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Category: computing – Page 168

Aalto University researchers are the first in the world to measure qubits with ultrasensitive thermal detectors—thus evading the Heisenberg uncertainty principle.

Chasing ever-higher qubit counts in near-term quantum computers constantly demands new feats of engineering.

Among the troublesome hurdles of this scaling-up race is refining how qubits are measured. Devices called parametric amplifiers are traditionally used to do these measurements. But as the name suggests, the device amplifies weak signals picked up from the qubits to conduct the readout, which causes unwanted noise and can lead to decoherence of the qubits if not protected by additional large components. More importantly, the bulky size of the amplification chain becomes technically challenging to work around as qubit counts increase in size-limited refrigerators.

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A future quantum network of optical fibers will likely maintain communication between distant quantum computers. Sending quantum information rapidly across long distances has proved difficult, in part because most photons don’t survive the trip. Now Viktor Krutyanskiy of the University of Innsbruck, Austria, and his colleagues have more than doubled the success rate for sending photons that are quantum mechanically entangled with atoms to a distant site [1]. Instead of the previous approach of sending photons one at a time and waiting to see if each one arrives successfully, the researchers sent photons in groups of three. They believe that sending photons in larger numbers should be feasible in the future, allowing much faster transmission of quantum information.

Quantum networks require entanglement distribution, which involves sending a photon entangled with a local qubit to a distant location. The distribution system must check for the arrival and for the entanglement of each photon at the remote site before another attempt can be made, which can be time consuming. For a 100-km-long fiber, the light travel time combined with losses in the fiber and other inefficiencies limit the rate for this process to about one successful photon transfer per second using state-of-the-art equipment.

For faster distribution, Krutyanskiy and his colleagues trapped three calcium ions (qubits) in an optical cavity and performed repeated rounds of their protocol: in rapid sequence, each ion was triggered to emit an entangled photon that was sent down a 101-km-long, spooled optical fiber. In one experiment, the team performed nearly 900,000 of these “attempts,” detecting entangled photons at the far end 1906 times. The effective success rate came out to 2.9 per second. The team’s single-ion success rate was 1.2 per second.

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Researchers have discovered two techniques that could enable attackers to bypass audit logs or generate less severe entries when downloading files from SharePoint.

Microsoft SharePoint is a web-based collaborative platform that integrates with Microsoft Office and 365, primarily as a document management and data storage system.

Many companies use it for document management and collaboration, creating websites and corporate intranets, automating complex workflows, and enterprise content management applications.

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“For the first time we have physical evidence showing us what was happening in the moon’s interior during this critical stage in its evolution, and that’s really exciting,” said Dr. Jeff Andrews-Hanna.

Our Moon has long been hypothesized to have formed from a planet-sized object colliding with the Earth. But, what happened after and how can its unique geologic exterior and interior be explained? This is what a recent study published in Nature Geoscience hopes to address as an international team of researchers led by the Lunar and Planetary Laboratory (LPL) at the University of Arizona used a combination of spacecraft data and computer models to investigate the geologic processes that led to heavier elements being present on the nearside of the Moon, which is constantly facing Earth due to being tidally locked with our planet. This study holds the potential to help researchers better understand the geologic mechanisms behind planetary formation and could lead to gaining greater insight into how rocky planets like Earth and Mars formed.

For the study, the researchers used data from NASA’s GRAIL mission, which was used to map gravitational anomalies on the Moon, and computer models to determine the distribution of ilmenite, a combination of titanium and iron, across the Moon’s nearside and how much sunk into the Moon’s interior during the Moon’s formation and evolution. It has been previously hypothesized that while ilmenite sunk to the Moon’s interior early on, portions of it returned to the surface from volcanism, and the mechanisms behind these events have led scientists puzzled.

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