David Kirkpatrick

February 27, 2010

Getting closer to a quantum computer

Another incremental step toward functional quantum computing. We don’t need quantum computing just yet, but we will.

The release:

UW-Madison physicists build basic quantum computing circuit

MADISON — Exerting delicate control over a pair of atoms within a mere seven-millionths-of-a-second window of opportunity, physicists at the University of Wisconsin-Madison created an atomic circuit that may help quantum computing become a reality.

Quantum computing represents a new paradigm in information processing that may complement classical computers. Much of the dizzying rate of increase in traditional computing power has come as transistors shrink and pack more tightly onto chips — a trend that cannot continue indefinitely.

“At some point in time you get to the limit where a single transistor that makes up an electronic circuit is one atom, and then you can no longer predict how the transistor will work with classical methods,” explains UW-Madison physics professor Mark Saffman. “You have to use the physics that describes atoms — quantum mechanics.”

At that point, he says, “you open up completely new possibilities for processing information. There are certain calculational problems… that can be solved exponentially faster on a quantum computer than on any foreseeable classical computer.”

With fellow physics professor Thad Walker, Saffman successfully used neutral atoms to create what is known as a controlled-NOT (CNOT) gate, a basic type of circuit that will be an essential element of any quantum computer. As described in the Jan. 8 issue of the journal Physical Review Letters, the work is the first demonstration of a quantum gate between two uncharged atoms.

The use of neutral atoms rather than charged ions or other materials distinguishes the achievement from previous work. “The current gold standard in experimental quantum computing has been set by trapped ions… People can run small programs now with up to eight ions in traps,” says Saffman.

However, to be useful for computing applications, systems must contain enough quantum bits, or qubits, to be capable of running long programs and handling more complex calculations. An ion-based system presents challenges for scaling up because ions are highly interactive with each other and their environment, making them difficult to control.

“Neutral atoms have the advantage that in their ground state they don’t talk to each other, so you can put more of them in a small region without having them interact with each other and cause problems,” Saffman says. “This is a step forward toward creating larger systems.”

The team used a combination of lasers, extreme cold (a fraction of a degree above absolute zero), and a powerful vacuum to immobilize two rubidium atoms within “optical traps.” They used another laser to excite the atoms to a high-energy state to create the CNOT quantum gate between the two atoms, also achieving a property called entanglement in which the states of the two atoms are linked such that measuring one provides information about the other.

Writing in the same journal issue, another team also entangled neutral atoms but without the CNOT gate. Creating the gate is advantageous because it allows more control over the states of the atoms, Saffman says, as well as demonstrating a fundamental aspect of an eventual quantum computer.

The Wisconsin group is now working toward arrays of up to 50 atoms to test the feasibility of scaling up their methods. They are also looking for ways to link qubits stored in atoms with qubits stored in light with an eye toward future communication applications, such as “quantum internets.”

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This work was funded by grants from the National Science Foundation, the Army Research Office and the Intelligence Advanced Research Projects Agency.

July 18, 2008

Bossing electrons around

Filed under: Science — Tags: , , , , , — David Kirkpatrick @ 2:34 pm

From KurzweilAI.net:

Quantum Leap
Technology Review, July 17, 2008

An international team of researchers has shown that it can control the quantum state of a single electron in a silicon transistor–even putting the electron in two places at once. Their discovery could help pave the way toward a practical quantum computer.

The electronc could be in one of three states. At low electric fields, the electron remained bound to an arsenic atom. At high electric fields, the electron was pulled away from the atom. But when the electric field was at just the right level, the electron would be in both places at once.

 
Read Original Article>>

April 25, 2008

Supercomputing and nanotech products in the news

Today’s KurzweilAI.net news includes a quantum computer breakthrough and news on the ubiquity of nanotech products:

Riding D-Wave
Technology Review, May/June 2008

In November of last year, with $60 million in funding, D-Wave demonstrated what it claimed was a 28-qubit adiabatic quantum computer, based on a design by MIT quantum computing scientist Seth Lloyd.

Now, the company’s scientists are attempting to demonstrate the fundamentally quantum-mechanical nature of their device.

 
Read Original Article>>

New nanotech products hitting the market at the rate of 3 to 4 per week
PhysOrg.com, April 24, 2008

New nanotechnology consumer products are coming on the market at the rate of 3 to 4 per week, Project on Emerging Nanotechnologies (PEN) Project Director David Rejeski said in testimony before the Senate Commerce Committee Thursday.

The number of consumer products using nanotechnology has grown from 212 to 609 since PEN launched the world’s first online inventory of manufacturer-identified nanotech goods in March 2006. Health and fitness items, which includes cosmetics and sunscreens, represent 60 percent of inventory products. The list of products is available free at www.nanotechproject.org/consumerproducts.
 
