Embrace Foundation - Astrophysics, Quantum Physics & The Nature of Reality

Researchers have recreated the universe's primordial soup in miniature format by colliding lead atoms with

extremely high energy in the 27 km long particle accelerator, the LHC at CERN in Geneva. The primordial soup

is a so-called quark-gluon plasma and researchers from the Niels Bohr Institute, among others, have measured

its liquid properties with great accuracy at the LHC's top energy. The results have been submitted to Physical

Review Letters.

A few billionths of a second after the Big Bang, the universe was made up of a kind of extremely hot and dense primordial

soup of the most fundamental particles, especially quarks and gluons. This state is called quark-gluon plasma. By colliding

lead nuclei at a record-high energy of 5.02 TeV in the world's most powerful particle accelerator, the 27 km long Large

Hadron Collider, LHC at CERN in Geneva, it has been possible to recreate this state in the ALICE experiment's detector

and measure its properties.

"The analyses of the collisions make it possible, for the first time, to measure the precise characteristics of a quark-gluon

plasma at the highest energy ever and to determine how it flows," explains You Zhou, who is a postdoc in the ALICE

research group at the Niels Bohr Institute. You Zhou, together with a small, fast-working team of international collaboration

partners, led the analysis of the new data and measured how the quark-gluon plasma flows and fluctuates after it is formed

by the collisions between lead ions.

Advanced methods of measurement

The focus has been on the quark-gluon plasma's collective properties, which show that this state of matter behaves more

like a liquid than a gas, even at the very highest energy densities. The new measurements, which uses new methods to

study the correlation between many particles, make it possible to determine the viscosity of this exotic fluid with great

precision.

You Zhou explains that the experimental method is very advanced and is based on the fact that when two spherical atomic

nuclei are shot at each other and hit each other a bit off center, a quark-gluon plasma is formed with a slightly elongated

shape somewhat like an American football. This means that the pressure difference between the centre of this extremely

hot 'droplet' and the surface varies along the different axes. The pressure differential drives the expansion and flow and

consequently one can measure a characteristic variation in the number of particles produced in the collisions as a function

of the angle.

Mapping the primordial soup

"It is remarkable that we are able to carry out such detailed measurements on a drop of 'early universe', that only has a

radius of about one millionth of a billionth of a meter. The results are fully consistent with the physical laws of

hydrodynamics, i.e. the theory of flowing liquids and it shows that the quark-gluon plasma behaves like a fluid. It is however

a very special liquid, as it does not consist of molecules like water, but of the fundamental particles quarks and gluons,"

explains Jens Jørgen Gaardhøje, professor and head of the ALICE group at the Niels Bohr Institute at the University of

Copenhagen.

Jens Jørgen Gaardhøje adds that they are now in the process of mapping this state with ever increasing precision -- and

even further back in time.

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The above post is reprinted from materials provided by University of Copenhagen - Niels Bohr Institute. Note: Materials

may be edited for content and length.

www.sciencedaily.com/releases/2016/02/160209121543.htm

Atoms placed precisely in silicon can act as quantum simulator

SCIENCE DAILY

Date: April 22nd. 2016

Source: University of New South Wales

"Previously this kind of exact quantum simulation could not be performed without interference from the environment, which

typically destroys the quantum state," says senior author Professor Sven Rogge, Head of the UNSW School of Physics

and program manager with the ARC Centre of Excellence for Quantum Computation and Communication Technology

(CQC2T).

"Our success provides a route to developing new ways to test fundamental aspects of quantum physics and to design

new, exotic materials -- problems that would be impossible to solve even using today's fastest supercomputers."

The study is published in the journal Nature Communications. The lead author was UNSW's Dr Joe Salfi and the team

included CQC2T director Professor Michelle Simmons, other CQC2T researchers from UNSW and the University of

Melbourne, as well as researchers from Purdue University in the US.

Two dopant atoms of boron only a few nanometres from each other in a silicon crystal were studied. They behaved like

valence bonds, the "glue" that holds matter together when atoms with unpaired electrons in their outer orbitals overlap and

bond.

The team's major advance was in being able to directly measure the electron "clouds" around the atoms and the energy of

the interactions of the spin, or tiny magnetic orientation, of these electrons.

