so she suffered in silence for ten years.

‘I noticed something wasn’t right any more but thought maybe I’ll grow out of it. So I waited and waited – its been almost 16 years and I’m still waiting.’

Describing the orgasms she experiences, she said: ‘All the feelings that people have when they are aroused, they’re there. The genital congestion, throbbing pulsating, heart pounding, it’s all there but the difference is tremendous anxiety – anxiety which is devastating and traumatizing. 

‘I try to tell myself it’s not real and just ignore it. Sometimes I can resist it and sometimes I just can’t.’

Breaking down in tears she told the Times: ‘I had no idea other people were going through this

‘I wish I could have told my mom, and even my dad about it. I wish I could have told my parents’ friends I wasn’t in my room wasting my life away.’

The paper found her after she posted an ad on Craigslist seeking help at the beginning of the year. She wanted someone to give her a free MRI scan so she could prove her condition to a judge.

Tragically, after the story was published – and after she had committed suicide – a number of people reached out to the paper to offer their help.

According to the Journal of Sex and Marriage Therapy, any number of events or medications can trigger the disorder, including going off antidepressants, starting menopause, and even a bad fall.

It is unclear how many women suffer from the disease, but experts estimate it to be in the thousands.


‘The arousal won’t let up. It will not subside. It will not relent. One O-R-G will lead you directly into the horrible intense urge, like you’re already next to having another one. So you just have to keep going.

‘I mean, on my worst night I had 50 in a row. I can’t even stop to get a drink of water. And you’re in so much pain. You’re soaking in sweat. Every inch of your body hurts. Your heart is pounding so hard.

‘You have to ignore it, Gretchen. YOU DON’T HAVE A CHOICE. STOP NOW. Just let your body calm down. Many times, I’ve tried that.

‘I’d be as far as in the bathroom, going in for my reward shower. I’m done. Now it’s time to clean up and relax. And I’d look at myself in the mirror and there it is again. And I’d throw myself on the floor and cry.

‘Men don’t understand it. They don’t care. They think it’s hot…When I describe it to men, I tell them, “Imagine having an erection that does not go down, that feeling of just before it comes out, all day, all night, no matter how many times, no matter how much you’ve destroyed the skin on your penis”.

‘It won’t let you calm down. You can’t go to sleep. You think you are going to have a heart attack. You think you are going to die.’

Source: Tampa Bay Times

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OBAMA POLITICAL AGENDA: Gun-control issue hits boiling point… President pledges to act


Gun-control issue hits boiling point

President pledges to act

The Washington Times
By David Sherfinski
December 16, 2012



Another Obama Political Exploit
Another Obama Political Exploit


President Obama on Sunday night pledged the remainder of his presidency to taking steps to end the string of spree shootings that have scarred the nation’s consciousness in recent years.

Addressing both the grief-stricken Newtown, Conn., residents packed into a crowded high school auditorium and an outraged nation watching the televised speech at home, the president said tragedies like the shooting that claimed the lives of 20 children and six adults inside Sandy Hook Elementary must end.

“I’ll use whatever power this office holds to engage my fellow citizens,” the president said, “in an effort aimed at preventing more tragedies like this. Because, what choice do we have?

“Are we really prepared to say that we’re powerless in the face of such carnage?” he said. “That the politics are too hard? Are we prepared to say that such violence visited upon our children year after year is simply the price of our freedom?”

The president stopped short of describing specific legislation, but new gun-control measures are already coming together on Capitol Hill, where Democrats are promising action in the wake of the Friday massacre in Newtown, in which a 20-year-old man armed with three semiautomatic weapons broke into a school and executed two classrooms full of children and the adults who tried to protect them.

Sen. Dianne Feinstein said Sunday that she would introduce a bill to reinstate the federal ban on assault weapons on the first day of the next Congress in January as gun-control advocates pressure Mr. Obama to tackle the issue in the wake of the school massacre Friday.

The shooting deaths could force the president to tackle an issue that was largely on the sidelines during his first term in office as he dealt with an anemic economy, perpetual overseas tumult and a bruising battle to push his health care overhaul through Congress.

“It will ban the sale, the transfer, the importation and the possession, not retroactively, but prospectively,” Mrs. Feinstein, California Democrat, said of her bill on NBC’s “Meet the Press.” “We exempt over 900 specific weapons that will not fall under the bill. But the purpose of this bill is to get … weapons of war off the streets.

“I think America is ready,” she said, adding that she thinks Mr. Obama will support the bill.

** VIDEO:  Gun-control issue hits boiling point

The president said in his weekly address Saturday that “we have to come together and take meaningful action to prevent more tragedies like this. Regardless of the politics.”

Rep. Jerrold Nadler, New York Democrat and a staunch gun-control advocate, said if now isn’t the time to have a serious discussion about gun control, he doesn’t know when that time is.

“How many more Columbines and Newtowns must we live through?” he said. “I am challenging President Obama, the Congress and the American public to act on our outrage and, finally, do something about this.”