Read Original Article>>

April 16, 2008

Molecular movie stars, stem cells and quantum computing

Nice roundup from KurzweilAI.net today.

First up is nngews on a more accurate method for creating movies of molecular and biological processes

Keeping with the biology theme is a breakthrough for treating heart damage with stem cells.

Finishing the group is a bit about progress toward a quantum computer.

Movies of biological and chemical molecules made for first time
KurzweilAI.net, April 16, 2008Argonne National Laboratory scientists have developed accurate techniques for making movies of actual biological and chemical molecules for the first time.


X-ray movie reveals movement of DNA molecule

Biological and organic molecules in solution are far more complex than the standard crystalline structures of salt or metals since they are constantly moving and changing over time.

Using the high-intensity X-rays at the Advanced Photon Source, the scientists have measured images that are blurred by these motions and used computer processing algorithms to create more accurate movies of the molecular motions.

Source: Argonne scientists develop techniques for creating molecular movies

 

Molecule prompts blood stem cells to help repair heart damage in animal model
PhysOrg.com, April 15, 2008University of Texas Southwestern Medical Center researchers used drug-treated blood stem cells to repair heart damage in an animal model.

They screened about 147,000 molecules to find one that could transform human blood stem cells into a form resembling immature heart cells. When they implanted blood stem cells activated by this compound into injured rodent hearts, the human cells took root and improved the animals’ heart function.

 
Read Original Article>>

 

Toward a Quantum Internet
Technology Review, April 15, 2008Northwestern University researchers have build a quantum logic gate–a fundamental component of a quantum computer–within an optical fiber, using entangled photon pairs.

The gate could be part of a circuit that relays information securely, over hundreds of kilometers of fiber, from one quantum computer to another. It could also be used on its own to find solutions to complicated mathematical problems.

 
Read Original Article>>

March 28, 2008

Nano, solar and other KurzweilAI.net news

Different format today for the KurzweilAI.net newsletter highlights. There is so much good stuff I’m dropping bits directly from the newsletter. Today features solar, stretchy silicon, quantum computing news, self assembly, electricity producing nanotubes, and a possible successor to silicon — graphene.

Do follow the links.

From the newsletter:

*************************
More-Powerful Solar Cells
Technology Review Mar. 27, 2008
*************************
An MIT researcher has found a way
to improve the efficiency of
multicrystalline silicon solar cells
by 27 percent without raising costs,
making them as efficient as the more
expensive single-crystal cells. The
first cells incorporating the new
technology are predicted to cost
$1.65 per watt, compared to $2.10
per watt today….
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8278&m=39667

*************************
Stretchy circuits promise elastic
gadgets
NewScientist.com news service Mar. 27, 2008
*************************
University of Illinois at
Urbana-Champaign researchers have
made stretchable and flexible
silicon and plastic integrated
circuits that are just one
crystal–1.5 microns–thick. The
circuits are designed so that the
plastic, not the silicon, absorbs
most of the stress when the chips
are bent. Until now, integrated
circuits have been limited by…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8277&m=39667

*************************
Silicon chips for optical quantum
technologies
KurzweilAI.net Mar. 28, 2008
*************************
Bristol University researchers have
demonstrated the world’s smallest
optical controlled NOT gate–the
building block of a quantum
computer–fabricated from silica
wave-guides on a silicon chip. The
team generated pairs of photons,
each encoding a quantum bit or qubit
of information. They coupled these
photons into and out of the…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8276&m=39667

*************************
Nanomaterial turns radiation
directly into electricity
NewScientist.com news service Mar. 27, 2008
*************************
Two researchers–a former Los
Alamos National Laboratory engineer
and an Alabama A&M University
researcher–have developed highly
efficient nanotube-based tile
materials that can convert
radiation, not heat, from nuclear
materials into electricity. The
tiles are made of carbon nanotubes
packed with gold and surrounded by
lithium hydride….
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8275&m=39667

*************************
Self-Assembled Materials Form Mini
Stem Cell Lab
KurzweilAI.net Mar. 28, 2008
*************************
Northwestern University researchers
have built self-assembling thin-film
sacs able to hold human stem cells
for four weeks in culture, keeping
the cells separated while allowing
proteins to cross the membrane. This
new mode of self-assembly from a mix
of peptide amphiphiles and
biopolymers also can produce thin
films whose size and shape can be…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8273&m=39667

*************************
Is Graphene the New Silicon?
KurzweilAI.net Mar. 28, 2008
*************************
University of Maryland physicists
have found that graphene conducts
electricity at room temperature with
less intrinsic resistance than any
other known material. Graphene, a
new material that combines aspects
of semiconductors and metals, is one
of the materials being considered as
a potential replacement for silicon
for future computing. The…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8271&m=39667