PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

NIST demonstrates how losing information can benefit quantum computing

2013-11-25
(Press-News.org) Contact information: Laura Ost
laura.ost@nist.gov
National Institute of Standards and Technology (NIST)
NIST demonstrates how losing information can benefit quantum computing

BOULDER, Colo -- Suggesting that quantum computers might benefit from losing some data, physicists at the National Institute of Standards and Technology (NIST) have entangled—linked the quantum properties of—two ions by leaking judiciously chosen information to the environment.

Researchers usually strive to perfectly shield ions (charged atoms) in quantum computing experiments from the outside world. Any "noise" or interference, including heat generated by the experiment and measurements that cause fragile quantum states to collapse, can ruin data and prevent reliable logic operations, the conventional approach to quantum information processing.

Turning bug into feature, a collaboration of physicists from NIST and the University of Copenhagen in Denmark decided to think and work outside the box. They cleverly linked the experiment to the outside world to establish and maintain the entanglement of two ions. Entanglement is a curious feature of the quantum world that will be necessary to process and transport quantum data or correct errors in future quantum computers.

The new research is described in a Nature paper posted online Nov. 24,* along with similar work at Yale University using superconducting circuits.

"These new methods might be used to create entangled states that would be a resource in a traditional, logic-based quantum computer," NIST postdoctoral researcher John Gaebler says. "But there are also alternative architectures in which, for example, one couples a quantum computer to a specific noise environment and the resulting state of the computer contains the solution to the target problem."

The NIST experiments used two beryllium ions as quantum bits (qubits) to store quantum information and two partner magnesium ions, which were cooled with three ultraviolet laser beams to release heat.

The qubits were entangled by two ultraviolet laser beams and induced to "leak" any unwanted quantum states to the environment through continuous application of microwaves and one laser beam. The unwanted data were coupled to the outgoing heat in such a way that the qubits were left in only the desired entangled state—which happens to be the point of lowest motional energy, where no further heat and information is released to the environment.

Unlike a logic operation, the process can be started from any state of the ions and still yield the same final state. The scheme also can tolerate some kinds of noise that might cause a traditional logic gate to fail. For instance, the lasers and microwaves had no negative effects on the target entangled state but reshuffled any unwanted states.

All operations applied at the same time quickly drove the two qubits into a specific entangled state and kept them in that state most of the time. The qubits approached the target state within a few milliseconds and were found to be in the correct entangled state 75 percent of the time. The qubit state deteriorated slightly over longer times as the qubits were disturbed by errant laser emissions. By applying about 30 repetitions of the four steps in a particular order, scientists boosted the success rate to 89 percent in a separate experiment.



INFORMATION:

Co-authors of the paper include two collaborators at QUANTOP, The Niels Bohr Institute, University of Copenhagen. The work was supported in part by the Intelligence Advanced Research Projects Activity, Office of Naval Research, and the European Union's Seventh Framework Program.

* Y. Lin, J.P. Gaebler, F. Reiter, T.R. Tan, R. Bowler, A.S. Sorensen, D. Leibfried and D.J. Wineland. Dissipative production of a maximally entangled steady state. Nature. Posted online Nov. 24, 2013.

Sidebar: How Lost Data Generates Entanglement

The NIST process for using lost data to generate entanglement works like this: Two ultraviolet laser beams entangle the two ion qubits' internal "spins," analogous to tiny bar magnets pointing up or down. The lasers are carefully tuned to couple the ions' synchronized, back-and-forth sideways motion to their spins, entangling this motion with the spins.

The spins have three possible correlations: Both qubits spin up, both spin down, or one is up and one is down. The desired entangled state is a superposition of spins up-down and down-up at the same time. Superposition is another special feature of the quantum world. A measurement of this state with another special-purpose laser beam causes quantum states to collapse, resulting in spins up-down, or the opposite, spins down-up. Such measurements are made by detecting light signals; spin up scatters laser light, whereas spin down does not.

If the two spins are in the desired entangled state and the lowest motional energy state, they are unaffected by all laser and microwave fields. But microwaves and one ultraviolet laser beam reshuffle all other spin states and at the same time boost the qubits to an intermediate state with higher motional energy. This energy is then removed from the qubits by three cooling laser beams applied to the magnesium ions. This continuous feedback loop alters the qubits spins until they settle into the entangled state that is no longer affected by the driving fields.



ELSE PRESS RELEASES FROM THIS DATE:

How living cells solved a needle in a haystack problem to produce electrical signals

2013-11-25
How living cells solved a needle in a haystack problem to produce electrical signals Filtered from a vast sodium sea, more than 1 million calcium ions per second gush through our cells' pores to generate charges Scientists have figured out how calcium channels – the infinitesimal ...