Sen. Joe Lieberman, Connecticut independent, and Sen. Richard J. Durbin, Illinois Democrat, said on “Fox News Sunday” that they support reinstating the federal ban on assault weapons, which took effect in 1994 and lapsed in 2004. Other Connecticut Democrats, such as Sen. Richard Blumenthal and Sen.-elect Christopher S. Murphy, said action must be taken soon, but they were focused on the victims’ families in the immediate future.

Gun-control advocacy groups are pushing Mr. Obama hard to pursue specific policy.

Ladd Everitt, a spokesman for the Coalition to Stop Gun Violence, said Sunday that the group is “tremendously disturbed” by the incident and “our feeling is that we never should have allowed our country to reach this point.”

He said the reaction to this massacre is markedly different from what he saw after mass shootings in Columbine, Colo., and Virginia Tech; the attack on Rep. Gabrielle Giffords in Arizona; and the recent killings in Aurora, Colo.

“The response to those shootings was significant, but I have never seen the outrage to what we’ve seen in the past 48 hours,” he said. “The tone of the commentary has shifted from ‘Do we do something?’ to ‘What do we do?’ The will is there right now.”

Mayors Against Illegal Guns, the group co-chaired by New York Mayor Michael R. Bloomberg, has launched an online petition to “demand a plan” from Mr. Obama and Congress to end gun violence.

Mr. Bloomberg said on NBC’s “Meet the Press” that the issue should be Mr. Obama’s “No. 1 agenda.”

“He’s the president of the United States, and if he does nothing during his second term, something like 48,000 Americans will be killed with illegal guns,” Mr. Bloomberg said. “That is roughly the number of Americans killed in the whole Vietnam War.”

A petition on the White House website to “immediately address the issue of gun control through the introduction of legislation in Congress” has received more than 120,000 signatures since Friday. The White House must respond within 30 days to petitions that acquire at least 25,000 signatures.

Rep. Cathy McMorris Rogers, Washington Republican and chairwoman of the House Republican Conference, cautioned against introducing legislation immediately.

“We need to find out what happened and what drove this individual to this place,” she said. “I think we have to be careful about new, suggesting new gun laws. We need to look at what drives a crazy person to do these kinds of actions and make sure that we’re enforcing the laws that are currently on the books. And yes, definitely, we need to do everything possible to make sure that something like this never happens again.”

The country’s response to the Sandy Hook shootings was a topic in pulpits across the country on Sunday.

Speaking to worshippers at the Washington National Cathedral, the Very Rev. Gary R. Hall announced that “enough is enough” and that it was time for the church to take up the gun-control issue and not put it down.

“What does it say about us as a society that we continue to tolerate so much violence against children?” Mr. Hall said. “To my way of thinking, the best way for us to mourn the Sandy Hook shooting is to mobilize the faith community for gun control. … Today we grieve, but soon we act.”

Gun rights advocates say the violence might have been mitigated if people in the school had been armed.

Rep. Louie Gohmert, Texas Republican, said he wished Dawn Hochsprung, the principal of Sandy Hook, who was shot as she ran and attempted to overpower gunman Adam Lanza, had access to a rifle during the shooting spree Friday.

“Hearing the heroic stories of the principal, lunging, trying to protect. … I wish to God she had had an M-4 [carbine rifle] in her office locked up so when she heard gunfire, she pulls it out, and she didn’t have to lunge heroically with nothing in her hands, but she takes him out, takes his head off before he kills those precious kids,” Mr. Gohmert said on “Fox News Sunday.”

Philip Van Cleave, president of the pro-gun Virginia Citizens Defense League, said that moves to take away assault weapons wouldn’t stop events like the one in Connecticut.

“[If] evil wants to strike, it’s going to strike,” he said. “Everybody in that school was disarmed — that’s gun control. And once [Lanza] started, there was no way to stop him. And the police didn’t get there in time for all those children and adults.”

The National Rifle Association, meanwhile, has gone largely silent. The last entry on the organization’s Twitter feed was at 9:36 a.m. Friday, boasting “10 Days of NRA Giveaways — Enter today for a chance to win an auto emergency tool!”

On Dec. 13, a tweet proclaimed that the group’s Facebook page had reached 1.7 million “likes,” but the page disappeared from the online social-networking site. A spokeswoman for the group said in an email that “until the facts are thoroughly known, NRA will not have any comment.”

Jerry Seper contributed to this report.