They were also able to correlate the interference patterns from the electrons, due to their wave-like nature, with their

entanglement, or mutual dependence on each other for their properties.

"The behaviour of the electrons in the silicon chip matched the behaviour of electrons described in one of the most

important theoretical models of materials that scientists rely on, called the Hubbard model," says Dr Salfi.

"This model describes the unusual interactions of electrons due to their wave-like properties and spins. And on of its main

applications is to understand how electrons in a grid flow without resistance, even though they repel each other," he says.

The team also made a counterintuitive find -- that the entanglement of the electrons in the silicon chip increased the further

they were apart.

"This demonstrates a weird behaviour that is typical of quantum systems," says Professor Rogge.

"Our normal expectation is that increasing the distance between two objects will make them less, not more, dependent on

each other.

"By making a larger set of dopant atoms in a grid in a silicon chip we could realise a vision first proposed in the 1980s by

the physicist Richard Feynman of a quantum system that can simulate nature and help us understand it better," he says.

The publication of this latest advance towards the development of a silicon-based quantum computer at UNSW coincided

with the opening of the university's new quantum computing laboratories by Australian Prime Minister Malcolm Turnbull.

Story Source:

The above post is reprinted from materials provided by University of New South Wales. Note: Materials may be edited for content and

length.

https://www.sciencedaily.com/releases/2016/04/160422115317.htm

The atom without properties

SCIENCE DAILY

Date: April 21st. 2016

Source: University of Basel

Everyday objects possess properties independently of each other and regardless of whether we observe them or not.

Einstein famously asked whether the moon still exists if no one is there to look at it; we answer with a resounding yes. This

apparent certainty does not exist in the realm of small particles. The location, speed or magnetic moment of an atom can

be entirely indeterminate and yet still depend greatly on the measurements of other distant atoms.

Experimental test of Bell correlations

With the (false) assumption that atoms possess their properties independently of measurements and independently of

each other, a so-called Bell inequality can be derived. If it is violated by the results of an experiment, it follows that the

properties of the atoms must be interdependent. This is described as Bell correlations between atoms, which also imply

that each atom takes on its properties only at the moment of the measurement. Before the measurement, these properties

are not only unknown -- they do not even exist.

A team of researchers led by professors Nicolas Sangouard and Philipp Treutlein from the University of Basel, along with

colleagues from Singapore, have now observed these Bell correlations for the first time in a relatively large system,

specifically among 480 atoms in a Bose-Einstein condensate. Earlier experiments showed Bell correlations with a

maximum of four light particles or 14 atoms. The results mean that these peculiar quantum effects may also play a role in

larger systems.

Large number of interacting particles

In order to observe Bell correlations in systems consisting of many particles, the researchers first had to develop a new

method that does not require measuring each particle individually -- which would require a level of control beyond what is

currently possible. The team succeeded in this task with the help of a Bell inequality that was only recently discovered. The

Basel researchers tested their method in the lab with small clouds of ultracold atoms cooled with laser light down to a few

billionths of a degree above absolute zero. The atoms in the cloud constantly collide, causing their magnetic moments to

become slowly entangled. When this entanglement reaches a certain magnitude, Bell correlations can be detected. Author

Roman Schmied explains: "One would expect that random collisions simply cause disorder. Instead, the quantum-

mechanical properties become entangled so strongly that they violate classical statistics."

More specifically, each atom is first brought into a quantum superposition of two states. After the atoms have become

entangled through collisions, researchers count how many of the atoms are actually in each of the two states. This division

varies randomly between trials. If these variations fall below a certain threshold, it appears as if the atoms have 'agreed' on

their measurement results; this agreement describes precisely the Bell correlations.

New scientific territory

The work presented, which was funded by the National Centre of Competence in Research Quantum Science and

Technology (NCCR QSIT), may open up new possibilities in quantum technology; for example, for generating random

numbers or for quantum-secure data transmission. New prospects in basic research open up as well: "Bell correlations in

many-particle systems are a largely unexplored field with many open questions -- we are entering uncharted territory with

our experiments," says Philipp Treutlein.

Story Source:

The above post is reprinted from materials provided by University of Basel. Note: Materials may be edited for content and length.

https://www.sciencedaily.com/releases/2016/04/160421141510.htm