New genomic study provides a glimpse of how whales could adapt to ocean

2013-11-25
New genomic study provides a glimpse of how whales could adapt to ocean The latest study was published online in Nature Genetics November 24, 2013, Shenzhen, China - In a paper published in Nature Genetics, researchers from Korea Institute of Ocean Science and Technology, Korea Genome Research ...

Scientists prove X-ray laser can solve protein structures from scratch

2013-11-25
Scientists prove X-ray laser can solve protein structures from scratch SLAC's linac coherent light source reaches key milestone in decoding biological structures that were out of reach A study shows for the first time that X-ray lasers can ...

X-rays reveal another feature of high-temperature superconductivity

2013-11-25
X-rays reveal another feature of high-temperature superconductivity Discovery of a giant resonance puts these materials further apart Classical and high-temperature superconductors differ hugely in the value of the critical temperatures at which ...

UNL scientists develop novel X-ray device

2013-11-25
UNL scientists develop novel X-ray device Research quality X-rays could have widespread applications Lincoln, Neb., Nov. 24 – Using a compact but powerful laser, a research team at the University of Nebraska-Lincoln has developed a new way to generate ...

Unusual greenhouse gases may have raised ancient Martian temperature

2013-11-25
Unusual greenhouse gases may have raised ancient Martian temperature Much like the Grand Canyon, Nanedi Valles snakes across the Martian surface suggesting that liquid water once crossed the landscape, according to a team of researchers who believe that molecular hydrogen ...

Study identifies protein essential for immune recognition, response to viral infection

2013-11-25
Study identifies protein essential for immune recognition, response to viral infection Mice lacking GEF-H1 protein expression unable to mount immune defense against influenza A Massachusetts General Hospital (MGH)-led research team has identified an immune ...

Even if emissions stop, carbon dioxide could warm Earth for centuries

2013-11-25
Even if emissions stop, carbon dioxide could warm Earth for centuries Even if carbon dioxide emissions came to a sudden halt, the carbon dioxide already in Earth's atmosphere could continue to warm our planet for hundreds of years, according to Princeton University-led ...

Scientists find brain region that helps you make up your mind

2013-11-25
Scientists find brain region that helps you make up your mind One of the smallest parts of the brain is getting a second look after new research suggests it plays a crucial role in decision making. A University of British Columbia study published today ...

Meat, egg and dairy nutrient essential for brain development

2013-11-25
Meat, egg and dairy nutrient essential for brain development Deficiency of asparagine synthetase caused by rare genetic disorder affects brain development This news release is available in French. Asparagine, found in foods such as meat, ...

LAST 30 PRESS RELEASES:

Study tracks chromium chemistry in irradiated molten salts

Scientists: the beautiful game is a silver bullet for global health

Being physically active, even just a couple of days a week, may be key to better health

High-fat diet promote breast cancer metastasis in animal models

A router for photons

Nurses and AI collaborate to save lives, reduce hospital stays

Multi-resistance in bacteria predicted by AI model

Tinker Tots: A citizen science project to explore ethical dilemmas in embryo selection

Sensing sickness

Cost to build multifamily housing in California more than twice as high as in Texas

Program takes aim at drinking, unsafe sex, and sexual assault on college campuses

Inability to pay for healthcare reaches record high in U.S.

Science ‘storytelling’ urgently needed amid climate and biodiversity crisis

KAIST Develops Retinal Therapy to Restore Lost Vision​

Adipocyte-hepatocyte signaling mechanism uncovered in endoplasmic reticulum stress response

Mammals were adapting from life in the trees to living on the ground before dinosaur-killing asteroid

Low LDL cholesterol levels linked to reduced risk of dementia

Thickening of the eye’s retina associated with greater risk and severity of postoperative delirium in older patients

Almost one in ten people surveyed report having been harmed by the NHS in the last three years

Enhancing light control with complex frequency excitations

New research finds novel drug target for acute myeloid leukemia, bringing hope for cancer patients

New insight into factors associated with a common disease among dogs and humans

Illuminating single atoms for sustainable propylene production

New study finds Rocky Mountain snow contamination

Study examines lactation in critically ill patients

UVA Engineering Dean Jennifer West earns AIMBE’s 2025 Pierre Galletti Award

Doubling down on metasurfaces

New Cedars-Sinai study shows how specialized diet can improve gut disorders

Making moves and hitting the breaks: Owl journeys surprise researchers in western Montana

PKU Scientists simulate the origin and evolution of the North Atlantic Oscillation

[Press-News.org] NIST demonstrates how losing information can benefit quantum computing