Researchers Make Quantum Processor Capable of Factoring a Composite Number Into Prime Factors

Researchers Make Quantum Processor Capable of Factoring a Composite Number Into Prime Factors

Science Daily
August 19, 2012

Researchers Make Quantum Processor Capable of Factoring a Composite Number Into Prime Factors
The device in the photomicrograph was used to run the first solid-state demonstration of Shor’s algorithm. It is made up of four phase qubits and five superconducting resonators, for a total of nine engineered quantum elements. The quantum processor measures one-quarter inch square. (Credit: UCSB)

Computing prime factors may sound like an elementary math problem, but try it with a large number, say one that contains more than 600 digits, and the task becomes enormously challenging and impossibly time-consuming. Now, a group of researchers at UC Santa Barbara has designed and fabricated a quantum processor capable of factoring a composite number — in this case the number 15 — into its constituent prime factors, 3 and 5.

Although modest compared to a 600-digit number, the achievement represents a milestone on the road map to building a quantum computer capable of factoring much larger numbers, with significant implications for cryptography and cybersecurity. The results are published in the advance online issue of the journal Nature Physics.

“Fifteen is a small number, but what’s important is we’ve shown that we can run a version of Peter Shor’s prime factoring algorithm on a solid state quantum processor. This is really exciting and has never been done before,” said Erik Lucero, the paper’s lead author. Now a postdoctoral researcher in experimental quantum computing at IBM, Lucero was a doctoral student in physics at UCSB when the research was conducted and the paper was written.

“What is important is that the concepts used in factoring this small number remain the same when factoring much larger numbers,” said Andrew Cleland, a professor of physics at UCSB and a collaborator on the experiment. “We just need to scale up the size of this processor to something much larger. This won’t be easy, but the path forward is clear.”

Practical applications motivated the research, according to Lucero, who explained that factoring very large numbers is at the heart of cybersecurity protocols, such as the most common form of encoding, known as RSA encryption. “Anytime you send a secure transmission — like your credit card information — you are relying on security that is based on the fact that it’s really hard to find the prime factors of large numbers,” he said. Using a classical computer and the best-known classical algorithm, factoring something like RSA Laboratory’s largest published number — which contains over 600 decimal digits — would take longer than the age of the universe, he continued.

A quantum computer could reduce this wait time to a few tens of minutes. “A quantum computer can solve this problem faster than a classical computer by about 15 orders of magnitude,” said Lucero. “This has widespread effect. A quantum computer will be a game changer in a lot of ways, and certainly with respect to computer security.”

So, if quantum computing makes RSA encryption no longer secure, what will replace it? The answer, Lucero said, is quantum cryptography. “It’s not only harder to break, but it allows you to know if someone has been eavesdropping, or listening in on your transmission. Imagine someone wiretapping your phone, but now, every time that person tries to listen in on your conversation, the audio gets jumbled. With quantum cryptography, if someone tries to extract information, it changes the system, and both the transmitter and the receiver are aware of it.”

To conduct the research, Lucero and his colleagues designed and fabricated a quantum processor to map the problem of factoring the number 15 onto a purpose-built superconducting quantum circuit. “We chose the number 15 because it is the smallest composite number that satisfies the conditions appropriate to test Shor’s algorithm — it is a product of two prime numbers, and it’s not even,” he explained.

The quantum processor was implemented using a quantum circuit composed of four superconducting phase qubits — the quantum equivalents of transistors — and five microwave resonators. The complexity of operating these nine quantum elements required building a control system that allows for precise operation and a significant degree of automation — a prototype that will facilitate scaling up to larger and more complex circuits. The research represents a significant step toward a scalable quantum architecture while meeting a benchmark for quantum computation, as well as having historical relevance for quantum information and cryptography.

“After repeating the experiment 150,000 times, we showed that our quantum processor got the right answer just under half the time” Lucero said. “The best we can expect from Shor’s algorithm is to get the right answer exactly 50 percent of the time, so our results were essentially what we’d expect theoretically.”

The next step, according to Lucero, is to increase the quantum coherence times and go from nine quantum elements to hundreds, then thousands, and on to millions. “Now that we know 15=3×5, we can start thinking about how to factor larger — dare I say — more practical numbers,” he said.

Other UCSB researchers participating in the study include John Martinis, professor of physics; Rami Barends, Yu Chen, Matteo Mariantoni, and Y. Yin, postdoctoral fellows in physics; and physics graduate students Julian Kelly, Anthony Megrant, Peter O’Malley, Daniel Sank, Amit Vainsencher, Jim Wenner, and Ted White.

Story Source:

The above story is reprinted from materials provided by University of California – Santa Barbara.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

  1. Erik Lucero, R. Barends, Y. Chen, J. Kelly, M. Mariantoni, A. Megrant, P. O’Malley, D. Sank, A. Vainsencher, J. Wenner, T. White, Y. Yin, A. N. Cleland & John M. Martinis. Computing prime factors with a Josephson phase qubit quantum processor. Nature Physics, 19 August 2012 DOI: 10.1038/nphys2385

Need to cite this story in your essay, paper, or report? Use one of the following formats:



University of California – Santa Barbara (2012, August 19). Researchers make quantum processor capable of factoring a composite number into prime factors. ScienceDaily. Retrieved December 28, 2012, from­ /releases/2012/08/120819153743.htm

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