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Category: particle physics – Page 396

But Aspelmeyer and his colleagues could not declare victory quite yet: they still had to rule out the possibility that the source mass modulation was generating other forces on the test mass that would oscillate at precisely the same frequency. Periodic rocking of the table supporting the experimental apparatus, caused by recoil from the barely visible motion of the source mass, was just one of a host of confounders the researchers had to carefully quantify. In the end, they found that all known nongravitational forces would be at least 10 times smaller than the gravitational interaction.

Reaching toward Quantum Scales

Aspelmeyer believes that an improved torsion pendulum will be sensitive to gravity from masses 5000 times smaller still—lighter than a single eyelash. His ultimate goal is to experimentally test the quantum nature of gravity, a question that has perplexed physicists for nearly a century. Quantum mechanics is one of the most successful and precisely tested theories in all of science: it describes everything from the behavior of subatomic particles to the semiconductor physics that makes modern computing possible. But attempts to develop a quantum theory of gravity have repeatedly been stymied by contradictory and nonsensical predictions.

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Hence, while the fast particles are abundant in molecular systems, they are practically lacking in active matter. These fast particle can overcome the attraction forces of the molecular surrounding and give rise to the gaseous phase; the lack of fast particles in active matter results in the lack of the gas, coexisting with the liquid phase. If the particle density is still larger and the repulsive forces are strong, the active matter falls into a solid phase, Fig. 1 d, where the particles mobility is suppressed.

In some range of parameters a novel swirlonic phase is formed, Fig. 1e. It is comprised of swirlons —“super-particles” with many astonishing properties which we address below. Individual active particles in swirlons perform a swirling motion around their common center. As we demonstrate in what follows, the swirlons are formed when local fluctuating force exceeds the critical force, which characterizes the ability of an active particle to move against an applied load.

Finally, for large density and very strong attractive forces a collapsed state is observed, Fig. 1 f. In the collapsed state active particle also move around the common center, however the character of the motion is rather irregular. In the present study we will focus on the gaseous, liquid and especially on the swirlonic phase.

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This month is a time to celebrate. CERN has just announced the discovery of four brand new particles at the Large Hadron Collider (LHC) in Geneva.

This means that the LHC has now found a total of 59 new particles, in addition to the Nobel prize-winning Higgs boson, since it started colliding protons – particles that make up the atomic nucleus along with neutrons – in 2009.

Excitingly, while some of these new particles were expected based on our established theories, some were altogether more surprising.

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Canadian startup Xanadu says their quantum computer is cloud-accessible, Python programmable, and ready to scale.

Quantum computers based on photons may have some advantages over electron-based machines, including operating at room temperature and not temperatures colder than that of deep space. Now, say scientists at quantum computing startup Xanadu, add one more advantage to the photon side of the ledger. Their photonic quantum computer, they say, could scale up to rival or even beat the fastest classical supercomputers—at least at some tasks.

Whereas conventional computers switch transistors either on or off to symbolize data as ones and zeroes, quantum computers use quantum bits or “qubits” that, because of the bizarre nature of quantum physics, can exist in a state known as superposition where they can act as both 1 and 0. This essentially lets each qubit perform multiple calculations at once.

The more qubits are quantum-mechanically connected entangled together, the more calculations they can simultaneously perform. A quantum computer with enough qubits could in theory achieve a “quantum advantage” enabling it to grapple with problems no classical computer could ever solve. For instance, a quantum computer with 300 mutually-entangled qubits could theoretically perform more calculations in an instant than there are atoms in the visible universe.

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On 21 May 2019, from a distance of 7 billion light-years away, our gravitational wave detectors were rocked by the most massive collision yet. From analysis of the signal, astronomers concluded that the detection was the result of two black holes smashing together, weighing in at 66 and 85 times the mass of the Sun respectively.

But what if it was something else? A new study offers a different interpretation of the event. It’s possible, according to an international team of astrophysicists, that the two objects were not black holes at all, but mysterious, theoretical objects called boson stars — potentially made up of elusive candidates for dark matter.

The gravitational wave event, called GW 190521, was a spectacular discovery. The object that resulted from the merger of the two objects would have been a black hole at around 142 times the mass of the Sun — within the intermediate mass range that no black hole had ever been detected before, called the black hole upper mass gap.

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Planned future experiments will help researchers choose between the two pictures. But whichever model is right, SeaQuest’s hard data about the proton’s inner antimatter will be immediately useful, especially for physicists who smash protons together at nearly light speed in Europe’s Large Hadron Collider. When they know exactly what’s in the colliding objects, they can better piece through the collision debris looking for evidence of new particles or effects. Juan Rojo of VU University Amsterdam, who helps analyze LHC data, said the SeaQuest measurement “could have a big impact” on the search for new physics, which is currently “limited by our knowledge of the proton structure, in particular of its antimatter content.”

Twenty years ago, physicists began investigating a mysterious asymmetry inside the proton. Their results show how antimatter helps stabilize every atom’s core.

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Oak Ridge National Laboratory scientists demonstrated that an electron microscope can be used to selectively remove carbon atoms from graphene ’s atomically thin lattice and stitch transition-metal dopant atoms in their place.

This method could open the door to making quantum building blocks that can interact to produce exotic electronic, magnetic and topological properties.

This is the first precision positioning of transition-metal dopants in graphene. The produced graphene-dopant complexes can exhibit atomic-like behavior, inducing desired properties in the graphene.

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Scientists get dramatically better resolution at X-ray free-electron lasers with a new technique.

Intense, ultrashort X-ray pulses from hard X-ray free-electron lasers (XFELs) can capture images of biological structures down to the atomic scale and shed light on the fastest processes in nature with a shutter speed of just one femtosecond, a millionth of a billionth of a second.

However, on these miniscule time scales, it is extremely difficult to synchronize the X-ray pulse that sparks a reaction in the sample with the follow-up pulse that observes the reaction. This problem, called timing jitter, is a major hurdle in performing these XFEL experiments with ever-better resolution.

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